Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1986 Evaluation of a direct injection nebulizer interface for flow injection analysis and high performance liquid chromatography with inductively coupled plasma-atomic emission spectroscopic detection Kimberly E. LaFreniere Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Analytical Chemistry Commons Recommended Citation LaFreniere, Kimberly E., "Evaluation of a direct injection nebulizer interface for flow injection analysis and high performance liquid chromatography with inductively coupled plasma-atomic emission spectroscopic detection " (1986). Retrospective Theses and Dissertations. 8013. https://lib.dr.iastate.edu/rtd/8013 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. 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EVALUATION OF A DIRECT INJECTION NEBULIZER INTERFACE FOR FLOW INJECTION ANALYSIS AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA-ATOMIC EMISSION SPECTROSCOPIC DETECTION Iowa State University PH.D. 1986 University Microfilms Internâtionâl 300 N. zeeb noad, Ann Arbor, Ml 48106 Evaluation of a direct injection nebulizer interface for flow injection analysis and high performance liquid chromatography with inductively coupled plasma-atomic emission spectroscopic detection by Kimberly E. LaFreniere A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Chemistry Major; Analytical Chemistry Approved; Signature was redacted for privacy. In Charge of Major Work Signature was redacted for privacy. le Ma]or Depar Signature was redacted for privacy. Iowa State University Ames, Iowa 1986 ii TABLE OF CONTENTS DEDICATION V CHAPTER I. INTRODUCTION 1 Review of the Literature 1 Flame atomic absorption spectroscopy (FAAS) 3 Atomic fluorescence spectroscopy (AFS) 31 Graphite furnace atomic absorption spectroscopy (GFAAS) 31 Microwave induced plasma atomic emission detectors 32 Direct current plasma atomic emission detectors 38 Inductively coupled plasma-atomic emission detectors 39 Statement of Problem 46 CHAPTER II. EXPERIMENTAL FACILITIES AND OPERATING CONDITIONS 51 Plasma Operating Conditions 51 Methods of Saitple Introduction 51 Direct injection nebulizer interface 51 Pneumatic nebulizer interface 58 Ultrasonic nebulizer interface 59 Detection Facilities 60 Single element detection 60 Simultaneous, multielement detection 60 Analytical Figures of Merit Studies 64 Preparation of reference solutions 64 Interelement effects 65 Applications to Synthetic and Real Samples 65 iii CHAPTER III. ANALYTICAL FIGURES OF MERIT 67 General 67 Results and Discussion 67 Detection limit comparisons 67 Limits of detection 68 Comparison of detection limits for other microliter 72 solution volume introduction methods to the FIA-DIN approach Reproducibility 78 Linear dynamic range 79 Interelement effect studies 79 Fundamental considerations 87 CHAPTER IV. ANALYTICAL PERFORMANCE ON SAMPLES 93 Synthetic Mixtures 93 Arsenic species 93 Selenium species 95 Chromium species 97 Cr species in "pure" Cr salts 99 Sulfur species 99 Simultaneous multielement detection 103 Bourbon Vanilla Extract Analyses 105 Elemental analysis 105 HPLC-DIN-ICP-AES analysis 105 Energy-related Materials 108 Shale oil process waters 112 Coal liquifaction products 118 Shale oil, crude oil, and SRC II analyses 130 iv CHAPTER V. CONCLUSIONS AND SUMMARY 163 CHAPTER VI. SUGGESTIONS FOR FUTURE RESEARCH 168 LITERATURE CITED 170 ACKNCWLEDGEMENTS 182 APPENDIX A. COMPILATION OF ACRONYMS 184 APPENDIX B. PLASMA EXCITATION TEMPERATURE MEASUREMENTS 187 Introduction 187 Theoretical Considerations 189 Experimental Apparatus and Procedures 193 Results and Discussion 193 V DEDICATION In loving memory of ity parents, Dean and Billie Lawrence. 1 CHAPTER I. INTRODUCTIONf Review of the Literature The toxicological impact of any given element on a biological system is greatly dependent upon the form in which that element exists (e.g., zerovalent, cationic, anionic, or bound to some organic counterpart). Typical cases in point are the biochemical effects of arsenic, for which arsenic(lll), or arsenite, compounds are the most toxic. Inorganic arsenicals have been shown to coagulate proteins, to complex coenzymes, and to uncouple the energy-yielding process of phosphorylation (1). In the past 15 years, a heightened awareness regarding the toxic effects of certain elements in a wide variety of sample matrices has stimulated much interest in metal speciation. Metal speciation, or the separation and identification of the individual metallic forms that exist in a given matrix, has not been a trivial task, as documented in the many excellent reviews found in the literature (2-7). Intuitively, the combination of some mode of species separation and an appropriate detector should provide the analyst with a powerful means of identifying metal-containing species. Gas chromatography (GC) or high performance liquid chromatography (HPLC) are the most widely accepted methods of separating compounds. Indeed, GC has been applied to the separation of many metal chelates and organometallic compounds, but its use is primarily limited to neutral, volatile, low molecular weight species of high thermal stability (8). Although the gas chromatographic ^Definitions of acronyms are given in Appendix A. 2 detection and determination of many involatile or thermally labile conçounds can be made feasible by derivatization, this technique is often difficult to apply to "real world" sample matrices that contain mixtures of confounds of unknown structure (9). For these reasons, investigators have turned toward HPLC as the primary method of separating compounds for thermally unstable substances, such as biologically active materials, high molecular weight organic coitpounds, polymers, and organometallic compounds (8,10-13). The HPLC technique offers versatility in separation mechanisms, including liquid-liquid partition, liquid-solid adsorption, reverse-phase partition, ion exchange, and size exclusion, all of which have been enployed for metal speciation studies. Although the technology required to perform the HPLC separation of metal-containing species is generally available, sensitive and specific detection of the metal of interest can best be achieved through the use of element-specific detectors. Conventional HPLC detectors, such as the refractive index (RI), ultraviolet (UV), fluorescence (FL), electrochemical (EC), flame ionization (FI), and infrared (IR) vary in degree of selectivity and applicability (14,15). Atomic spectroscopic detectors, on the other hand, are highly specific and are applicable to a variety of sample matrices. Among the various atomic spectroscopic detectors, flame atomic absorption spectroscopy (FAAS), graphite furnace atomic absorption spectroscopy (GEAAS), and flame or plasma atomic fluorescence spectroscopy (APS), as well as microwave-induced plasma (MIP), direct-current plasma (DCP), and inductively-coupled plasma (ICP) atomic emission spectroscopy hold the most promise as element-specific detectors for HPLC. Indeed, 125 publications on atomic, element-specific detectors have appeared in the 3 literature in the last 10 to 15 years. Of the atomic spectroscopic detectors, emission sources are the most readily adapted to multielement monitoring, and many researchers agree that plasma emission spectroscopy will eventually be the method of choice for simultaneous, multielement, element-specific chromatographic detection (2-5). It should be noted, however, that non-specific, on-line HPLC detectors of molecular