Atomic Spectroscopy for Forensic Applications 1

ATOMIC SPECTROSCOPY FOR FORENSIC APPLICATIONS 1

(LA/ICPMS), modern atomic spectroscopy has proven Atomic Spectroscopy for itself to be a compelling and evolving tool in the Forensic Applications investigation of forensic evidence.

Diana M. Grant and Charles A. Peters FBI Laboratory, Washington, USA 1 INTRODUCTION

Forensic science may be defined as the application of scientific methods to problems that are addressed 1 Introduction 1 in a courtroom setting. Given that the results of an 2 Development of Atomic Spectroscopy 2 examination have the potential to affect a verdict at trial, 3 Applications 3 the law provides that physical evidence may be examined 3.1 Natural Products 4 by both prosecution and defense experts. The size of a 3.2 Drugs of Abuse 5 forensic specimen can thus present a sampling challenge 3.3 Suspected Poisonings 6 for analysts, particularly when a requested examination is 3.4 Lead Applications 8 destructive. Preservation of collected evidence is always 3.5 Gunshot Residue Analysis 10 a consideration prior to examination. The analyst must 4 Metals Analysis 11 ask the question: ‘‘Has the evidence been altered since or 4.1 General Applications 11 as a result of its collection?’’ Another issue that arises is 4.2 Precious Metals 12 the order in which examinations are performed so as not to preclude subsequent analyses. 5Glass 13 Evidentiary samples are generally analyzed for rela- 6 Laser Ablation 15 tional value to a suspect, victim, or crime scene. Specimens Acknowledgments 17 may readily associate a subject with a crime scene or .1,2/ Abbreviations and Acronyms 17 victim, as with DNA or fingerprints. More often, however, evidence from a victim or crime scene may be used Related Articles 17 as a circumstantial link to known materials found on a References 18 suspect or in his environment. For this type of specimen, the associative link will be comparative. That is, the relationship between a known Forensic science is a discipline that evolved from the and the questioned evidence will be assessed as to the interaction between law enforcement and the scientific degree of similarity. Whether the association is formed on community. The typical operating budget of laboratory the basis of color, texture, diameter, physical impressions, facilities created to support law enforcement is often far or compositional similarities at the elemental level, the below what is necessary for practical modernization. forensic examiner’s written opinion will assess the degree Hence, routine analyses that require low maintenance of comparability between the submitted known and .2/ and can be readily performed with practical experience questioned specimens. were quickly instituted as standard procedures in many Forensic scientists are often asked to determine which such laboratories. As an example, atomic absorption examinations are best suited to the collected evidence (AA) spectroscopy has served the forensic community for in a given case. Dialog between the scientist and the over 40 years and continues to work effectively for such evidence contributor is then necessary to establish what diverse applications as gunshot powder residue analysis questions are being asked and if answers are reasonably and toxicological examinations in suspected heavy metal achievable given the limitations of sample size and the poisoning cases. laboratory’s analytical capabilities. After all known or These and other traditional forensic applications have available analytical tools are employed to address the also utilized other forms of spectrochemical analysis such question(s) posed to the laboratory, a solid scientific as neutron activation. The advantage of the various forms foundation should be established upon which a legal of atomic spectroscopy over these other methods lies in opinion may be rendered. An ideal scenario would allow the practical considerations of accessibility and cost as that any necessary instrumentation would be readily much as in sampling requirements and detection limits. accessible, specimen size would be plentiful, and the From well established AA methods to the increasing condition of the evidence would be pristine. number of forensic applications being developed for laser External contamination and minimal sample size are ablation/inductively coupled plasma mass spectrometry just two examples of the problems often encountered

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 2 FORENSIC SCIENCE with forensic evidence. As with any object in limited 2 DEVELOPMENT OF ATOMIC supply, preservation of materials deemed to be evidential SPECTROSCOPY in nature is often a fundamental consideration in requests for analysis. Thus, an arguably nondestructive method The notion of coupling a plasma excitation source with a such as instrumental neutron activation analysis (INAA) multielement detection system in the mid-1960s ushered is quite useful for a wide range of applications in forensic in a new generation of workhorse instrumentation for the science assays..3–7/ However, INAA has not been readily modern analytical laboratory. Since then, industrial, envi- available for use by most forensic laboratories. The lack ronmental, and academic laboratories have demonstrated of convenient accessibility, required licensing for use of a wide applicability of plasma techniques to trace element such facilities, and regulatory waste disposal issues has studies..25–32/ Forensic laboratories have also published led to sustained interest in alternative methods of analysis studies of atomic spectrometry applications..33–36/ How- such as atomic spectroscopy. ever, as a discipline, forensic science seeks to apply AA spectroscopy has been well documented in forensic analytical techniques to evidence in a criminal mat- examinations involving suspected heavy metal poison- ter for the purpose of weighing the probative value of ing determinations in tissue samples, other biological that evidence. Therefore, only those techniques that materials, and for gunshot residue (GSR) analyses..8–19/ have been tested and validated by the scientific com- While INAA has the advantage of multielement capa- munity are suitable for presentation in a courtroom. bility for solid samples, which preserves the condition Such methods are thus no longer considered research of a specimen, AA is more readily accessible, and ulti- endeavors as much as they are new applications of estab- mately cheaper to use and maintain. The merits of both lished protocols, already discussed extensively in relevant methods were compared in early forensic application journals. papers..20,21/ Moreover, while all of the conventional atomic spec- Atomic spectroscopy most routinely involves dissolu- trometry techniques mentioned thus far have become tion of a solid matrix before analysis. Traditional AA well established in a variety of analytical problem solv- utilizes a flame or furnace system to atomize aque- ing arenas, AA spectroscopy is still the most popular ous samples. Later systems that allow for solid sample of these methods for routine forensic examinations..37/ atomization have improved sensitivity for a variety of Examples range from GSR analysis to toxicological assays matrices..22/ Most recently, plasma technology has grown for the presence of heavy metal poisoning in hair..38,39/ in popularity due to its efficiency in ionizing an aque- Therefore, a discussion of atomic spectroscopy techniques ous sample..23/ Modes of detection have also evolved to in forensic applications should begin with classical AA improve sensitivity for a variety of matrices with these protocols. systems. They range from photomultiplier tubes (PMTs) Slavin.40/ credits a 1930 publication by Muller and or electrodeless discharge lamps (EDLs) used in conven- Pringsheim as the initial discussion of AA instrumenta- tional AA instruments to the charge transfer devices tion. This paper described the use of AA spectroscopy in (CTDs) found in inductively coupled plasma atomic the determination of mercury, an element that remains emission spectrometry (ICPAES) instrumentation. Some important in current literature..41/ The first articles ICPAES instruments still rely on PMT technology for that addressed the use of AA spectroscopy in foren- wavelength recording and enhancement. These systems sic applications, however, did not appear until the early are still quite useful for some applications and can reach 1970s..10,12,13,42/ These articles, which pertained to GSR comparable detection levels in certain well-defined matri- analysis, represent early examples of the use of mod- ces. Further evolution has produced inductively coupled ern atomic spectrometers in forensic laboratories. Before plasma mass spectrometry (ICPMS) instrumentation, this series of articles, GSR literature concentrated almost which utilizes either a quadrupole or magnetic sector exclusively on wet chemistry techniques..43/ detection system for mass-to-electric charge ratio (m/z) Forensic assays have recently focused on the organic determinations. nature of evidence. The most current forensic science Limits of detection for these various atomic methods review article by Brettell and Saferstein.44/ illustrates can range from microgram per gram (µgg1) to fem- the number of articles that characterize materials by togram per gram (fg g1) concentrations depending on their organic components. This review of forensic science the analyte of interest and the sample matrix..23/ Many publications also contains a section devoted to trace good general reference books have been written about evidence studies. It is interesting to note that there are AA spectroscopy, ICPAES, and ICPMS respectively. no atomic spectrometry articles listed for the surveyed However, for a practical introduction to each, Beaty and period that encompasses January 1994 to December 1996. Kerber,.22/ Boss and Fredeen,.23/ and Montaser.24/ are However, more than 300 references related to assorted useful for both beginner and refresher usage. atomic spectrometry applications appear in an April 1994

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 ATOMIC SPECTROSCOPY FOR FORENSIC APPLICATIONS 3 review published in the Journal of Analytical Atomic reference technique, results were reported for both major Spectrometry..45/ Moreover, many of these topics could and minor trace elements in several types of paint sam- be readily interpreted as forensic applications. ples, including automotive spray paint. A low pressure The publication of this type of research in a more nitric acid–hydrofluoric acid digestion mixture followed mainstream spectroscopic journal lends strength to by ICPAES yields comparable results to neutron acti- the argument that forensic science is simply applied vation data with equivalent relative standard deviations analytical chemistry. That it is performed as a service (RSDs) of approximately 5%. For studies that serve to to the criminal justice system is secondary to its associate the trace elemental compositions of two or nature as scientific analysis. For this reason, it is vital more specimens, this level of uncertainty is generally con- that forensic scientists also maintain familiarity with sidered to be acceptable. Furthermore, in comparative mainstream scientific literature, which often contains examinations, which is the basis of most forensic work, it articles regarding forensic topics. is more critical to develop associative information about Several papers that have concentrated on the use each of the known and questioned specimens than to of atomic spectroscopy in forensic applications were attempt to fully characterize the trace element profile of published in 1985 by Carpenter,.46/ in 1993 by Koons,.47/ any one specimen. Therefore, precision errors approxi- and by Lalchev et al..48/ in 1997. Each article focused mating 5% between replicate trials of a given specimen on the use of ICPAES for trace element patterns in have been deemed reasonable for this type of analysis. materials such as glass, brass, bullet lead, and elevated The article also mentions earlier work using AA and levels of toxic elements in animal tissues. These articles direct current plasma (DCP) spectrometry, which is demonstrate the range of materials that can be of forensic beneficial to readers who have access to this type of interest, a discipline rich in compositional diversity. instrumentation. Analytical instrumentation purchasing In this diverse environment, developing a preparation decisions in forensic laboratories are often based on method best suited for a given sample size and matrix is a practical budgeting rather than ideal conditions. As a prudent approach to any research study. Several journals result AA, particularly flame AA, remains a popular publish annual reviews to highlight articles that have technique. Part of its ubiquity is due to the plethora of been published in a given specialty. These sections are experienced technicians who can operate, maintain, and, generally grouped by application, with separate editions if necessary, repair such instrumentation. dedicated to general instrumental advances in atomic Virtually everyone with a physical science degree has emission,.49–53/ AA and fluorescence,.54/ and atomic mass had exposure to AA in some college course, internship, spectrometry,.55,56/ respectively. Perusal of these types or employment opportunity. Moreover, procedures for of review issues is a useful and inexpensive means of its use with many forensic sample matrices as well as its staying current with new instrumentation. Moreover, limitations and interferences are thoroughly documented journal sections that describe recent applications in in textbook literature. Thus, it is widely accepted in the environmental, industrial, clinical and biological materials forensic community. all contain novel sampling discussions that can be useful to Another reality of forensic work is that specimens are . / forensic analysts regarding these types of materials. 57–69 frequently received in less than ideal sample quantities As discussed earlier, there have been numerous or conditions. While the article by Paudyn and Smith.70/ forensic applications throughout the development of suggests an attractive forensic application, most eviden- atomic spectroscopy. The following sections will attempt tiary paint specimens are chips rather than scrapings. to discuss these topics in terms of the various analytical Moreover, comparison of such a complex matrix would methods that have been applied to a given sample type. most assuredly require a multielement examination tech- Some areas will show the evolution of the spectroscopic nique such as inductively coupled plasma (ICP) or DCP, techniques available for use. Others will demonstrate rather than the time-consuming single-element capability that ‘‘new’’ is not always improved, depending on a given of the traditional AA equipment found in most forensic sample matrix and analyte of interest. laboratories. It is also interesting to note that forensic applications which appear in mainstream atomic spectrometry journals 3 APPLICATIONS often cite the lack of available background information for the reported research. A 1998 paper by Zieba-Palus.71/ A 1993 article in the Fresenius Journal of Analytical published in Forensic Science International describes the Chemistry by Paudyn and Smith.70/ describes a proce- study of used motor oils by flame AA as a potential dure for the analysis of lead-based paint scrapings by forensic examination. The paper also notes that similar ICPAES after microwave assisted digestion. Using aque- work has been published by two separate groups using ous standards and neutron activation analysis (NAA) as a electrothermal AA spectroscopy and ICPAES. Both of

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 4 FORENSIC SCIENCE the latter techniques would be more desirable alternatives foods are not accepted from countries whose products to flame AA. Graphite furnace atomic absorption could damage domestic crops or place consumers at risk, spectroscopy (GFAAS) has detection limits about two due to inherent disease, insect infestation, or pesticides orders of magnitude better than either flame AA or used during their growing. This topic, as a novel example ICPAES. For its part, ICP is much faster at detecting of the diversity of forensic work, was also covered by the emission signals simultaneously or in rapid sequence. Washington Post.73/ and was presented by Schwartz,.74/ Moreover, the higher temperature of a plasma derived the research chemist who developed the protocol, at the excitation source allows for analysis of refractory metals. 1998 Winter Conference on Plasma Spectrometry held in Therefore, since this application could be developed Scottsdale, Arizona. for use with any of the aforementioned techniques, the Originally, this work was performed with ICPAES, but underlying considerations of adequate sample size and has been furthered using ICPMS. Decreased instrument predetermination of what conclusions could be drawn sampling time and improved sensitivity over a mass from the resultant data must still be assessed for each range comprised of 70 elements has allowed for more situation. For example, one must ask what probative specimens to be analyzed in a timely fashion. As a result value an oil spot on a suspected carjacker’s clothing would of the additional elements of interest and increased have if he were an automechanic. However, if the victim specimen throughput, better differentiation has been was a mechanic and the suspect was an office worker achieved between a larger number of samples. Thus, who had motor oil on his shirt, then the compositional discrimination by country of origin is possible based similarities between the victim’s work environment and upon a statistical modeling of the observed concentration the suspect’s stained clothing might prove to be significant differences between products from various global locales. corroboration of contact between these two individuals. To date, this work has been applied to imported raw Often, the circumstances of how transference of trace peanuts, garlic, coffee beans, and orange juice. evidence can occur need to be assessed prior to initiation Other articles have focused on the use of atomic of a potentially meaningless examination. spectrometric techniques for analyses of such diverse matrices as olive oil,.75/ plants,.76–78/ wine,.79–81/ milk,.82/ 3.1 Natural Products snow,.83/ and tobacco..84/ Given the current litigious climate surrounding tobacco and its by-products, the Natural consumer products manufactured and grown for ability to differentiate plant origins by trace element human consumption or use is another popular area of study in atomic spectrometry. The distinction between concentration levels would seem to be of interest to the what constitutes a clinical, environmental, or regulatory legal community. application versus one that is forensic often depends Similarly, an article in the Indian Journal of Forensic on the objectives of a given study. While none of the Science makes an argument that trace element composi- following publications was written to address forensic tion comparisons between ashed tobacco specimens can .85/ issues per se, it is not unreasonable to view these articles be made using copper, cobalt, chromium, and zinc. as a model for that future use. The article does not mention what type of standards were An article appearing recently in Today’s Chemist at used. However, use of commercially available plant and Work, a journal published by the American Chemical leaf reference materials in addition to aqueous solutions Society, described the role of the United States Customs would seem to provide adequate calibration and check Service in the analysis of imported foods..72/ Customs, standards. a branch of the US Treasury Department, oversees Another study that looks promising utilized ICPMS to enforcement of trade and tariff regulations. For several analyze minor and trace elements in cigarettes and raw .86/ years, this agency has utilized ICPMS for the analysis tobacco. Aqueous stock standard solutions, traceable of the trace element compositions found in various food to the National Institute of Standards and Technology products. Since these levels will vary depending upon (NIST, Gaithersburg, MD) were used along with standard where the product was grown, such data are a good reference material (SRM) citrus leaves as a check indication of the country of origin. standard. A total of 30 elements were analyzed, including This information aids Customs in several important some of the lanthanides and uranium. Rhodium (103Rh) commerce and food safety issues. First, the amount of a was used as the internal standard. No mention is made particular product from a given country is often regulated regarding selected isotopes or interference corrections, in accordance with trade agreements. Some countries are both of which are quite important in interpreting the further banned from trade with the USA as a result significance of the findings. Regardless, tobacco crops of sanctions. Likewise, tariff rates can vary between appear to be a promising area for continued forensic countries that import the same commodity. Also, certain research endeavors.

Trace element patterns in man-made fibers have also application featured analysis of major elements in the been explored as a potential forensic application of alkali and alkali earth series as well as iodine, barium, ICPAES..87/ This study focused on inorganic additives lead, and several light transition metals. Conclusions in polyester fibers. An earlier article also discussed resulting from the work emphasized the inhomogeneity of analysis of trace element distributions in several types the methamphetamine crystals studied, which therefore of commercially manufactured fibers using activation went on to require discrete multiple aliquot sampling analysis..88/ Comparing the two techniques as described per specimen. The article also notes that ICPMS was in these articles, NAA would appear to be a better attractive for its speed, and sensitivity. The inaccessibility alternative for this application given its sensitivity for of neutron activation beyond government laboratories intact 2-mg fiber samples. However, uncertainties of in the authors’ native Japan was also cited as a reason š20% are reported for major elements of interest, such for exploration of an alternative analytical method. A as Ti, Sb, Mg, Cu, V, Al, Cl, and Na. separate research interest was explored in the same In the former study, it is difficult to ascertain the year regarding the use of ICPMS for detection of trace success of the ICPAES methodology. Little attention elements in methamphetamine hydrochloride..90/ Many is paid to the use and development of the technique of the same elements were analyzed with NAA used as a itself. Rather, the focus of the article is the statistical reference method. manipulation that may be applied to the volume of More detailed papers using ICPAES and ICPMS sepa- data that was collected using ICPAES instrumentation rately or in concert for analysis of trace element signature of unknown manufacture and configuration. This article impurities in drugs of abuse appeared in the literature in therefore serves to highlight an unfortunate gap between 1995. In a paper authored by members of the National research and practical applications; that is to say, the Forensic Chemistry Center, the United States Food and ability to combine critical procedural details with useful Drug Administration Laboratory in Cincinnati, Ohio, applicative conclusions often remains an unrealized goal g-hydroxybutyrate (GHB) was analyzed by ICPAES for in forensic literature. The information gap between the the presence of Ba, Ca, Cd, Fe, K, Mg, Ni, P, Pb, Si, Sr, research scientist and the caseworking technician must and Zn..91/ The results were promising as a starting point be lessened if productive studies are to be implemented for identification of ‘‘contamination’’ elements that could in real time laboratory settings. This disparity is not serve as elemental pattern markers in sourcing batch exclusive to the forensic community. However, it is a production, manufacturing sites, or other discriminators scenario that demands attention within this discipline as that might lead to identifying clandestine laboratories. it continues to arise in evidence admissibility hearings. To date, however, it is unknown to the authors if any of New technology is increasingly being introduced into this research has been introduced in court. Recall that courtrooms, where it is placed under intense scrutiny. In the Daubert standard, with its four prongs to determine these Daubert hearings (the result of the Supreme Court’s admissibility – testing, validation, error rate, and general opinion in Daubert vs Merrell Dow Pharmaceuticals 509 acceptance in the scientific community – now applies to US , 113 S. Ct 2786), the weight of a technology’s all scientific evidence presented in US federal courts. evidentiary merits is evaluated. In this regard, it is Also described in this paper was the analysis of often easier to define the contribution of developmental ephedrine hydrochloride via ICPMS. The presence of research to the advancement of the larger scientific 14 elements including Na, Al, Mn, Rb, Sr, Ba, and Pt was community than to the smaller populations it attempts found to serve as a good discriminator between batches to serve. of ephedrine samples. Sodium later showed poor day- to-day reproducibility, although it had originally proved 3.2 Drugs of Abuse encouraging in same-day production trials. The authors theorized that this discrepancy was attributable to cross- Atomic spectrometry is clearly impacting upon one high calibration problems between the pulse counting and profile forensic application: the prosecutorial war on illicit analog detector modes in the ICPMS instrumentation. drug manufacture and trade. Five separate articles were Given their respective concentrations, detection of the found in nonforensic journals that detail the interest 14 analytes would likely split evenly between the two and capabilities of atomic spectrometric techniques in detector modes. Thus, this problem is nontrivial to atomic the analysis of drugs of abuse and their derivatives. As spectroscopists and yet not obvious to inexperienced users early as 1988, when ICPMS had only been commercially of the technique. available for approximately 5 years, an article in the Another ICPMS paper from 1995 detailed the analysis Journal of Chromatography described its comparative of trace elements in heroin..92/ The approach used for use to ion chromatography for detection of inorganic sample comparison resembled the paper described earlier impurities in organically pure methamphetamine..89/ This by Schwartz of the US Customs Service, in that the heroin

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 6 FORENSIC SCIENCE was analyzed for country of origin comparisons between would require a more thorough interpretation in order major producers such as India, Turkey, Iran, Pakistan, for the probative weight of the results to be assessed. Mexico, and Burma. Not surprisingly, Mexican data were quite different from the other countries in the study, 3.3 Suspected Poisonings which share a common geographical locale. Further, Iranian and Pakistani data were indistinguishable on the The distinction between environmental, clinical, and dendrogram of all analyzed samples. While this paper forensic applications is not easily delineated when is a nice representation of the power of ICPMS for discussing cases where poisoning is suspected. The use in multivariate statistical compilations, it is more methylmercury exposure of hundreds of Iraqi citizens useful for data processing than method development. in the early 1970s was attributed to ingestion of grain Conversely, studies such as Schwartz’s work can be an that had been treated with fungicides that contained .96/ essential component in comparative analytical research mercury. While the circumstances were extremely due to its description of the analytical method, equipment, unfortunate, the intent was not criminal. Similarly, and data interpretation steps. the chronic and acute arsenic poisoning of almost 75 Further controlled substance research utilized elec- consumers in Singapore of traditional Chinese medicines trothermal vaporization AA spectrometry for the analysis in 1975 was characterized by researchers as overuse of .93/ the product and poor quality assurance testing by the of Ag, Al, Cd, and Mn in cocaine and heroin samples. .97/ The charring step was omitted from this research in manufacturers. However, the presence of cyanide in Tylenol capsules in the USA in 1982 was attributable to favor of decreasing the sample pretreatment time. Higher an individual’s willful intent to endanger public safety. drying temperatures were studied, as were lower tem- Therefore, the results of an environmental offense may peratures in the presence of chemical matrix modifiers. often have similar consequences as those of crimes against The beauty of this work from the viewpoint of a bench either specific or nonspecific victims. Chain of custody chemist was its use of instrumentation that may already be issues and potentially limited sample availability, then, standard equipment in most forensic laboratories. How- strengthen the commonality in the analyses used for the ever, the challenges of adapting a procedure toward a respective investigations. given set of practical conditions including available instru- Atomic spectroscopy has long been utilized in bio- mentation and software options, sample design, operator logical applications that embody a general forensic experience, and time and budget constraints can repre- description. In one study, silicon, in the form of organosil- sent a potentially lengthy technical and logistical research icon oxide polymers, was analyzed by AA with a hollow effort. graphite tube assemblage..8/ This research was conducted A more recent application of ICPMS with regard to as a result of the use of silicone in breast implants. Similar analyses of drugs of abuse was introduced at the 1998 analyses regarding the chronic effects and environmen- .94/ Winter Conference on Plasma Spectrometry. It was tal impact of heavy metals on populations have also later described in the September 1998 issue of the Journal been conducted using emission spectroscopy..98,99/ Mer- .95/ of Analytical Atomic Spectrometry. Researchers in cury determinations by a variety of atomic techniques Australia have attempted to source the provenance of have also continued to span a wide series of forensic cannabis crops using LA/ICPMS. Elemental patterns of interests..100 – 104/ Moreover, the development of ICPMS crops known to be grown in different parts of western has generated tremendous interest in the levels of trace Australia were studied in an attempt to characterize elements in biological matrices..105 – 113/ A 1997 paper plant trace element compositions as a product of the even compared the potential of ICPMS versus NAA in soil environment from which they were harvested. Plant the multielement analysis of earthworms, as indicators specimens were freeze dried, pressed into disks and of ecotoxicological assessments and the bioavailability of ablated for sample introduction into a conventional ICP metals in soil..114/ mass spectrometer. Optimization of the instrumental Arguably, the greatest contributions that ICPMS has operating parameters was achieved using glass SRMs made to spectrometric studies have been in the areas commercially available from NIST. It is the author’s of elemental speciation and isotopic ratios. Specifically, conclusion that these data would be quite favorably arsenic and mercury speciation studies are of interest received by a jury of nonscientists due to the obvious to forensic analysts, and these topics have been well concentration differences that could be observed in plants documented in recent literature..114 – 123/ Lead isotope that were geographically isolated from one another. ratios are of particular interest due to the use of lead in However, the subtle differences that can occur in plants water pipes, paint, gasoline, and pottery. Isotopic ratios from similar regions, such as that noted in the data of of lead are often studied in an attempt to trace the lead heroin specimens from Iran and Pakistan previously cited, back to a specific source for both environmental and

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 ATOMIC SPECTROSCOPY FOR FORENSIC APPLICATIONS 7 archaeological purposes. If the lead is known to have was thought to have occurred. Bulk analysis of hair speci- been mined as a primary resource, rather than recycled mens can prove to be troublesome when multiple strands from a previous use, these ratios can provide useful are analyzed simultaneously because hair can remain information as to the isotopic composition of this lead attached to the scalp through several stages of matura- source. Compiling data from various lead mining sites tion. However, this process allows for a representative provides a compositional map that can be compared to sampling of the submitted specimen. Moreover, the solid the lead specimen under investigation in a given study..124/ sampling technique eliminated timely dissolution proce- Lead isotope ratios in modern-day goods such as ammu- dures and inherent contamination risks associated with nition would be of interest to the forensic community, and this sample preparation step. While this method is quite has been explored by several researchers. However, bul- useful for single element determinations, the sensitiv- let lead is not culled from a primary source. Rather, it ity and multielement capabilities of a technique such as is mostly harvested from recycled automotive batteries, ICPMS make it a more attractive alternative when the and therefore is not directly traceable back to its origins. constituents in a suspected inorganic poisoning case are Greater emphasis will be placed on this application in a unknown. later section. ICPAES has also been used for bulk analyses of metals One of the most popular biological matrices that has in cut head hair. However, the cited study determined been studied in suspected heavy metal poisoning cases concentrations for major (Na, Mg, Ca, and K) and first is human head hair..125 – 127/ This matrix is easier to row transition elements using a sample size of 800 mg. work with than most biologicals, in terms of sample Specimens of this magnitude are a rarity for forensic case .147/ preparation and analytically detectable element profiles, submissions. As with other applications, ICPMS has when analyzed in bulk. Elemental concentrations in hair created new and exciting possibilities for the examination can be as high as 300 times that of blood specimens, with of trace elements in hair. At least two papers describe recent exploration into environmental pollution effects microgram per gram quantities generally considered as an on cut, bulk head hair samples using ICPMS. A paper average baseline concentration..128/ Each cited reference from 1994 gave detailed sample preparation criteria and describes what a trace element examination of human hair instrumental parameters..148/ That work featured indium can reveal regarding the subject’s recent environment. as an internal standard, with emphasis placed on cadmium They also offer suggestions for sampling. and lead determinations. Levels of these elements and Much of the early analytical literature, which detailed several others, including arsenic, were monitored in hair potential differences between rate of hair growth in males as a bioindicator of exposure levels in smokers and versus females, elemental deposition along the length of nonsmokers. A separate 1998 publication described the a single hair, and, suspected poisonings, were studied .129 – 134/ method used to monitor levels of metals (As, Cd, Cr, Hg, using NAA. As with many types of specimens, the Mn, Ni, Pb, and Sn) in the hair of children in Spain..113/ ability to analyze several milligrams of a solid for up to 30 An internal standard was not used in the latter study, in elements simultaneously is an attractive feature of NAA, which arsenic and mercury analyses were conducted using assuming that adequate facilities are available for use. hydride generation rather than a conventional sample Analyses of hair have also been routinely performed introduction system for ICPMS. using AA methods, with detailed studies reporting arsenic Single strands of hair were analyzed for mercury and levels in hair as indicators of environmental exposure or thallium using ICPMS in a 1993 article by members of .135 – 145/ chronic poisoning. Such work was also conducted the National Institute for Environmental Studies (NIES) in the early years of suspected arsenic poisoning cases in Japan..149/ Flow injection which requires a small that were analyzed by the FBI Laboratory. However, the sample volume, typically 50 µL, was used for specimen advent of the graphite furnace gave way to the develop- introduction to the plasma. Each sample was segmented ment of a protocol that was instituted in 1994. Using this in 3–5 mm increments from proximal to distal ends of a procedure, individual solid head hair samples were placed single hair. A human hair certified reference material directly onto a graphite platform situated inside a hollow (NIES CRM No. 5) commercially available from the graphite tube. A chemical matrix modifier composed of NIES was similarly studied. Mercury was analyzed in palladium and magnesium nitrate was then instrumen- the hair of a healthy male whose baseline mercury tally pipetted onto the hair within the graphite tube..146/ hair content was observed to fluctuate over a period of NAA was used as a reference method. This work was of 6 months while he lived in Japan. The authors attributed great importance to the laboratory for several reasons. these data to an increase in fish intake in a subject Hair specimens, 5 mm in length, were oriented root-to-tip who prior to this timeframe had rarely consumed fish and segmentally analyzed in order to develop a theoret- as part of his daily diet. Hair from a patient who was ical modeling of a time line during which the poisoning known to have been poisoned with thallium was also

8 FORENSIC SCIENCE ) GFAAS versus ICPMS values in a suspected arsenic 1 800 Table 1 −

poisoning 700

g µ 600 Hair length Sample weight GFAAS ICPMS a

(cm) (mg) (ppm) (ppm)

500

ation ( 0–1 (root) 1.655 Not detected Not detected 400 1–2 1.500 (3) 7.8 š 0.6% 300 2–3 1.638 72 š 3% 64 š 0.6%

3–4 1.631 (5) 4.2 š 1%

200 4–5 1.536 81 š 2% 74 š 0.4%

100 5–6 1.544 490 š 0.4% 458 š 0.6%

As concentr

6–7 1.365 (1) 2.7 š 3%

1 7–8 1.245 Not detected 9.6 š 2% 2 3 4 5 6 7 8 9 − 11 − − − − − − − − 10 12 13 14 0 − š š 1 2 3 4 5 6 7 8 − − − − 8–9 1.103 38 15% 41 1% 9 10 11 12 13 9–10 0.850 Not detected 3.6 š 3% Length of hair in cm (root-to-tip; 10–11 (tip) 0.506 110 š 14% 124 š 0.6% 29 days/cm growth) a Approximately 25–50 head hairs in each segment.

Figure 1 Chronic poisoning occurring over the course of 1 year. method and discussions with Wallace.150/ of Perkin- Elmer, it is now thought that concerns regarding the analyzed. Specimens were collected 3 weeks after he was introduction of chlorine from the hair matrix are µ 1 hospitalized. Levels of 35 gg were detected in the unfounded given that the hair is thoroughly washed and peak section of the hair sample, with the lowest levels rinsed in alcohol prior to analysis. However, if continued µ 1 (¾3 gg ) also exceeding predicted normal thallium monitoring for chlorine is desired, a better gauge of its µ 1 levels (0.016 gg ). It was theorized that the patient presence would be observation of the selenium isotope had been exposed to thallium from as early as 8 months at mass 77, where 40Ar37Cl would be observed as an prior to this sampling study, which was conducted 3 weeks interferent. Similarly, selenium at mass 82 should be before his demise. monitored for comparison to Se-77. In the Spring of 1998, the FBI Laboratory received two Agreement between the two atomic methods was not suspected arsenic poisoning cases within weeks of one as good as expected. Concentrations differed by as much another. The decision was made to develop a protocol for as 10–30% between the GFAAS and ICPMS data. ICPMS in anticipation of eventually using this technique Results derived from the conventional AA procedure for multielement, heavy metal screening purposes. This were therefore reported, given that this protocol was course of action proved to be particularly timely when the better defined and validated. Table 1 lists the values hair of a cohabitating suspect in one of these cases was obtained for both methods in a representative suspected later submitted in order to rule out environmental factors, poisoning case. after the victim’s hair was found to contain elevated levels Subsequent cases were analyzed as bulk specimens due of arsenic. Figure 1 represents data from a typical chronic to a lack of sample. Both the aqueous AA and ICPMS poisoning event that was calculated to have occurred over protocols were utilized for these cases as well. The AA the course of 1 year. data were used as the reported method while development The two original submissions were first analyzed by work continues on the ICPMS procedure. the single solid hair segment protocol developed for GFAAS noted earlier. These analyses did not yield 3.4 Lead Applications the expected results, based on details submitted by the contributors in each of the two cases. Therefore, ICPMS Using conventional mass spectrometry equipment, lead was attempted on bulk hair segments, with solution AA isotope ratios have been discussed in analytical literature also performed on the digested samples as a reference since the mid-1970s..151,152/ This type of research was method. Aqueous arsenic standard concentrations ranged first published as applied work in specific fields of from expected normal arsenic levels of roughly 0.04 µgg1 study that sought to trace lead based objects back to up to 64 µgg1. Indium (115In) was used as an internal an original source. An article from 1976 appearing in standard. Archaeometry discussed the lead isotope ratios in artists’ Two isotopes of chlorine (35Cl, 37Cl) were monitored lead white pigment..153/ This material is ubiquitous in for comparison to the expected argon chloride (40Ar35Cl) paint media, but its isotopic ratio information has the interference on the lone naturally occurring arsenic potential to aid archaeologists in the characterization and isotope at mass 75. After repeated analyses with this source identification of specific production lots. An earlier

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 ATOMIC SPECTROSCOPY FOR FORENSIC APPLICATIONS 9 paper from 1975 introduced the concept of analyzing lead groups depending on the manufacturer’s protocol for ratios in bullets for the same purpose..154/ Similar studies loading cartridges into lots for distribution..158/ have been carried out more recently..155 – 157/ The original Several forensic laboratories have investigated com- paper by Haney and Gallagher.154/ noted that previous positional bullet lead analysis in research efforts using work had been done in this area for archaeological ICPMS..159 – 161/ However, ICPAES remains the preferred and environmental purposes. However, archaeologists method for this type of examination in the FBI Labora- traditionally analyze lead pigment from a time when tory’s Materials and Devices Unit, where hundreds of trade and travel was conducted along specific routes these analyses are performed routinely each year..162/ that can be usefully mapped. Also, the production of The FBI’s standard protocol utilizes seven trace elements this material was limited. Neither scenario applies to to compositionally differentiate between lots of bullet modern-day manufacturing processes. lead: Sb, As, Cu, Bi, Ag, Sn, and Cd. Triplicate samples ° Ammunition manufacturers estimate that current pro- of each specimen are digested in 20% HNO3 in an 80 C duction rates yield approximately 9 billion bullets per oven for 4–5 h. After removal from the oven, most speci- year. This number does not include lead used for shotshell mens are already a homogeneous solution; however, as a µ pellets. Another complication is that the four leading final aid to the digestion process, 10 L of reagent grade ammunition manufacturers in the USA routinely obtain HF (49%) is added prior to analysis. Specimens are run lead ingots from common distribution sources. Moreover, against a calibration curve that includes a 99.99995% lead this lead is not from an original source either. Bullet lead blank standard. is recycled from sources, such as automotive batteries, Three SRMs commercially available from NIST are which may be doped with manufacturer specified levels run in triplicate as check standards against this curve. The of antimony at a smelting facility and then shipped to the described method has been employed for over 10 years respective ammunition producers. Trace element concen- in the FBI Laboratory. During that time, recorded values trations in the recycled lead are generally not a concern for the stated SRMs have varied within an acceptable for bullet manufacturers, so long as the majority of the margin of relative error from those concentrations listed on the certificates issued by NIST. A reference database product is properly formed and passes routine quality is utilized to store this information regarding repeated assurance test firing. analyses of the SRMs. It is comprised of compositions With the exception of increasing automation, bullet that have been recorded using NAA, and three different manufacturing has not changed significantly since mass ICPAES instruments, with quantitative information for production became popular during World War I. Lead Bi, Sn, Ag, and Cd resulting from ICPAES analyses only. ingots are purchased from a recycling facility that smelts Figures 2–4 illustrate the average precision obtained for the lead into a manufacturer’s specified alloy that may arsenic, antimony, and copper, respectively, in SRM contain up to 3% antimony for hardness. Each ingot, 2416: Bullet Lead (NIST, Gaithersburg, MD) during 30 referred to as a ‘‘pig’’, weighs about 60 pounds. Pigs are melted in a batch process that allows for a continuous supply of the molten product to be solidified into billets, Avg (AII) SD (AII) 0.0549 0.0023 weighing about 125 pounds each. The billets are then 0.640 forced through a die of specified diameter to form wire, Certified value from which the individual bullets are cut and shaped. 0.620 0.056 The uniqueness of each batch of lead is a result of the 0.600 +2 SD (AII) c continuous addition of ingots and recycled scrap lead i 0.580 +1 SD (AII) n back into the primary cauldron or melting pot. A batch e 0.560 Avg (AII) s is thus determined by the size of a given manufacturer’s r 0.540 −1 SD (AII) A

.158/ ﬁnal melt. 0.520 −2 SD (AII) The formed bullets are only one component of the % 0.500 As (last 30) ﬁnished product known as a cartridge. Once the bullet is placed in a cartridge case that houses a primer cup 0.480 and gunpowder, the assembled cartridges are packaged 0.460 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 in sets that range from 20 to 100 per box. Lot numbers are 9 1 1 1 1 1 1 1 / / / / / / / 8 4 2 6 9 6 assigned at the time of cartridge assembly and packaging. 8 2 0 1 2 0 1 0 / / / / / / / 4 5 5 5 6 6 Therefore, hundreds of boxes may have the same lot 7 0 0 0 0 0 0 0 number. Due to the mixing of formed bullets prior to Date assembly and packaging, a single box has been observed to contain up to 12 unique trace elemental composition Figure 2 Average precision obtained for arsenic.

Avg (AII) SD (AII) residues left behind from a cartridge’s primer com- 0.7941 0.0163 ponents. Organic residues derived from unburned or 0.8800 partially burned gunpowder are referred to as gunpowder Certified value 0.8500 0.79 GSR. Both species are associated with the discharge of a +2 SD (AII) ﬁrearm. Therefore, GSR analyses are performed in order y 0.8200 +1 SD (AII) to determine if an individual or an object was in the vicin- Avg (AII) ity of a ﬁrearm at the time of its discharge. Currently, 0.7900 −1 SD (AII) the most common techniques used for this examination − 0.7600 2 SD (AII) are AA spectrometry for bulk analysis of swabbed areas

% Antimon Sb (last 30) and scanning electron microscopy (SEM) examination of 0.7300 dabbed surfaces for particle analysis..38/ The presence of GSR indicates that a weapon was ﬁred. 0.7000 GSR examinations are used to determine if the ﬁrearm left behind detectable amounts of inorganic residue on surfaces in the vicinity of the discharge or surfaces with

04/26/1999 05/03/1999 05/05/1999 05/12/1999 05/21/1999 06/01/1999 06/09/1999 06/16/1999 07/07/1999 07/08/1999 which the ﬁrearm was in direct contact sometime after its Date discharge. The results cannot determine the caliber of the weapon used, nor does it identify the shooter. Figure 3 Average precision obtained for antimony. Subsequent handling of a discharged weapon would be an example of GSR deposition through surface Avg (AII) SD (AII) contact. Assuming normal activity, GSR is not likely 0.06482 0.00181 to remain in detectable concentrations on a surface 0.07250 6–8 h after a weapon’s discharge. Common sampling Certified value surfaces include objects at a crime scene and the hands or 0.07000 0.065 clothing of a person who may have been at the scene at +2 SD (AII) r 0.06750 the time of the weapon’s discharge. However, if GSR

e +1 SD (AII) p 0.06500 Avg (AII) is not detected, no conclusions may be drawn from p .164/ o −1 SD (AII) this test.

C 0.06250 −2 SD (AII) Research is currently in progress to bring GSR testing

% 0.06000 Cu (last 30) back on-line for a limited number of approved cases 0.05750 within the FBI Laboratory. The techniques that will be employed are SEM and ICPMS. The latter technique 0.05500 will serve as a screening process for the proper ratio of 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 three elements that define the presence of residue from 1 1 1 1 1 1 1 1 1 1 / / / / / / / / / / 6 3 5 2 1 1 9 6 7 8 a discharged weapon: antimony, barium, and lead. If 2 0 0 1 2 0 0 1 0 0 / / / / / / / / / / 4 5 5 5 5 6 6 6 7 7 the ICPMS results are conclusive, particle analysis using 0 0 0 0 0 0 0 0 0 0 SEM will be performed to detect the presence of primer Date particles. Figure 4 Average precision obtained for copper. One of the first GSR test methodologies to be published was the paper by Harrison and Gilroy.43/ in 1959. There are still a handful of new applications in modern separate analyses of this SRM in the FBI Laboratory. day literature despite the controversy surrounding what Each graph depicts the mean and first and second conclusions may be drawn from the examination..165,166/ standard deviations obtained for the respective elements For example, there is little scientific need to perform a as a function of the date on which the analysis was GSR study on a victim who has been shot. Similarly, some performed. These control charts serve as instrumental 0.22 caliber ammunition does not contain antimony in the response monitors for the three main elements of interest primer, which is a reality that the forensic scientist must in the comparative bullet lead methodology..163/ be aware of in order to properly interpret the data from this test..10/ 3.5 Gunshot Residue Analysis While early publications detailed appropriate wet chemical methods for GSR detection, many subsequent A much more common forensic examination involving articles were published beginning in the 1970s, which fired ammunition is primer GSR analysis. GSR for the focused on the promise of new or combined techniques for purposes of this treatise is described as the inorganic this analysis..167 – 176/ Drawbacks to these methods include

NAA’s inability to detect lead and flame AA’s lack of addition to previous research in 1989 that described the sufficient sensitivity for barium and antimony. However, use of flameless AA spectroscopy and ICPAES using an flameless AA applications were quite promising for the updated swab extraction procedure..172/ Most recently, advancement of GSR studies involving all three elements a 1998 publication details the protocol under investi- of interest. In 1987, three papers were published that gation by the FBI for the use of ICPMS as a bulk demonstrated the popularity of GSR research by a variety screening technique prior to the use of SEM/EDX for of techniques..168 – 170/ particle identification..166/ With proper sample collection, The first paper described a procedure whereby gun- including consideration of the timeframe for sample col- powder stabilizers were analyzed by high-performance lection and requisite environmental conditions necessary liquid chromatography for their organic content followed for a valid analysis, ICPMS screening for the presence of by GFAAS for the characteristic presence of barium, anti- GSR will offer significant time savings in the examina- mony, and lead. In a typical forensic laboratory, it would tion process. If ICPMS results produce cause for further seem as if this dual approach could be time-consuming study, SEM/EDX can be employed for verification of the and costly. Moreover, the results were not necessarily presence of specific GSR particles. more compelling than AA measurements alone, given The FBI Laboratory’s ICPMS research protocol for the extra time involved as weighted against information GSR was developed on the basis of years of experiments gained from the double analysis..168/ using flameless AA sample collection, storage and anal- The second paper investigated the use of Auger ysis. Early models included publications by Triplett,.176/ electron spectroscopy as a substitution technique for Gonzales,.177/ and a study by Vandecasteele et al..178/ energy dispersive X-ray analysis (EDX)..169/ The authors The latter article described elemental concentrations that described this alternative as a means of depth profil- were found to be present in air samples collected in ing the layers of particles of interest. Better lateral an indoor shooting range. Such studies provide essential resolution and peak differentiation were also cited as background information as to the levels of GSR that advantages over EDX measurements. However, this can be exhibited by persons in close proximity to a dis- argument does not seem compelling in light of the number charged firearm, even if the individual has not actively of scanning electron microscopy/energy dispersive X-ray engaged in the discharge of a weapon. The 1998 paper analysis (SEM/EDX) papers that continue to appear in by Koons.166/ in the Journal of Forensic Science lists the the literature. Comparatively speaking, Auger electron solutions, method and instrumental conditions employed spectroscopy does not decrease the time constraints of in this pilot study. GFAAS and ICPAES were used as the examination, instrumentation costs are higher than control methods of analysis for this work with comparable for SEM/EDX, and a multitude of problems were quickly results being realized from all three analytical techniques. associated with the carbon planchet collection stubs when A further interest in the development of this protocol is compared to those used for EDX. currently two-fold. There is a desire to characterize other The third article that was published in 1987 made elements associated with specific primers or ammunitions. an argument for the use of SEM/EDX exclusively for For example, future work may include the study of GSR analyses..170/ The opening paragraph acknowledged strontium in nontoxic primers. that the current method of choice for GSR was a bulk Another publication of merit in the analysis of GSR analytical approach in which NAA (for barium and by a variety of spectrochemical methods was published in antimony) and AA (for lead) were used in concert. In 1997 by Meng and Caddy..165/ As a review article, it is a fact, this procedure was employed by the FBI Laboratory comprehensive analysis of the history of this examination, at the time of the publication. The paper argued the with information on the composition of primers and the merits of defining the morphology of a particle as being myriad of techniques available for study of the residues consistent with GSR as opposed to using AA to quantitate produced. While the discussion leans toward an argument elements that were readily found in nature. Indeed this in favor of analysis of the organic components in GSR, rationale has been adopted by many laboratories so that it is nonetheless a comprehensive treatment of the many the majority of modern GSR analyses are performed considerations that play a role in this examination. almost exclusively by SEM/EDX. Extensive studies have been performed in this area by the FBI Laboratory as well. As one of the premiere foren- 4 METALS ANALYSIS sic laboratories in the world, there has never been a lack of funding or research talent to promote innovative sci- 4.1 General Applications entific advances within the forensic community. Work by the FBI Laboratory in the area of bulk GSR examinations Another area of analytical endeavor that has embraced included a published hand-blank study from 1990,.174/ in the development and increasing availability of ICPAES

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 12 FORENSIC SCIENCE is the metals industry..179/ The ability to monitor and In a 1993 article, Wynn.184/ discussed a dissolution thus control elemental impurities in industrial alloys has procedure for tin–lead solders using a combination of made it possible to discriminate between these objects nitric and hydrochloric acids for detection of both trace for forensic purposes as well..180,181/ Nonhomogeneous and major elements using inductively coupled plasma leaded brass (copper–zinc alloys) studies were published optical emission spectroscopy. The procedure utilized a in 1985..180/ Sample sizes of 10–100 µg were found 1-g sample size, which was digested by the acid matrix on to be adequate for ICPAES analyses..181/ However, an open hotplate in about 15 min. Calibration standards specimens of 20 mg in triplicate were used for a similar were comprised of purified solid tin and lead standards, study involving common household aluminum foils. This digested in the acid media for matrix matching purposes. material is of interest to forensic scientists due to its Similarly treated SRMs from NIST were used to verify prevalence at crime scenes involving narcotics production the standard solution concentrations. or the assemblage of improvised explosive devices. The Differences between the obtained ICP results and the elements of interest in this initial study were Cu, Fe, NIST certified values averaged about 10%. This work is Ga, Mg, Mn, Ni, Si, Ti, V, and Zn. Analytical precision of particular interest in this forensic laboratory because of was determined to be about 1–2% RSD for most of the the frequently encountered domestic terrorism bombing studied elements. cases in which solder features in the construction of Further work on aluminum alloy trace element patterns improvised explosive devices. If signature trace element has been reported using ICPMS and glow discharge mass patterns could be developed to source solder back to a spectrometry by Feng and Horlick..182/ The ion source unique origin, this information would serve as a powerful for the glow discharge measurements was a substitution investigative tool. of the plasma sample introduction system found on Scientists at the University of Pretoria published a 1996 conventional ICPMS instruments. While this approach article in the Journal of Forensic Science describing the use is still more research oriented than applied, using ICPMS of ICPAES for the study of trace element compositional for this examination is noteworthy. Moreover, the article differences in mild steel..185/ This material is an iron-based provides good background for scientists interested in alloy containing manganese and carbon in quantities that pursuing laser ablation studies of solid metal samples. are difficult to detect and quantify using other methods. The advantages and disadvantages of sample dissolution The authors explain that mild steel is quite prevalent as ICPMS measurements are described in relation to laser a construction material for storage objects such as safes. ablation analyses. A common mode of entry into these structures is to cut Since laser ablation is likely to remain uncommon through the container with an oxygen–acetylene torch. in forensic laboratories for some time, a 1998 paper While X-ray diffraction can distinguish the use of a torch by Coedo et al..183/ is helpful for its discussion of boric from an abrasive cutting tool via oxidation effects, it is acid as an aid in fluoride detection in steels via ICPMS. not as sensitive to trace levels of impurities in the steel. The dissolution involves microwave digestion of the This paper further describes the process whereby specimens for rare earth analysis using flow injection ICPAES can be used to relate metallic debris found for sample introduction into the plasma. As has been on a suspect to the cut object at a crime scene. First demonstrated for years by archaeologists using NAA and row transition metals were analyzed in two rods of mild more recently, ICPAES and ICPMS for trace analysis, steel as a test case. Four specimen aliquots were assayed the rare earth elements offer exceptionally consistent from a total drilled sample weight of 180 mg. Specimens concentration patterns. For this reason, they have served were digested in a hydrochloric acid–deionized water historically as unblemished geographic markers for (40 : 30 v/v) matrix. The signal from each analyte of sourcing production sites. interest was ratioed to the intensity of manganese, as A feature of flow injection analysis that may increase it is the most abundant alloying metal present in mild interest in the forensic community is the small sample steel. It was concluded that silicon and aluminum could volume needed for analysis. Load volumes are typically not be reliably distinguished using this method of analysis; of the order of microliter quantities. Moreover, the limited however, chromium, nickel, cadmium, zinc, and copper in exposure of the sampler and skimmer cones, in the ICPMS cutting debris could be sourced back to the parent sample instrument, to the highly concentrated salt solutions that when expressed relative to the intensity of manganese in typify such matrices improves precision measurements the specimen. because a steady state signal is readily achieved. As a routine application, the technique developed in this study 4.2 Precious Metals is relegated to the distant future. However, knowledge of its existence is of benefit to front-line forensic laboratories The use of ICPMS to study natural silver artifacts was where new challenges are often encountered. reported by Longerich et al..186/ in 1987. An argument

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 ATOMIC SPECTROSCOPY FOR FORENSIC APPLICATIONS 13 is made for the use of ICPMS as a sensitive analyti- analytical determinations..189/ Detection of phosphorus in cal tool that yields useful trace element compositional high purity iron (steel) specimens has also been reported information on small, often nonhomogeneous specimens. via electrothermal vaporization ICPMS..190/ Twelve elements were studied via ICPMS with compar- The most recent alternative that has been developed for ison data obtained for cobalt, nickel, copper, and zinc solution nebulization ICPMS where ultra trace analyses using flame AA spectroscopy. While rare earth elements are required is the collision cell..191/ This reaction were not targeted in this study, lanthanum contamination chamber may be either a quadrupole or hexapole that was observed as a result of its ubiquity in the given labo- is placed before the conventional quadrupole detector ratory environment. Moreover, two silver–argon species in an ICPMS instrument. Its purpose is to allow for an C C (107Ag40Ar and 109Ag40Ar ) were identified at masses inlet whereby a previously chosen gas will be introduced 147 and 149, respectively. These two isotopes would to the transported ions in order to form competing be of interest if samarium were to be included in the reactions with interferents of the analyte of interest. study. The absence of other rare earth elements such In this way, determinations such as that for calcium as cerium, neodymium, and europium supported the at mass 40 are possible when the potential argon discussed conclusions regarding the observed interfer- interference is eliminated by its preferential bonding with ing intensities at masses associated with lanthanum and the reaction gas. samarium. Similarly, the mass filter portion of this chamber sets Memory effects were also discussed in this paper. High a window through which only the analyte of interest acid content (0.8 M nitric acid versus 0.2 M) and a high is able to pass into the conventional quadrupole mass dissolved solids ratio were cited as contributors to this separator under the specified conditions. The obvious problem. One resolution would be frequent cleaning first-generation users of such advanced technology would or replacement of the sampler and skimmer cones that be the semiconductor industry in which high purity acids separate the air/vacuum interface between the ionization are required for production use..192/ Environmental and source and the detector. An alternative for stabilization biological uses are also facilitated by the collision cell’s of the signal prior to analysis would be to introduce a ability to characterize, for example, chlorine, selenium, slightly more concentrated solution of a given matrix in and lead isotope ratios..193,194/ order to achieve a steady state layer of solid material As stated earlier with regard to arsenic in hair analyses, on the cone surfaces. This method would apply more chloride levels are not thought to be a significant analyte specifically to a dedicated instrument or set of sampling interferent for prewashed hair specimens. Therefore, and skimmer cones, where such luxuries are available. such technology as the collision cell chamber would Related articles that further develop the concept not be warranted for this examination on a routine of ICPMS as a tool for the analysis of precious basis. Moreover, the instrument design is such that only .187/ metals have since been published. High purity highly pure solutions may be analyzed in this manner, a metals (cadmium, copper, gallium, and zinc) were requirement that perhaps disregards forensic specimens analyzed for 30 trace elements using high resolution by definition. However, it is an advancement of note for .188/ ICPMS. High resolution ICPMS utilizes a magnetic potential future applications..195/ sector mass spectrometer such as that employed in thermal ionization and spark source mass spectrometry instruments. Conventional ICPMS instrumentation is equipped with a quadrupole mass analyzer. In high 5GLASS resolution ICPMS, a quadrupole is utilized as a mass filter prior to sample introduction to the magnetic As with metals, glass is a material that has been sector spectrometer. This configuration can achieve mass studied from a multidisciplinary perspective. Its trace resolution of the order of 0.1 of an atomic mass unit element profile is of interest in manufacturing, both for certain elements. Mass discrimination in the presence from an historical and an industrial perspective..196/ of overlapping isotopes at this level of detection would Given the types of glass used to manufacture window serve the forensic community in applications such as panes in homes, offices, and automobiles, as well as, compositionally sourcing wires found in lamp cords used its use for headlamps, flashlights, and costume jewelry, to bind a victim, or in improvised detonation devices. compositional analysis is also of interest in the forensic Precious metals such as platinum group elements and community. As the manufacturing process is refined and gold in geological materials have also been analyzed tighter quality control limits are set, refractive index by ICPMS..187/ As an alternative to conventional fire differences continue to diminish between batch lots of assay methods, ICPMS offers a cleaner and safer sample container and float glasses. In cases where only small digestion environment in addition to greater sensitivity in fragments of glass are available for comparative analysis,

Encyclopedia of Analytical Chemistry, Online © 2006 John Wiley & Sons, Ltd. This article is © 2006 US Government in the US and © 2006 John Wiley & Sons, Ltd in the rest of the world. This article was published in the Encyclopedia of Analytical Chemistry in 2006 by John Wiley & Sons, Ltd. DOI: 10.1002/9780470027318.a1110 14 FORENSIC SCIENCE trace element patterns become critical for a relational ICPAES was further utilized for the study of an assessment to be made between known and questioned additional 232 samples using Mn, Fe, Mg, Al, Sr, and Ba. specimens..197/ Sample selection was represented by 10 narrow ranges Early work in this area was carried out in 1970 using of refractive index within the range of 1.5150–1.5210. NAA to distinguish between glass specimens from vehi- Each of these 10 groups of sheet glass specimens were cles involved in a two-car collision. Based on the NAA assessed for the overall discrimination capabilities of this results, glass transfer was found to have occurred between six-element composition assay. The author concluded the victim’s shattered Jeep windscreen and the carriage that the six-element compositional analysis coupled with of the truck that hit it. The truck fled the scene and the refractive index measurements was a better discriminator Jeep’s driver was killed in the collision. The truck’s driver than refractive index alone. However, better analytical denied both knowledge of the incident and his truck’s precision of the ICPAES technique was needed to further involvement in the accident. However, glass debris found improve discriminating ability between certain regions of on his vehicle compositionally matched glass specimens refractive index..201/ collected from the Jeep’s windscreen, indicating that these A 1987 article by the same author furthered this re- two vehicles were in contact at some point..198/ search into the use of multivariate statistical classification Glass analysis was subsequently discussed from the for ICPAES glass data..202/ An internal standard was perspective of atomic spectrometry by Hughes et al..199/ added to this study in which both discriminant analysis and in 1976. Both flame and furnace AA were used in cluster analysis were used. Other models such as Bayesian their research for the determination of manganese and statistics were also discussed as alternative classification magnesium. These elements were selected as useful treatments for this type of sample matrix and analytical discriminators between the following selected glass method. types: sheet, container, tableware, and headlamp glass Also published in 1987, Koons et al..203/ described specimens. Given the technology that exists today, this similar work that was carried out in the FBI Laboratory procedure would serve as the most basic of elemental using pattern recognition with ICPAES for classification screening tests. However, the article does provide useful and discrimination of sheet and container glasses. A background information regarding the process of sample 1991 article further developed the chemical discriminating discrimination, digestion, and early sample homogeneity capabilities available for glass samples with the inclusion results for common glass types..199/ of energy dispersive X-ray fluorescence to research This article was cited and expanded upon by Catter- involving refractive index and ICPAES..204/ These studies ick and Wall.200/ from the Metropolitan Police Forensic have led to the exploration of ICPMS as an analytical tool Science Laboratory (MPFSL) in the UK in a 1978 pub- for glass samples..205 – 207/ lication that included iron as an element of interest..200/ The first article of note in this area was published The described digestion was unique in that it substituted in 1990..205/ It described the dramatic compositional the heating of small fragments with a 30-min ultrasonic differences that exist between glass specimens from treatment. A combination of these two practices along the USA and Australia. Discrimination was defined with the use of both hydrochloric and hydrofluoric acids between two samples as a measure of overlap for any is now a generally accepted digestion procedure. element within a mean confidence of two or three Research into trace element characterization of glass standard deviations. If no such overlap occurred for types using ICPAES continued at the MPFSL. As the the elements of interest, the samples were considered method was refined and more elements were successfully to be distinguishable or separate in composition. Such added to the list of possible discriminators, interest shifted conclusions were based on mean concentrations obtained to what conclusions might be based upon trace element from five independent samples for both control and patterns in a given class of these specimens. Another suspect glass specimens. Sample sizes as small as 500 µg scientist at the MPFSL, Hickman,.201/ discussed the merits were utilized, with the mean sample size ranging between of glass classification in a 1983 article. 800 µg and 1200 µg. The concentrations of 48 elements Hickman worked with archaeologists and long-time were quantified in this study with RSD values of 4% neutron activation researchers, Harbottle and Sayre, at or less. Brookhaven National Laboratory in New York, to ascribe Fifteen trace elements were identified as discriminators meaning to the voluminous data that had been collected of float glass specimens, such that origin and further subset to that point. Using ICPAES for Mn, Fe, Mg, Al, Sr, classification was possible for individual samples. It was and Ba, NAA for Na, Cs, Sc, La, Ce, Eu, Th, Cr, Se, U, concluded that Australian glasses are better characterized Ca, and Zn, flame emission for K, Rb, and Li, and AA by ICPMS than ICPAES when a single technique is spectroscopy for As, 15 colorless sheet glass samples were preferable, due to the presence of trace elements at analyzed. nanogram per gram levels in the samples. However,

ICPAES can accomplish this same task in glasses for depth penetration studies depending upon the user’s manufactured in the USA, where trace elements are intent. typically three orders of magnitude more concentrated in Sample pretreatment usually involves the removal the matrix (microgram per gram quantities)..205/ of surface contamination with the laser system prior Parouchais et al..206/ supported this conclusion in a to collection of quantitative samples. Determinations 1996 paper in the Journal of Forensic Sciences.Itwas of the amount of material ablated with each laser further stated that samples sizes of 100 µg were necessary pulse have also been extensively discussed in the to adequately analyze headlamp specimens, while double literature. Differential weighing is most convenient that amount was needed for container and sheet glass. with adequate weighing apparatus as long as sample Using conventional solution nebulization technology, the positioning is not critical. However, transport efficiency authors concluded that the minimum sample volume is not factored into this equation and therefore must necessary for current ICPMS instrumentation would be be assessed using some other criteria, such as internal of the order of 2 mL. However, a precision of 1–5% standardization..217/ RSD would require a minimum sample volume of 5 mL An example of industrial interest in laser ablation was for a 1 mg mL1 glass solution..206/ It can often be a demonstrated when semiconductor companies sought to difficult task to achieve this sample size in forensic quantitate the level of actinides in aluminum used to cases. Thus, solid sampling is of great interest, both create integrated circuitry. As a quality control issue, this as a microanalytical technique and for its preservation research was given a high priority, so that LA/ICPMS of specimen integrity. Specifically, the coupling of laser was aggressively studied and found to be ideally suited ablation sampling with the sensitivity of ICPMS detection for this task..218 – 221/ For forensic purposes, this research has generated widespread attention in the pursuit of serves as a basis for LA/ICPMS studies of a variety of forensic applications..207/ metal objects used in the commission of a crime..222/ Simultaneously, academic researchers became interested in laser ablation as a geochemical sampling tool for the study of minerals. Geological studies by Jarvis 6 LASER ABLATION and Williams and others serve as good examples of early precious metal applications..223 – 225/ Subsequent studies Ten years after the commercial development and of LA/ICPMS by Watling et al..226/ have yielded trace widespread availability of ICPMS instrumentation, its element characterization of diamonds and their indicator early proponents were actively seeking the means to minerals, namely garnets and chromites. From this work expand its versatility. Dissolution requirements of con- and similar research, forensic interest was generated in ventional nebulization technology greatly detracted from the prospect of analyzing evidential glass fragments a the appeal of ICPMS. Therefore, nondestructive solid priori..227 – 233/ sampling methodologies were independently pursued in Early studies discussed the merits of ablating a solid both academia and industry for semiquantitative and material that had been added to a flux mixture and quantitative analysis of subpicogram per gram levels fused to a glass bead..217/ Particular attention was paid of trace elements in inorganic matrices of limited sam- to the use of a matrix element as an internal standard, ple size..208 – 216/ From this work evolved the concept of which is a convenient calibration strategy in homogeneous directly introducing solid material to a plasma ionization specimens. The application of this method to the study source. of rare earth elements in geological materials was further Lack of dissolution provides better sensitivity due to the discussed, with detection limits reported in the range absence of polyatomic species generated by the aqueous of 0.02–3 µgg1. The significant reduction of polyatomic medium necessary for conventional nebulization. Speci- interferences as compared to solution nebulization was men size requirements are significantly reduced with solid also noted..217/ sampling; therefore, the sampling process can be virtually Further interest in the use of LA/ICPMS for forensic nondestructive to rare or evidential materials. casework has since been generated by the continuation Basic explanations of the theory and evolution of laser of promising work in this area from researchers at the ablation sampling as related to ICPMS may be found in Chemistry Centre of Western Australia..234/ This group these literature references. However, the popularity of first reported on the use of LA/ICPMS for trace element the technique has resulted in its discussion in a recent determinations in cannabis plants as detailed in an earlier textbook as well..24/ Most commercial systems employ an section. That work developed from promising results for Nd : YAG laser at a wavelength setting of 1064 nm, which similar studies using steel and glass specimens found emits a pulsed signal of 500 mJ for sampling purposes. at crime scenes. These analyses were reported on in The laser may be rastered across a surface or used the Journal of Analytical Atomic Spectrometry in early

1997..234/ The laser system used in this work was focused operated in either the Q-fixed (free running) mode or to a spot size of 20 µm with sample sizes of the order of the Q-switched mode. Steel samples were ablated using 50 µm in diameter. Sixty-two glass specimens consisting the laser in the Q-fixed pulse mode. This setting works of 31 float glasses, 4 sheet glasses, and 27 container well for thermally conducting samples as the energy of glasses were analyzed. Steel samples were obtained from the laser radiation is absorbed by the surface, thereby 69 sources such as safes, firearm barrels, tools, angle iron, creating deep narrow craters. One to five shots were fired rods, and crowbars. on each site in quick succession rather than over a timed With respect to the glass samples, the authors’ argu- interval..234/ ment against dissolution noted the necessity of hydroflu- Nonconducting specimens, such as glass, were analyzed oric acid in order to digest the silicate matrix. Formation using the Q-switched pulse mode, whereby the laser of insoluble rare earth fluorides can greatly affect quanti- energy generates an ionizing plasma above the focal tation of these important fingerprint elements. Thus, the point on the sample. The authors further explain that digestion process can be quite lengthy in order to assure sampling is achieved in this mode as the laser-induced removal of excess hydrofluoric acid after the initial matrix plasma couples with the surface of the specimen and breakdown. cuts into it. Research demonstrated to the authors that According to these authors, the LA/ICPMS process analysis of the varying glass types in this study could be for complex forensic matrices is not yet completely achieved with a laser energy of 750 V at a rate of 15 Hz quantitative. However, it is still ideal for these types over a 60-s interval..234/ of specimens because virtually all forensic work is Results of this extensive study demonstrated that comparative, not absolute in its mission. The question reproducibility was readily achieved on a day-to-day basis. most often asked is: ‘‘Do the known and suspect samples Similarly, differentiation was possible on five colorless match?’’, rather than: ‘‘What is it?’’, or ‘‘How much is glass samples with relative refractive index differences there?’’ Thus, for the comparison of small, solid matrices, of less than 0.1%. Most promising for all aspects of lot LA/ICPMS is fast becoming the survey technique of production comparisons was the work that demonstrated choice. that brown glass bottles manufactured at the same plant In the described paper, sample preparation resembled on different days could also be distinguished on the that used for SEM or EDX work, in which the specimen basis of ternary plots of the replicate data. Results for (average size equal to 15 mm in diameter) was embedded replicate analyses of steel samples showed similar results. in a plastic block of 25 mm diameter and 10 mm thickness. Over time, the precision of the analytical technique The surface of the block was then polished to expose showed slight variations that in no way compared with the specimen. Alternatively, cyanoacrylate was used to the intersample variability demonstrated by repeated embed smaller samples onto the surface of the plastic sampling of five different specimens of the same type..234/ blocks..234/ The development of methodologies such as those The authors further explain that the laser signal demonstrated in this work would obviously require optimization was achieved for both sample types using expertise, time, and large specimen banks to begin the SRM 610 for Trace Elements in Glass (NIST, the evolution of a database for historical comparability. Gaithersburg, MD). This particular standard contains However, once the initial protocols were developed and a high concentration of the mid-mass rare earth element the software capabilities in place for data storage and lanthanum (139La), which makes it ideal for optimizing access, it is conceivable that training of less skilled both the laser and the ICPMS systems. Further, this or inexperienced technicians for routine use of this glass reference material was used as a standard for both technology would be easily achieved. That prospect specimens for its production of a clean steady state signal. makes the potential of LA/ICPMS highly promising for Continuous ablation with a metal standard could coat the routinely analyzed forensic specimens such as bullet lead, laser cell and contaminate the system over time. It should glass, steel, copper wire, soils, paints, polymers, and fibers. also be noted that concerns regarding the uniformity The description of each of the techniques mentioned of ablation of differing materials which could result in in this article is by no means complete. With regard to variation of the plasma load function is not at issue in this forensic applications, the methodologies are not routine work because of the comparative nature of the study. in some instances; nor has the need for further exploration Associations between samples of the same type will of useful methods been exhausted. There will continue to be based on their relative concentrations, not absolute be a need for better detection limits for smaller specimens quantitation of each specimen with respect to a standard with less alteration to the integrity of the evidence. As or reference material..234/ atomic spectrometric techniques become less intrusive Lastly, in the Apparatus section of the article by through the advent of sample introduction capabilities Watling et al.,.234/ it is stated that the laser can be such as laser ablation, the ability to justify the need

Coatings (Volume 2) Atomic Spectroscopy in Coatings Analysis ACKNOWLEDGMENTS Environment: Water and Waste (Volume 3) The authors wish to thank their colleagues in the Flame and Graphite Furnace Atomic Absorption Spec- Elemental Analysis Operations Group of the Materials trometry in Environmental Analysis ž Inductively Cou- Analysis Unit for their helpful comments and suggestions. pled Plasma Mass Spectrometry in Environmental Anal- Also, the staff of the Forensic Science Information and ysis Resource Center and the Automation Unit provided immense support, always in a friendly and timely manner. Environment: Water and Waste cont’d (Volume 4) Laser Ablation Inductively Coupled Plasma Spectrome- try in Environmental Analysis

ABBREVIATIONS AND ACRONYMS Forensic Science (Volume 5) Forensic Science: Introduction ž Scanning Electron AA Atomic Absorption Microscopy in Forensic Science CTD Charge Transfer Device DCP Direct Current Plasma Steel and Related Materials (Volume 10) EDL Electrodeless Discharge Lamp Steel and Related Materials: Introduction ž Atomic EDX Energy Dispersive X-ray Analysis Absorption and Emission Spectrometry, Solution-based GFAAS Graphite Furnace Atomic Absorption in Iron and Steel Analysis ž Metal Analysis, Sampling Spectroscopy and Sample Preparation in GHB g-Hydroxybutyrate GSR Gunshot Residue Atomic Spectroscopy (Volume 11) ICP Inductively Coupled Plasma Atomic Spectroscopy: Introduction ž Background Cor- ICPAES Inductively Coupled Plasma Atomic rection Methods in Atomic Absorption Spectroscopy ž Emission Spectrometry Graphite Furnace Atomic Absorption Spectrometry ž

Inductively Coupled Plasma/Optical Emission Spectrom- 11. S.S. Krishnan, ‘Firing Distance Determination by Ato- etry ž Laser Ablation in Atomic Spectroscopy ž Laser mic Absorption Spectrophotometry’, J. Forensic Sci., 18, Spectrometric Techniques in Analytical Atomic Spec- 351–356 (1973). trometry 12. G.D. Renshaw, C.A. Pounds, E.F. Pearson, ‘The Quan- titative Estimation of Lead, Antimony, and Barium Nuclear Methods (Volume 14) in Gunshot Residues by Non-flame Atomic Absorp- Elemental Analysis by Isotope Dilution ž Instrumental tion Spectrophotometry’, At. Absorpt. Newsl., 12,55–56 Neutron Activation Analysis (1973). 13. R.D. Cone, ‘Detection of Barium, Antimony, and Lead General Articles (Volume 15) in Gunshot Residue by Flameless Atomic Absorption Analytical Problem Solving: Selection of Analytical Spectrophotometry’, Police Weapons Center Bull., 6, 4–6 (1973). Methods ž Archaeological Chemical Analysis ž Liter- 14. J.A. Goleb, C.R. Midkiff, ‘Barium Contamination in ature Searching Methodology ž Microwave Techniques ž Gunshot Residue Collection Kits’, Appl. Spectrosc., 28, Quality Assurance in Analytical Chemistry ž Quantita- 382–383 (1974). tive Spectroscopic Calibration ž Traceability in Analytical 15. I.C. Stone, C.S. Petty, ‘Examination of Gunshot Resi- Chemistry dues’, J. Forensic Sci., 19, 784–788 (1974). 16. J.A. Goleb, C.R. Midkiff, ‘The Determination of Barium and Antimony in Gunshot Residue by Flameless Atomic REFERENCES Absorption Spectroscopy Using a Tantalum Strip Atom- izer’, Appl. Spectrosc., 29, 44–48 (1975). 1. F.S. Baechtel, ‘The Identification and Individualiza- 17. M.L. Newbury, ‘The Analysis of Gunshot Residue for tion of Semen Stains’, in Forensic Science Handbook, Antimony and Barium by Flameless Atomic Absorption ed. R. Saferstein, Prentice Hall, New Jersey, Vol. II, Spectrometry’, Can. Soc. Forensic Sci. J., 13, 19–26 1988. (1980). 2. B. Robertson, G. Vignaux (eds.), ‘Transfer Evidence’, in 18. J.T. Newton, ‘Rapid Determination of Antimony, Bar- Interpreting Evidence: Evaluating Forensic Evidence in ium, and Lead in Gunshot Residue Via Automated the Courtroom, Wiley, New York, 135–154, 1995. Atomic Absorption Spectrophotometry’, J. Forensic Sci., 3. V.P. Guinn, ‘Applications of Neutron Activation Analy- 26, 302–312 (1981). sis in Scientific Crime Detection’, GA-8013, Division of 19. L.C. Portis, R.K. Tilley, ‘A Filtration Technique for Technical Information, US Atomic Energy Commission, Gunshot Residue Analysis by SEM and/or FAAS’, 1967. Assoc. Firearms Toolmarks Examiners, 13, 93–99 (1981). 4. J.B. Weinstein, ‘Enhancing the Relationship of Science 20. S.S. Krishnan, K.A. Gillespie, E.J. Anderson, ‘Rapid and the Courts’, J. Forensic Sci., 43, 242–245 (1998). Detection of Firearm Discharge Residues by Atomic 5. P.M. Grant, K.J. Moody, I.D. Hutcheon, D.L. Phinney, Absorption and Neutron Activation Analysis’, J. Foren- J.S. Haas, A.M. Volpe, J.J. Oldani, R.E. Whipple, sic Sci., 16, 144–151 (1971). N. Stoyer, A. Alcaraz, J.E. Andrews, R.E. Russo, G.L. 21. W.D. Kinard, D.R. Lundy, ‘A Comparison of Neutron Klunder, B.D. Andersen, S. Cantlin, ‘Forensic Analyses Activation Analysis and Atomic Absorption Spec- of Suspect Illicit Nuclear Material’, J. Forensic Sci., 43, troscopy on Gunshot Residue’, ACS Symp. Ser., 13, 680–688 (1998). 97–107 (1975). 6. R.C. McFarland, M.E. McLain, ‘Rapid Neutron Activa- 22. R.D. Beaty, J.D. Kerber, ‘Concepts, Instrumentation, tion Analysis for Gunshot Residue Determination’, J. and Techniques’, in Atomic Absorption Spectrophotom- Forensic Sci., 18, 226–231 (1973). etry, The Perkin-Elmer Corporation, Norwalk, 1993. 7. K.K. Pillay, W.A. Jester, H.A. Fox, ‘New Method for the 23. C.B. Boss, K.J. Fredeen, ‘Concepts, Instrumentation, Collection and Analysis of Gunshot Residues as Forensic and Techniques’, in Inductively Coupled Plasma Optical Evidence’, J. Forensic Sci., 19, 768–783 (1974). Emission Spectrometry, The Perkin-Elmer Corporation, 8. S. Felby, ‘Determination of Organosilicon Oxide Poly- Norwalk, 1997. mers in Tissue by Atomic Absorption Spectroscopy 24. A. Montaser, Inductively Coupled Plasma Mass Spec- Using HGA Graphite Furnace, Forensic Sci. Int., 32, trometry, Wiley-VCH, New York, 1998. 61–65 (1986). 25. J.D. Kerber, ‘The HGA Graphite Furnace Increases the 9. E.C. Blacklock, P.A. Sadler, ‘A Rapid Screening Method Scope of Atomic Absorption Spectroscopy’, Instrum. for Heavy Metals in Biological Materials by Emission News, 24, 2–4 (1974). Spectroscopy’, Clin. Chim. Acta, 113, 87–94 (1981). 26. J. Chen, H. Berndt, G. Tolg, ‘A Contribution to the 10. A.L. Green, J.P. Sauve, ‘The Analysis of Gunshot Trace Analysis of High-purity Iron by Atomic Spectrom- Residue by Atomic Absorption Spectrophotometry’, At. etry (Flame-AAS, Furnace-AAS, ICP/OES)’, Fresenius’ Absorpt. Newsl., 11, 93–95 (1972). J. Anal. Chem., 344, 526–534 (1992).

27. T.J. Gluodenis, Jr, J.F. Tyson, ‘Flow Injection Systems 45. ‘Atomic Spectrometry Updated References’, J. Anal. At. for Directly Coupling On-line Digestions with Analytical Spectrom., 9, 135R–146R (1994). Atomic Spectrometry. Part 1: Dissolution of Cocoa 46. R.C. Carpenter, ‘The Analysis of Some Evidential under Stopped-ﬂow, High-pressure Conditions’, J. Anal. Materials by Inductively Coupled Plasma Optical Emis- At. Spectrom., 7, 301–306 (1992). sion Spectrometry’, Forensic Sci. Int., 27, 157–163 28. M.S. Cresser, ‘Atomic Spectrometry in Environmental (1985). Analysis: Jam Today or Jam Tomorrow?’, J. Anal. At. 47. R. Koons, ‘ICP Atomic Spectrometry in the Forensic Spectrom., 8, 269–272 (1993). Laboratory’, Spectroscopy, 8, 16–21 (1993). 29. D.J. Halls, ‘Analytical Minimalism Applied to the Deter- 48. M. Lalchev, I. Ionov, N. Daskalova, ‘Application of mination of Trace Elements by Atomic Spectrometry’, Inductively Coupled Plasma Atomic Emission Spec- J. Anal. At. Spectrom., 10, 169–175 (1995). trometry in Forensic Science’, J. Anal. At. Spectrom., 30. H. van der Jagt, P.J. Stuyfzand, ‘Methods for Trace Ele- 12, 21–24 (1997). ment Analysis in Surface Water, Atomic Spectrometry 49. J.B. Dawson, R.D. Snook, W.J. Price, ‘Background and in Particular’, Fresenius’ J. Anal. Chem., 354, 32–40 Background Correction in Analytical Atomic Spectrom- (1996). etry Part 1: Emission Spectrometry. A Tutorial Review’, 31. M.E. Moreno, C. Perez-Conde, C. Camara, ‘Sensitiza- J. Anal. At. Spectrom., 8, 517–537 (1993). tion of Stibine Generation: Antimony Determination in 50. B.L. Sharp, S. Chenery, R. Jowitt, S.T. Sparkes, Environmental Samples by Atomic Fluorescence Spec- A. Fisher, ‘Atomic Spectrometry Update – Atomic trometry’, J. Anal. At. Spectrom., 13, 1181–1187 (1998). Emission Spectrometry’, J. Anal. At. Spectrom., 9, 32. E. Ivanova, W. Van Mol, F. Adams, ‘Electrothermal 171R–188R (1994). Atomic Absorption Spectrometric Determination of 51. J. Marshall, A. Fisher, S. Chenery, S.T. Sparkes, ‘Atomic Cadmium and Lead in Blood Using Flow Injection On- Spectrometry Update – Atomic Emission Spectrome- line Sorption Preconcentration in a Knotted Reactor’, try’, J. Anal. At. Spectrom., 11, 213R–238R (1996). Spectrochim. Acta, Part B, 53, 1041–1048 (1998). 52. J. Marshall, E.H. Evans, A. Fisher, S. Chenery, ‘Atomic 33. G. Norheim, P.E. Paus, ‘Arsenic Determination in Spectrometry Update – Atomic Emission Spectrome- Autopsy Material Using Atomic Absorption Spec- try’, J. Anal. At. Spectrom., 12, 263R–290R (1997). troscopy’, Z. Rechtsmed., 75, 127–130 (1974). 53. K.W. Jackson, S. Lu, ‘Atomic Absorption, Atomic Emis- 34. S.P. Singhal, ‘Atomic Absorption Spectroscopy in Foren- sion, and Flame Emission Spectrometry’, Anal. Chem., sic Chemistry’, J. Can. Soc. Forensic Sci., 7, 7–17 (1974). 70, 363R–383R (1998). 35. G.W. Walker, ‘Atomic Absorption Spectroscopy’, 54. S.J. Hill, J.B. Dawson, W.J. Price, I.L. Shuttler, C.M.M. Chem. Br., 11, 440–441 (1975). Smith, J.F. Tyson, ‘Atomic Spectrometry Update – 36. M. Ravreby, ‘Analysis of Long-range Bullet Entrance Advances in Atomic Absorption and Fluorescence Holes by Atomic Absorption Spectrophotometry and Spectrometry and Related Techniques’, J. Anal. At. Scanning Electron Microscopy’, Israel J. Forensic Sci., Spectrom., 12, 327R–379R (1997). 27, 92–112 (1982). 55. J.R. Bacon, J.S. Crain, A.W. McMahon, J.G. Williams, 37. W. Slavin, ‘A Comparison of Atomic Spectroscopic ‘Atomic Spectrometry Update – Atomic Mass Spec- Analytical Techniques’, Spectroscopy, 6, 16–21 (1991). trometry’, J. Anal. At. Spectrom., 12, 407R–448R 38. D.M. Grant (ed.), ‘Gunshot Residue Testing Laborato- (1997). ries in the United States, Unpublished List’, revised by 56. J.R. Bacon, J.S. Crain, L. Van Vaeck, J.G. Williams, the FBI Laboratory, June, 1998. ‘Atomic Spectrometry Update – Atomic Mass Spec- 39. C.A. Peters, Forensic Examiner, personal communica- trometry’, J. Anal. At. Spectrom., 13, 171R–208R (1998). tion, 1998. 57. A. Taylor, S. Branch, H.M. Crews, D.J. Halls, M. White, 40. W. Slavin, ‘Atomic Absorption Spectroscopy: Why Has ‘Atomic Spectrometry Update – Clinical and Biological It Become Successful?’, Anal. Chem., 63, 1033A–1038A Materials, Food and Beverages’, J. Anal. At. Spectrom., (1991). 9, 87R–134R (1994). 41. R. Knight, S.J. Haswell, S.W. Lindow, J. Batty, ‘Determ- 58. A. Taylor, S. Branch, H.M. Crews, D.J. Halls, M. White, ination of Mercury in Hair by Coupled CVAA/ICPMS’, ‘Atomic Spectrometry Update – Clinical and Biological J. Anal. At. Spectrom., 14, 127–129 (1999). Materials, Food and Beverages’, J. Anal. At. Spectrom., 42. J.H. Sherﬁnski, ‘A Graphite Tube Degradation Study 10, 61R–112R (1995). of Barium at Gunshot Residue Levels’, Atom. Abs. 59. A. Taylor, S. Branch, H.M. Crews, D.J. Halls, L.M.W. Newsletter, 14, 26–28 (1975). Owen, M. White, ‘Atomic Spectrometry Update – 43. H.C. Harrison, R. Gilroy, ‘Firearms Discharge Residue’, Clinical and Biological Materials, Food and Beverages’, J. Forensic Sci., 4, 184–199 (1959). J. Anal. At. Spectrom., 12, 119R–221R (1997). 44. T.A. Brettell, R. Saferstein, ‘Forensic Science’, Anal. 60. A. Taylor, S. Branch, D.J. Halls, L.M.W. Owen, Chem., 69, 123R–143R (1997). M. White, ‘Atomic Spectrometry Update – Clinical and

Biological Materials, Food and Beverages’, J. Anal. At. 75. I. Karadjova, G. Zachariadis, G. Boskou, J. Stratis, Elec- Spectrom., 13, 57R–106R (1998). trothermal Atomic Absorption Spectrometric Determi- 61. M.S. Cresser, J. Armstrong, J. Cook, J.R. Dean, P. Wat- nation of Aluminum, Cadmium, Chromium, Copper, kins, M. Cave, ‘Atomic Spectrometry Update – Iron, Manganese, Nickel, and Lead in Olive Oil’, J. Environmental Analysis’, J. Anal. At. Spectrom., 8, Anal. At. Spectrom., 13, 201–204 (1998). 1R–78R (1993). 76. F. Dolinsek, J. Stupar, V. Vrscaj, ‘Direct Determination 62. J.R. Dean, L.M. Garden, J. Armstrong, M.S. Cresser, of Cadmium and Lead in Geological and Plant Materials M. Cave, P. Watkins, ‘Atomic Spectrometry Update – by Electrothermal Atomic Absorption Spectrometry’, J. Environmental Analysis’, J. Anal. At. Spectrom., 12, Anal. At. Spectrom., 6, 653–660 (1991). 19R–87R (1997). 77. T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe, 63. J.R. Dean, O. Butler, A. Fisher, L.M. Garden, M.S. T. Tominaga, ‘Determination of Lanthanides and Other Cresser, P. Watkins, M. Cave, ‘Atomic Spectrometry Trace Elements in Ferns by Instrumental Neutron Update – Environmental Analysis’, J. Anal. At. Spec- Activation Analysis’, J. Radioanal. Nucl. Chem., 217, trom., 13, 1R–56R (1998). 117–124 (1997). 64. R.E. Sturgeon, ‘Future of Atomic Spectrometry for 78. H. Zhou, J. Liu, ‘The Determination of Rare Earth Environmental Analysis’, J. Anal. At. Spectrom., 13, Elements in Plant Foods by ICPMS’, At. Spectrosc., 351–361 (1998). 18, 192–194 (1997). 65. J. Marshall, J. Carroll, J.S. Crighton, ‘Atomic Spectrom- 79. J.D. Greenough, H.P. Longerich, S.E. Jackson, ‘Ele- etry Update – Industrial Analysis: Metals, Chemicals, ment Fingerprinting of Okanagan Valley Wines Using and Advanced Materials’, J. Anal. At. Spectrom., 6, ICPMS: Relationships Between Wine Composition, 283R–339R (1991). Vineyard, and Wine Color’, Aust. J. Grape Wine Res., 3, 66. J. Marshall, J. Carroll, J.S. Crighton, C.L.R. Barnard, 75–83 (1997). 80. M.Y. Perez-Jordan, J. Soldevila, A. Salvador, A. Pastor, ‘Atomic Spectrometry Update – Industrial Analysis: M. de la Guardia, ‘Inductively Coupled Plasma Mass Metals, Chemicals, and Advanced Materials’, J. Anal. Spectrometry Analysis of Wines’, J. Anal. At. Spectrom., At. Spectrom., 7, 349R–411R (1992). 13, 33–39 (1998). 67. J. Marshall, J. Carroll, J.S. Crighton, C.L.R. Barnard, 81. M. Segura, Y. Madrid, C. Camara, ‘Evaluation of Ato- ‘Atomic Spectrometry Update – Industrial Analysis: mic Fluorescence and Atomic Absorption Spectrometric Metals, Chemicals, and Advanced Materials’, J. Anal. Techniques for the Determination of Arsenic in Wine At. Spectrom., 9, 319R–356R (1994). and Beer by Direct Hydride Generation Sample Intro- 68. J.S. Crighton, J. Carroll, B. Fairman, J. Haines, M. duction’, J. Anal. At. Spectrom., 14, 131–135 (1999). Hinds, ‘Atomic Spectrometry Update – Industrial Anal- 82. J.A. Nobrega, Y. Gelinas, A. Krushevska, R.A. Barnes, ysis: Metals, Chemicals, and Advanced Materials’, J. ‘Direct Determination of Major and Trace Elements in Anal. At. Spectrom., 11, 461R–508R (1996). Milk by Inductively Coupled Plasma Atomic Emission 69. J.S. Crighton, B. Fairman, J. Haines, M. Hinds, S.M. and Mass Spectrometry’, J. Anal. At. Spectrom., 12, Nelms, D.M. Penny, ‘Atomic Spectrometry Update – 1243–1246 (1997). Industrial Analysis: Metals, Chemicals, and Advanced 83. C. Barbante, T. Bellomi, G. Mezzadri, P. Cescon, Materials’, J. Anal. At. Spectrom., 12, 509R–542R (1997). G. Scarponi, C. Morel, S. Jay, K. Van de Velde, C. Fe- 70. A.M. Paudyn, R.G. Smith, ‘Determination of Elements rrari, C.F. Boutron, ‘Direct Determination of Heavy in Paints and Paint Scrapings by Inductively Cou- Metals at Picogram per Gram Levels in Greenland and pled Plasma Atomic Emission Spectrometry Using Antarctic Snow by Double Focusing Inductively Cou- Microwave Assisted Digestion’, Fresenius’ J. Anal. pled Plasma Mass Spectrometry’, J. Anal. At. Spectrom., Chem., 345, 695–700 (1993). 12, 925–931 (1997). 71. J. Zieba-Palus, ‘Examination of Used Motor Oils by 84. G. Yaprak, B. Uysal, ‘Determination of Low Level 210Pb Flame AAS for Criminalistic Purposes: A Diagnostic in Tobacco’, J. Radioanal. Nucl. Chem., 229, 153–155 Study’, Forensic Sci. Int., 91, 171–179 (1998). (1998). 72. M.A. Ryan, ‘Finding Food Imposters: It’s Not Just 85. R.Y.P. Bhatia, M. Prabhakar, T.S. Rao, K. Raghunath, Peanuts’, Today’s Chemist at Work, 7, 63–66 (1998). ‘Determination of Chromium, Cobalt, Copper, and 73. G. Gugliotta, ‘High-tech Trade Enforcement Tracks Zinc Contents in Tobacco Ash of Different Cultivars Peanuts Across Borders’, Washington Post, Federal Page of Tobacco by Inductively Coupled Plasma Atomic (4 December, 1997). Emission Spectrometry’, Indian J. Forensic Sci., 2, 74. R. Schwartz, ‘ICPMS Determination of Trace Element 145–156 (1988). Composition of Agricultural Products for Geographic 86. M.O.A. Oladipo, O.O. Ajayi, S.B. Elegba, S.O. Alonge, Origin Determination’, 1998 Winter Conference on S.A. Adeleye, ‘The Determination of Minor and Trace Plasma Spectrometry, Scottsdale, AZ, 5–10 January, Elements in Some Nigerian Cigarettes and Raw Tobacco Poster FP01, 1998. Using Inductively Coupled Plasma Mass Spectrometry

(ICPMS)’, J. Environ. Sci. Health A, 28, 839–857 100. N.K. Mottet, R.L. Body, ‘Mercury Burden of Human (1993). Autopsy Organs and Tissues’, Arch. Environ. Health, 29, 87. C. Roux, ‘The Analysis of Inorganic Additives in 18–24 (1974). Polyester Fibers by Inductively Coupled Plasma Atomic 101. M.W. Hinds, ‘Determination of Mercury in Gold Bullion Emission Spectroscopy’, in Proc. Meet. Int. Assoc. by Flame and Graphite Furnace Atomic Absorption Forensic Sci., 216–224, Vol. 4, 1995. Spectrometry’, Spectrochim. Acta, Part B, 53, 1063–1068 88. J.R. Vogt, D.M. Hashii, ‘Trace Element Distributions (1998). in Man-made Fibers’, J. Radioanal. Nucl. Chem., 15, 102. Z. De-Qiang, N. Zhe-Ming, S. Han-Wen, ‘Stabilization 355–366 (1973). of Organic and Inorganic Mercury in the Graphite 89. S. Suzuki, H. Tsuchihashi, K. Nakajima, A. Matsushita, Furnace with (NH4)2PdCl6-(NH4)3 RhCl6 as a Mixed T. Nagao, ‘Analyses of Impurities in Methamphetamine Chemical Modiﬁer’, Spectrochim. Acta, Part B, 53, by Inductively Coupled Plasma Mass Spectrometry and 1049–1055 (1998). Ion Chromatography’, J. Chromatogr., 437, 322–327 103. P. Canada Rudner, J.M. Cano Pavon, F. Sanchez Rojas, (1988). A. Garcia de Torres, ‘Use of Flow Injection Cold Vapor 90. T. Kishi, ‘Analysis of Trace Elements in Metham- Generation and Preconcentration on Silica Functional- phetamine Hydrochloride by Inductively Coupled ized with Methylthiosalicylate for the Determination of Plasma Mass Spectrometry’, J. Res. Natl. Bur. Stand., Mercury in Biological Samples and Seawater by Induc- 93, 469–471 (1988). tively Coupled Plasma Atomic Emission Spectrometry’, 91. K.A. Wolnik, D.T. Heitkemper, J.B. Crowe, B.S. Barnes, J. Anal. At. Spectrom., 13, 1167–1171 (1998). T.W. Brueggemeyer, ‘Application of Inductively Cou- 104. G.R. Boaventura, A.C. Barbosa, G.A. East, ‘Multivessel System for Cold-vapor Mercury Generation: Determi- pled Plasma Atomic Emission and Mass Spectrometry to nation of Mercury in Hair and Fish’, Biol. Trace Elem. Forensic Analysis of Sodium Gamma Hydroxy Butyrate Res., 60, 153–161 (1997). and Ephedrine Hydrochloride’, J. Anal. At. Spectrom., 105. J.A. Moreton, H.T. Delves, ‘Simple Direct Method for 10, 177–181 (1995). the Determination of Total Mercury Levels in Blood 92. R.J. Wells, S.V. Skopec, R. Iavetz, J. Robertson, ‘Trace and Urine and Nitric Acid Digests of Fish by Inductively Element Analysis of Heroin by ICPMS’, Chem. Aus- Coupled Plasma Mass Spectrometry’, J. Anal. At. tralia, 62, 14–25 (1995). Spectrom., 13, 659–665 (1998). 93. P. Bermejo-Barrera, A. Moreda-Pineiro, J. Moreda- 106. J. Yoshinaga, N. Matsuo, H. Imai, M. Nakazawa, T. Su- Pineiro, A. Bermejo-Barrera, ‘Application of Rapid zuki, ‘Application of Inductively Coupled Plasma Mass Electrothermal Atomic Absorption Spectrometric Meth- Spectrometry (ICPMS) to Multi-element Analysis of ods to the Determination of Ag, Al, Cd, and Mn in Human Organs’, Int. J. Environ. Anal. Chem., 41,27–38 Cocaine and Heroin Samples’, Fresenius’ J. Anal. Chem., (1990). 358, 844–847 (1997). 107. T.D.B. Lyon, G.S. Fell, K. McKay, R.D. Scott, ‘Accu- 94. R.J. Watling, ‘Sourcing the Provenance of Cannabis racy of Multi-element Analysis of Human Tissue Obtai- Crops Using Inter-element Association Patterns ‘‘Fin- ned at Autopsy Using Inductively Coupled Plasma Mass gerprinting’’ and Laser Ablation ICPMS’, 1998 Winter Spectrometry’, J. Anal. At. Spectrom., 6, 559–564 (1991). Conference on Plasma Spectrometry, Scottsdale, AZ, 108. S.F. Durant, ‘Inductively Coupled Plasma Mass Spec- 5–10 January, W2, 1998. trometry for Biological Analysis’, Trends Anal. Chem., 95. R.J. Watling, ‘Sourcing the Provenance of Cannabis 11, 68–73 (1992). Crops Using Inter-element Association Patterns ‘‘Fin- 109. T. Tanaka, K. Hara, A. Tanimoto, K. Kasai, T. Kira, gerprinting’’ and Laser Ablation ICPMS’, J. Anal. At. N. Tanaka, T. Takayasu, ‘Determination of Arsenic in Spectrom., 13, 917–926 (1998). Blood and Stomach Contents by Inductively Coupled 96. H. Al-Shahristani, I.K. Al-Haddad, ‘Mercury Content of Plasma/Mass Spectrometry (ICP/MS)’, Forensic Sci. Int., Hair from Normal and Poisoned Persons’, J. Radioanal. 81, 43–50 (1996). Nucl. Chem., 15, 59–70 (1973). 110. L. Moens, ‘Applications of Mass Spectrometry in the 97. E.O. Espinoza, M. Mann, B. Bleasdell, S. DeKorte, Trace Element Analysis of Biological Materials’, Frese- M. Cox, ‘Toxic Metals in Selected Traditional Chinese nius’ J. Anal. Chem., 359, 309–316 (1997). Medicinals’, J. Forensic Sci., 41, 453–456 (1996). 111. C.J. Amarasiriwardena, N. Lupoli, V. Potula, S. Korrick, 98. M. Piette, B. Desmet, R. Dams, ‘Determination of H. Hu, ‘Determination of the Total Arsenic Concentra- Strontium in Human Whole Blood by ICPAES’, Sci. tion in Human Urine by Inductively Coupled Plasma Total Environ., 141, 269–273 (1994). Mass Spectrometry: A Comparison of the Accuracy 99. P. Capota, M. Ropota, M. Constantin, V. Stoenescu, of Three Analytical Methods’, Analyst, 123, 441–445 ‘Determination of Microelements in Human Teeth (1998). Using the ICPAES Method’, Chem. Anal., 42, 721–724 112. C. Latkoczy, T. Prohaska, G. Stingeder, M. Teschler- (1997). Nicola, ‘Strontium Isotope Ratio Measurements in

Prehistoric Human Bone Samples by Means of High- 124. M.C. Webb, D.C. Paschal, W.C. Elliott, H.P. Hopkins, resolution Inductively Coupled Plasma Mass Spectrom- A.M. Ghazi, B.C. Ting, I. Romieu, ‘ICPMS Determina- etry (HR/ICPMS)’, J. Anal. At. Spectrom., 13, 561–566 tion of Lead Isotope Ratios in Whole Blood, Pottery, (1998). and Leaded Gasoline: Lead Sources in Mexico City’, At. 113. S. Granero, J.M. Llobet, M. Schuhmacher, J. Corbella, Spectrosc., 19, 156–163 (1998). J.L. Domingo, ‘Biological Monitoring of Environmental 125. T.Y. Toribara, A.G. Muhs, ‘Hair: A Keeper of History’, Pollution and Human Exposure to Metals in Tarragona, Arctic Anthropol., 21, 99–108 (1984). Spain. Part I. Levels in Hair of School Children’, Toxic 126. K. Bencze, ‘What Contribution Can Be Made to Biolog- Elem. Electrol., 15, 39–43 (1998). ical Monitoring by Hair Analysis? Part 1’, Fresenius’ J. 114. J. Zheng, W. Goessler, A. Geiszinger, W. Kosmus, Anal. Chem., 337, 867–876 (1990). B. Chen, G. Zhuang, K. Xu, G. Sui, ‘Multi-element 127. K. Bencze, ‘What Contribution Can Be Made to Biolog- Determination in Earthworms with Instrumental Neu- ical Monitoring by Hair Analysis? Part 2’, Fresenius’ J. tron Activation Analysis and Inductively Coupled Anal. Chem., 338, 58–61 (1990). Plasma Mass Spectrometry: A Comparison’, J. Radio- 128. V. Valkovic, Human Hair, Trace-element Levels,CRC anal. Nucl. Chem., 223, 149–155 (1997). Press, Boca Raton, Vol. II, 1988. 115. B.S. Sheppard, J.A. Caruso, D.T. Heitkemper, K.A. 129. G.C. Verghese, R. Kishore, V.P. Guinn, ‘Differences in Wolnik, ‘Arsenic Speciation by Ion Chromatography Trace-element Concentrations in Hair Between Males with Inductively Coupled Plasma Mass Spectrometric and Females’, J. Radioanal. Chem., 15, 329–335 (1973). Detection’, Analyst, 117, 971–975 (1992). 130. V.P. Guinn, M. Gavrilas-Guinn, R. Demiralp, ‘Measure- 116. I.B.-A. Razagui, S.J. Haswell, ‘The Determination of ment of Arsenic in Sectioned Hair Samples by Instru- Mercury and Selenium in Maternal and Neonatal mental Neutron Activation Analysis’, J. Radioanal. Nucl. Scalp Hair by Inductively Coupled Plasma Mass Chem., 179, 365–368 (1994). Spectrometry’, J. Anal. Toxicol., 21, 149–153 (1997). 131. V.P. Guinn, R. Demiralp, ‘Arsenic in Hair by INAA – A 117. J. Yoshinaga, M. Morita, ‘Determination of Mercury in Major Recent Murder Case’, J. Radioanal. Nucl. Chem., Biological and Environmental Samples by Inductively 168, 249–256 (1993). Coupled Plasma Mass Spectrometry with the Isotope 132. A. Pazirandeh, A.H. Brati, M. Ghannadi Marageh, Dilution Technique’, J. Anal. At. Spectrom., 12, 417–420 ‘Determination of Arsenic in Hair Using Neutron Acti- (1997). vation’, Appl. Radiat. Isot., 49, 753–759 (1998). 118. H.P. Chen, D.C. Paschal, D.T. Miller, J.C. Morrow, 133. M. Saiki, M.B.A. Vasconcellos, L.J. de Arauz, R. Ful- ‘Determination of Total and Inorganic Mercury in Whole faro, ‘Determination of Trace Elements in Human Head Blood by On-line Digestion with Flow Injection’, At. Hair by Neutron Activation Analysis’, J. Radioanal. Spectrosc., 19, 176–179 (1998). Nucl. Chem., 236, 25–28 (1998). 119. S. Saverwyns, X. Zhang, F. Vanhaecke, R. Cornelis, 134. S.Y. Cho, S.G. Jang, Y.S. Chung, ‘Human Hair Identiﬁ- L. Moens, R. Dams, ‘Speciation of Six Arsenic Com- cation by Instrumental Neutron Activation Analysis’, J. pounds Using High Performance Liquid Chromatog- Radioanal. Nucl. Chem., 229, 143–147 (1998). raphy/Inductively Coupled Plasma Mass Spectrometry 135. H. Hagedorn-Gotz, G. Kuppers, M. Stoeppler, ‘On Ni- with Sample Introduction by Thermospray Nebuliza- ckel Contents in Urine and Hair in a Case of Exposure tion’, J. Anal. At. Spectrom., 12, 1047–1052 (1997). to Nickel Carbonyl’, Arch. Toxicol., 38, 275–285 (1977). 120. N. Miekeley, M.O. Amato, ‘Fast Hg Determination in 136. F. Diaz-Barriga, M.A. Santos, J. de Jesus Mejia, Biological Samples by ICPMS Using Minitube Furnace L. Batres, L. Yanez, L. Carrizales, E. Vera, L.M. del Catalytic Combustion’, At. Spectrosc., 18, 186–192 Razo, M.E. Cebrian, ‘Arsenic and Cadmium Expo- (1997). sure in Children Living Near a Smelter Complex in 121. J. Lintschinger, P. Schramel, A. Hatalak-Rauscher, San Luis Potosi, Mexico’, Environ. Res., 62, 242–250 I. Wendler, B. Michalke, ‘A New Method for the Analy- (1993). sis of Arsenic Species in Urine by Using HPLC/ICPMS’, 137. M. Keynes, ‘Did Napoleon Die from Arsenical Poison- Fresenius’ J. Anal. Chem., 362, 313–318 (1998). ing?’, Lancet, 344, 276 (1994). 122. D. Karunasagar, J. Arunachalam, S. Gangadharan, 138. C.T. Wang, W.T. Chang, C.W. Huang, S.S. Chou, C.T. ‘Development of a ‘‘Collect and Punch’’ Cold Vapor Lin, S.J. Liau, R.T. Wang, ‘Studies on the Concentra- Inductively Coupled Plasma Mass Spectrometric Method tions of Arsenic, Selenium, Copper, Zinc, and Iron in the for the Direct Determination of Mercury at Nanograms Hair of Blackfoot Disease Patients in Different Clinical per Liter Levels’, J. Anal. At. Spectrom., 13, 679–682 Stages’, Eur. J. Clin. Chem. Clin. Biochem., 32, 107–111 (1998). (1994). 123. K. Lee, S. Jiang, H. Liu, ‘Determination of Mercury in 139. W. Ashraf, M. Jaffar, D. Mohammad, ‘Trace Metal Con- Urine by Electrothermal Vaporization Isotope Dilution tamination Study of Scalp Hair of Occupationally Inductively Coupled Plasma Mass Spectrometry’, J. Exposed Workers’, Bull. Environ. Contam. Toxicol., 53, Anal. At. Spectrom., 13, 1227–1231 (1998). 516–523 (1994).

140. W. Ashraf, M. Jaffar, D. Mohammad, ‘Levels of Selected Application in Firearm Investigations’, J. Forensic Sci., Trace Metals in Hair of Urban and Rural Adult Male 38, 1161–1171 (1993). Population of Pakistan’, Bull. Environ. Contam. Toxicol., 156. C.R. Midkiff, ‘SIRA – A New Forensic Tool, Part I: 54, 207–213 (1995). Bullet Lead Examinations’, Mid Atlant. Assoc. Forensic 141. A. de Peyster, J.A. Silvers, ‘Arsenic Levels in Hair of Sci. Newsl., 26(3), 9–11 (1998). Workers in a Semiconductor Fabrication Facility’, Am. 157. C.R. Midkiff, ‘SIRA – A New Forensic Tool, Part II: Ind. Hyg. Assoc. J., 56, 377–383 (1995). Bullet Lead and More’, Mid Atlant. Assoc. Forensic Sci. 142. V. Bencko, ‘Use of Human Hair as a Biomaker in the Newsl., 26(4), 7–9 (1998). Assessment of Exposure to Pollutants in Occupational 158. D.G. Havekost, Report of the Visits of SA Donald G. and Environmental Settings’, Toxicology, 101, 29–39 Havekost and Dr Max A. Haney to Winchester-Western (1995). and Smith and Wesson Ammunition Plants, East Alton, 143. M.A. Armienta, R. Rodriguez, O. Cruz, ‘Arsenic Con- and Alton, Illinois, unpublished report, 1974. tent in Hair of People Exposed to Natural Arsenic 159. Y. Suzuki, Y. Marumo, ‘Determination of Trace Impu- Polluted Groundwater at Zimapan, Mexico’, Bull. Envi- rities in Lead Shotgun Pellets by ICPMS’, Anal. Sci., 12, ron. Contam. Toxicol., 59, 583–589 (1997). 129–132 (1996). 144. T. Lin, Y. Huang, M. Wang, ‘Arsenic Species in Drinking 160. T. Dufosse, P. Touron, ‘Comparison of Bullet Alloys by Water, Hair, Fingernails, and Urine of Patients with Chemical Analysis: Use of the ICPMS Method’, Forensic Blackfoot Disease’, J. Toxicol Environ. Health, A, 53, Sci. Int., 91, 197–206 (1998). 85–93 (1998). 161. R.O. Keto, ‘Analysis and Comparison of Bullet Leads 145. J. Buchancova, G. Klimentova, M. Knizkova, D. Mesko, by Inductively Coupled Plasma Mass Spectrometry’, J. E. Galikova, J. Kubik, E. Fabianova, M. Jakubis, ‘Health Forensic Sci., 44, 1020–1026 (1999). Status of Workers of a Thermal Power Station Exposed 162. C.A. Peters, D.G. Havekost, R.D. Koons, ‘Multiele- for Prolonged Periods to Arsenic and Other Elements ment Analysis of Bullet Lead by Inductively Coupled from Fuel’, Centr. Eur. J. Publ. Health, 6, 29–36 Plasma/Atomic Emission Spectrometry’, Crime Lab. (1998). Dig., 15, 33–38 (1988). 146. R.D. Koons, C.A. Peters, ‘Axial Distribution of 163. Unpublished Database of Compositional Bullet Lead Arsenic in Individual Human Hairs by Solid Sampling Analyses by the Elemental Analysis Operations Group, Graphite Furnace AAS’, J. Anal. Toxicol., 18, 36–40 Materials and Devices Unit, Scientific Analysis Section, (1994). FBI Laboratory, Washington, DC, 1999. 147. W. Galas, J. Trzcionka, ‘ICPAES Method in the Deter- 164. R.S. Maloney, J.I. Thornton, Color Tests for Dipheny- mination of the Metals in Human Hair’, Chem. Anal., lamine Stabilizer and Related Compounds in Smokeless 42, 697–702 (1997). Gunpowder, 3rd Annual Meeting of the American 148. M. Wolfsperger, G. Hauser, W. Gossler, C. Schlagen- Academy of Forensic Science, Los Angeles, CA, haufen, ‘Heavy Metals in Human Hair Samples from Austria and Italy: Influence of Sex and Smoking Habits’, 1981. Sci. Tot. Environ., 156, 235–242 (1994). 165. H. Meng, B. Caddy, ‘Gunshot Residue Analysis – A 149. J. Yoshinaga, Y. Shibata, M. Morita, ‘Trace Elements Review’, J. Forensic Sci., 42, 553–570 (1997). Determined Along Single Strands of Hair by Inductively 166. R.D. Koons, ‘Analysis of Gunshot Primer Residue Coupled Plasma Mass Spectrometry’, Clin. Chem., 39, Collection Swabs by Inductively Coupled Plasma/Mass 1650–1655 (1993). Spectrometry’, J. Forensic Sci., 43, 748–754 (1998). 150. G. Wallace, personal communication, 1999. 167. M.H. Mach, A. Pallos, P.F. Jones, ‘Feasibility of Gun- 151. G.W. Stupian, ‘Lead Isotope Ratio Measurements: A shot Residue Detection Via Its Organic Constituents. Potential Method for Bullet Identification’, J. Forensic Part I: Analysis of Smokeless Powders by Combined Sci. Soc., 15, 161–164 (1975). Gas Chromatography/Chemical Ionization Mass Spec- 152. R.M. Farquhar, J.A. Walthall, R.G.V. Hancock, ‘18th trometry’, J. Forensic Sci., 23, 433–445 (1978). Century Lead Smelting in Central North America: 168. D.B. Dahl, P.F. Lott, ‘Gunshot Residue Determination Evidence from Lead Isotope and INAA Measurements’, by Means of Gunpowder Stabilizers Using High- J. Arch. Sci., 22, 639–648 (1995). performance Liquid Chromatography with Electro- 153. B. Keisch, R.C. Callahan, ‘Lead Isotope Ratios in chemical Detection and Analysis of Metallic Residues Artists’ Lead White: A Progress Report’, Archaeometry, by Graphite Furnace Atomic Absorption Spectropho- 18, 181–193 (1976). tometry’, Microchem. J., 35, 347–359 (1987). 154. M.A. Haney, J.F. Gallagher, ‘Elemental Analysis of 169. G. Hellmiss, W. Lichtenberg, M. Weiss, ‘Investigation Bullet Lead by Spark Source Mass Spectrometry’, Anal. of Gunshot Residues by Means of Auger Electron Chem., 47, 62–65 (1975). Spectroscopy’, J. Forensic Sci., 32, 747–760 (1987). 155. J. Andrasko, I. Kopp, A. Abrink, T. Skiold, ‘Lead Iso- 170. R.S. White, A.D. Owens, ‘Automation of Gunshot tope Ratios in Lead Smears and Bullet Fragments and Residue Detection and Analysis by Scanning Electron

Microscopy/Energy Dispersive X-ray Analysis (SEM/EDX)’, with Simultaneous Determination of Major and Trace J. Forensic Sci., 32, 1595–1603 (1987). Elements by ICP/OES’, Talanta, 40, 1207–1211 (1993). 171. R.D. Koons, D.G. Havekost, C.A. Peters, ‘Determina- 185. D.G. Poolman, P.C. Pistorius, ‘The Possibility of Using tion of Barium in Gunshot Residue Collection Swabs Elemental Analysis to Identify Debris from the Cut- Using Inductively Coupled Plasma/Atomic Emission ting of Mild Steel’, J. Forensic. Sci., 41, 998–1004 Spectrometry’, J. Forensic Sci., 33, 35–41 (1988). (1996). 172. R.D. Koons, D.G. Havekost, C.A. Peters, ‘Analysis of 186. H.P. Longerich, B.J. Fryer, D.F. Strong, ‘Trace Analysis Gunshot Primer Residue Collection Swabs Using Flame- of Natural Alloys by Inductively Coupled Plasma/Mass less Atomic Absorption Spectrophotometry and Induc- Spectrometry (ICP/MS): Application to Archaeological tively Coupled Plasma/Atomic Emission Spectropho- Native Silver Artifacts’, Spectrochim. Acta, Part B, 42, tometry: Effects of a Modified Extraction Procedure 101–109 (1987). and Storage of Standards’, J. Forensic Sci., 34, 218–221 187. R.R. Barefoot, ‘Determination of the Precious Met- (1989). als in Geological Materials by Inductively Coupled 173. L. Varetto, ‘The Use of Plasma Ashing on Samples for Plasma Mass Spectrometry’, J. Anal. At. Spectrom., 13, Detection of Gunshot Residues with Scanning Elec- 1077–1084 (1998). tron Microscopy and Energy-dispersive X-ray Analysis 188. R. Matschat, M. Czerwensky, M. Hamester, S. Pattberg, (SEM/EDXA)’, J. Forensic Sci., 35, 964–970 (1990). ‘Investigations Concerning the Analysis of High-purity 174. D.G. Havekost, C.A. Peters, R.D. Koons, ‘Barium and Metals (Cd, Cu, Ga, and Zn) by High-resolution Induc- Antimony Distributions on the Hands of Nonshooters’, tively Coupled Plasma Mass Spectrometry’, Fresenius’ J. J. Forensic. Sci., 35, 1096–1114 (1990). Anal. Chem., 359, 418–423 (1997). 175. W.A. MacCrehan, K.D. Smith, W.F. Rowe, ‘Sampling 189. J.C. Van Loon, R.R. Barefoot, ‘Rocks, Water, and Protocols for the Detection of Smokeless Powder Biogeochemical Materials’, in Determination of the Residues Using Capillary Electrophoresis’, J. Forensic Precious Metals: Selected Instrumental Methods, Wiley, Sci., 43, 119–124 (1998). Chichester, 175–220, 1991. 176. G.M. Triplett, ‘Gunshot Residue: A Review of Analyti- 190. D.M. Hughes, D.C. Gregoire, H. Naka, C.L. Chakra- cal Techniques’, Forensic Sci. Dig., 5, 194–210 (1979). barti, ‘Determination of Trace Amounts of Phosphorus 177. G. Gonzales, A Simple Method for Concentrating in High Purity Iron by Electrothermal Vaporization Gunshot Residue Particles, FBI Laboratory Archived Inductively Coupled Plasma Mass Spectrometry’, Spec- Research Materials and Notes, 1979. trochim. Acta, Part B, 53, 1079–1085 (1998). 178. C. Vandecasteele, G. Vermeir, R. Dams, ‘Element Con- 191. S.D. Tanner, V.I. Baranov, ‘Theory, Design, and Oper- centration in the Air of an Indoor Shooting Range’, ation of a Dynamic Reaction Cell for ICPMS’, At. Environ. Tech. Lett., 9, 1287–1294 (1988). Spectrosc., 20, 45–52 (1999). 179. J. Borszeki, E. Gegus, P. Halmos, E. Mako, ‘Quality 192. D.S. Bollinger, A.J. Schleisman, ‘Analysis of High Purity Control of Industrial Alloys Using ICPAES and Pattern Acids Using a Dynamic Reaction Cell ICPMS’, At. Recognition’, Can. J. Appl. Spectrosc., 37, 1–5 (1992). 180. R.C. Carpenter, ‘The Analysis of Casework Sized Alloy Spectrosc., 20, 60–63 (1999). Fragments by Inductively Coupled Plasma/Optical Emis- 193. K. Neubauer, U. Vollkopf, ‘The Benefits of a Dynamic sion Spectrometry (ICP/OES) Using Discrete Nebuliza- Reaction Cell to Remove Carbon- and Chloride-based tion’, Forensic Sci. Int., 27, 165–170 (1985). Spectral Interferences by ICPMS’, At. Spectrosc., 20, 181. R.D. Koons, C.A. Peters, R.A. Merrill, ‘Forensic Com- 64–68 (1999). parison of Household Aluminum Foils Using Elemental 194. D.R. Bandura, S.D. Tanner, ‘Effect of Collisional Damp- Composition by Inductively Coupled Plasma/Atomic ing in the Dynamic Reaction Cell on the Precision of Emission Spectrometry’, J. Forensic Sci., 38, 302–315 Isotope Ratio Measurements’, At. Spectrosc., 20, 69–72 (1993). (1999). 182. X. Feng, G. Horlick, ‘Analysis of Aluminum Alloys 195. E. Debrah, G. Legere, ‘Improving Sensitivity and Detec- Using Inductively Coupled Plasma and Glow Discharge tion Limits in ICPMS with a Novel High-efficiency Mass Spectrometry’, J. Anal. At. Spectrom., 9, 823–831 Sample Introduction System’, At. Spectrosc., 20, 73–77 (1994). (1999). 183. A.G. Coedo, M.T. Dorado, I. Padilla, F.J. Alguacil, ‘Use 196. M.P. Heyworth, J.R. Hunter, S.E. Warren, The Role of Boric Acid to Improve the Microwave-assisted of Inductively Coupled Plasma Spectrometry in Glass Dissolution Process to Determine Fluoride Forming Ele- Provenance Studies, contribution prepared for a meeting ments in Steels by Flow Injection Inductively Coupled on The Chemical Analysis of Roman Pottery, King’s Plasma Mass Spectrometry’, J. Anal. At. Spectrom., 13, College, May, 1984. 1193–1197 (1998). 197. R.F. Coleman, G.C. Goode, ‘Comparison of Glass Frag- 184. D.A. Wynn, ‘A Complete Dissolution Procedure for ments by Neutron Activation Analysis’, J. Radioanal. SnPb Solders Using Nitric and Hydrochloric Acids Chem., 15, 367–388 (1973).

198. L.T. Atalla, F.W. Lima, ‘An Actual Case of Glass Debris 212. E.F. Cromwell, P. Arrowsmith, ‘Semiquantitative Anal- Identification by NAA in an Automobile Accident’, ysis with Laser Ablation Inductively Coupled Plasma Radiochem. Radioanal. Lett., 3, 13–22 (1970). Mass Spectrometry’, Anal. Chem., 67, 131–138 (1995). 199. J.C. Hughes, T. Catterick, G. Southeard, ‘The Quanti- 213. A. Raith, R.C. Hutton, I.D. Abell, J. Crighton, ‘Non- tative Analysis of Glass by Atomic Absorption Spec- destructive Sampling Method of Metals and Alloys troscopy’, Forensic Sci., 8, 217–227 (1976). for Laser Ablation Inductively Coupled Plasma Mass 200. T. Catterick, C.D. Wall, ‘Rapid Analysis of Small Spectrometry’, J. Anal. At. Spectrom., 10, 591–594 Glass Fragments by Atomic-absorption Spectroscopy’, (1995). Talanta, 25, 573–577 (1978). 214. T.E. Jeffries, N.J.G. Pearce, W.T. Perkins, A. Raith, 201. D.A. Hickman, ‘Elemental Analysis and the Discrimi- ‘Chemical Fractionation During Infrared and Ultravi- nation of Sheet Glass Samples’, Forensic Sci. Int., 23, olet Laser Ablation Inductively Coupled Plasma Mass 213–223 (1983). Spectrometry – Implications for Mineral Microanalysis’, 202. D.A. Hickman, ‘Glass Types Identified by Chemical Anal. Commun., 33, 35–39 (1996). Analysis’, Forensic Sci. Int., 33, 23–46 (1987). 215. D. Gunther, R. Frischknecht, C.A. Heinrich, H.-J. Ka- 203. R.D. Koons, C. Fiedler, R.C. Rawalt, ‘Classification and hlert, ‘Capabilities of an Argon Fluoride 193 nm Excimer Discrimination of Sheet and Container Glasses by Induc- Laser for Laser Ablation Inductively Coupled Plasma tively Coupled Plasma/Atomic Emission Spectrometry Mass Spectrometry Microanalysis of Geological Materi- and Pattern Recognition’, J. Forensic Sci., 33, 49–67 als’, J. Anal. At. Spectrom., 12, 939–944 (1997). (1988). 216. R.E. Russo, X. Mao, O.V. Borisov, ‘Laser Ablation 204. R.D. Koons, C.A. Peters, P.S. Rebbert, ‘Comparison of Sampling’, Trends Anal. Chem., 17, 461–469 (1998). Refractive Index, Energy Dispersive X-ray Fluorescence 217. A.A. van Heuzen, ‘Analysis of Solids by Laser Abla- and Inductively Coupled Plasma Atomic Emission tion/Inductively Coupled Plasma/Mass Spectrometry’, Spectrochim. Acta, Part B, 46, 1803–1817 (1991). Spectrometry for Forensic Characterization of Sheet 218. P. van de Weijer, P.J.M.G. Vullings, W.L.M. Baeten, Glass Fragments’, J. Anal. At. Spectrom., 6, 451–456 W.J.M. de Last, ‘Determination of Uranium and Tho- (1991). rium in Aluminum with Flow Injection and Laser 205. A. Zurhaar, L. Mullings, ‘Characterization of Forensic Ablation Inductively Coupled Plasma Mass Spectrome- Glass Samples Using Inductively Coupled Plasma Mass try’, J. Anal. At. Spectrom., 6, 609–614 (1991). Spectrometry’, J. Anal. At. Spectrom., 5, 611–617 (1990). 219. H. Yasuhara, T. Okano, Y. Matsumura, ‘Determination 206. T. Parouchais, I.M. Warner, L.T. Palmer, H. Kobus, of Trace Elements in Steel by Laser Ablation Inductively ‘The Analysis of Small Glass Fragments Using Induc- Coupled Plasma Mass Spectrometry’, Analyst, 117, tively Coupled Plasma Mass Spectrometry’, J. Forensic 395–399 (1992). Sci., 41, 351–360 (1996). 220. E.F. Cromwell, P. Arrowsmith, ‘Fractionation Effects 207. W.T. Perkins, N.J.G. Pearce, T.E. Jeffries, ‘Laser Abla- in Laser Ablation Inductively Coupled Plasma Mass tion Inductively Coupled Plasma Mass Spectrometry: Spectrometry’, Appl. Spectrosc., 49, 1652–1660 (1995). A New Technique for the Determination of Trace and 221. Y. Ishibashi, ‘Rapid Analysis of Steel by Inductively Ultra-trace Elements in Silicates’, Geochim. Cosmochim. Coupled Plasma/Atomic Emission Spectrometry and Acta, 57, 475–482 (1993). Mass Spectrometry with Laser Ablation Solid Sampling’, 208. C. Ludke, E. Hoffman, J. Skole, ‘Comparative Studies Iron Steel Inst. Jpn. Int., 37, 885–891 (1997). on Metal Determination in Airborne Particulates by 222. A.I. Yuzefovsky, D.E. Miser, ‘Analysis of Discolored LA/ICPMS and Furnace Atomization Non-thermal Aluminum Foil by Laser Ablation Inductively Coupled Excitation Spectrometry’, Fresenius’ J. Anal. Chem., 350, Plasma Mass Spectrometry and Scanning Electron 272–276 (1994). Microscopy’, Appl. Spectrosc., 52, 629–637 (1998). 209. K. Ulens, L. Moens, R. Dams, S. Van Winckel, L. Van- 223. K.E. Jarvis, J.G. Williams, ‘Laser Ablation Inductively develde, ‘Study of Element Distributions in Weathered Coupled Plasma Mass Spectrometry (LA/ICPMS): A Marble Crusts Using Laser Ablation Inductively Cou- Rapid Technique for the Direct, Quantitative Deter- pled Plasma Mass Spectrometry’, J. Anal. At. Spectrom., mination of Major, Trace and Rare-earth Elements in 9, 1243–1248 (1994). Geological Samples’, Chem. Geol., 106, 251–262 (1993). 210. D.J. Kontak, S. Jackson, ‘Laser-ablation ICP/MS Micro- 224. K.E. Jarvis, J.G. Williams, S.J. Parry, E. Bertalan, analysis of Calcite Cement from a Mississippi-valley-type ‘Quantitative Determination of the Platinum-group Ele- Zn–Pb Deposit, Nova Scotia: Dramatic Variability in ments and Gold Using NiS Fire Assay with Laser REE Content on Macro- and Micro-scales’, Can. Miner., Ablation/Inductively Coupled Plasma/Mass Spectrom- 33, 445–467 (1995). etry’, Chem. Geol., 124, 37–46 (1995). 211. F.E. Lichte, ‘Determination of Elemental Content of 225. S. Chenery, J.M. Cook, M. Styles, E.M. Cameron, Rocks by Laser Ablation Inductively Coupled Plasma ‘Determination of the Three-dimensional Distributions Mass Spectrometry’, Anal. Chem., 67, 2479–2485 (1995). of Precious Metals in Sulfide Minerals by Laser Ablation

Microprobe/Inductively Coupled Plasma/Mass Spec- 231. D. Figg, M.S. Kahr, ‘Elemental Fractionation of Glass trometry (LAMP/ICPMS)’, Chem. Geol., 124, 55–65 Using Laser Ablation Inductively Coupled Plasma Mass (1995). Spectrometry’, Appl. Spectrosc., 51, 1185–1192 (1997). 226. R.J. Watling, H.K. Herbert, I.S. Barrow, A.G. Thomas, 232. V. Kanicky, V. Otruba, J.-M. Mermet, ‘Use of Internal ‘Analysis of Diamonds and Indicator Minerals for Standardization to Compensate for a Wide Range of Diamond Exploration by Laser Ablation/Inductively Absorbance in the Analysis of Glasses by UV Laser Coupled Plasma Mass Spectrometry’, Analyst, 120, Ablation Inductively Coupled Plasma Atomic Emission 1357–1364 (1995). Spectrometry’, Appl. Spectrosc., 52, 638–642 (1998). 227. P.M. Outridge, ‘Potential Applications of Laser Abla- 233. M.D. Norman, W.L. Grifﬁn, N.J. Pearson, M.O. Garcia, tion ICPMS in Forensic Biology and Exploration Geo- S.Y. O’Reilly, ‘Quantitative Analysis of Trace Element chemistry’, Spectroscopy, 11, 21–26 (1996). Abundances in Glasses and Minerals: A Comparison 228. J.L. Imbert, P. Telouk, ‘Application of Laser Ablation of Laser Ablation Inductively Coupled Plasma Mass ICPMS to Elemental Analysis of Glasses’, Mikrochim. Spectrometry, Solution Inductively Coupled Plasma Acta, 110, 151–160 (1993). Mass Spectrometry, Proton Microprobe and Electron 229. J.A. Westgate, W.T. Perkins, R. Fuge, N.J.G. Pearce, Microprobe Data’, J. Anal. At. Spectrom., 13, 477–482 A.G. Wintle, ‘Trace-element Analysis of Volcanic Glass (1998). Shards by Laser Ablation Inductively Coupled Plasma 234. R.J. Watling, B.F. Lynch, D. Herring, ‘Use of Laser Mass Spectrometry: Application to Tephrochronological Ablation Inductively Coupled Plasma Mass Spectrome- Studies’, Appl. Geochem., 9, 323–335 (1994). try for Fingerprinting Scene of Crime Evidence’, J. Anal. 230. J. Stix, G. Gauthier, J.N. Ludden, ‘A Critical Look at At. Spectrom., 12, 195–203 (1997). Quantitative Laser Ablation ICPMS Analysis of Natural 235. T.A. Rooney, ‘Rev Up Your Search Engines’, Today’s and Synthetic Glasses’, Can. Miner., 33, 435–444 (1995). Chemist at Work, 7, 17–20 (1998).