DOCSLIB.ORG

Determination of End Groups of Synthetic Polymers by Matrix-Assisted Laser Desorption/ Ionization: High-Energy Collision-Induced Dissociation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Determination of End Groups of Synthetic Polymers by Matrix-Assisted Laser Desorption/ Ionization: High-Energy Collision-Induced Dissociation Anal. Chem. 1999, 71, 3637-3641 Determination of End Groups of Synthetic Polymers by Matrix-Assisted Laser Desorption/ Ionization: High-Energy Collision-Induced Dissociation Andrew R. Bottrill, Anastassios E. Giannakopulos, Carl Waterson, David M. Haddleton, Ken S. Lee, and Peter J. Derrick* Institute of Mass Spectrometry and Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom Matrix-assisted laser desorption/ionization has been com- MALDI-time-of-flight (TOF) mass spectrometry to obtain values bined with high-energy collision-induced dissociation for for molecular mass averages, Mn and Mw, especially in combination the analysis of poly(ethylene glycols) with butanoyl, with size exclusion chromatography.17-20 benzoyl and acetyl end groups, using novel technology Techniques of polymer synthesis are becoming increasingly comprising a magnetic-sector mass spectrometer and ion sophisticated with a move toward the attempt to design macro- buncher with an in-line quadratic-field ion mirror. High- molecules for specific application. This has usually been centered energy (>8 keV) collision-induced dissociation facilitated around living, or pseudoliving, polymerization which allows the unambiguous end-group determination of these polymers, incorporation of different functionalities at precise positions by providing masses of end groups and structural informa- judicious choice of reaction conditions.28-34 For example, R and tion. The high-energy collision-induced dissociation also â terminally functional polymers may have very different proper- provided information regarding repeat units. (12) Williams, J. B.; Gusev, A. I.; Hercules, D. M. Macromolecules 1997, 30, 3781-3787. (13) Montaudo, G.; Montaudo, M. S.; Puglisi, C.; Samperi, F.; Sepulchre M. Mass spectrometry of synthetic polymers is gaining in popular- Macromol. Chem. Phys. 1996, 197, 2615-2625. (14) Zammit, M. D.; Davis, T. P.; Haddleton, D. M.; Suddaby, K. G. Macromol- ity due to the unprecedented high-quality information accessible ecules 1997, 30, 1915-1920. to the synthetic polymer chemist. Matrix-assisted laser desorp- (15) Guttman, C. M.; Blair, W. R.; Danis, P. O. J. Polym. Sci., Part B: Polym. tion/ionization (MALDI) has been shown to be an especially Phys. 1997, 35, 2409-2419. (16) Duncalf, D. J.; Wade, H. J.; Waterson, C.; Derrick, P. J.; Haddleton, D. M.; 1-8 useful tool for the direct analysis of synthetic polymers. The McCamley, A. Macromolecules 1996, 29, 6399-6403. results obtained for polymers from MALDI mass spectrometry (17) Nielen, M. W. F. Anal. Chem. 1998, 70, 1563-1568. experiments typically give qualitative molecular weight information (18) Montaudo, M. S.; Puglisi, C.; Samperi, F.; Montaudo, G. Rapid Commun. Mass Spectrom. 1998, 12, 519-528. but normally not structural information. Nevertheless, MALDI has (19) Jackson, C.; Larsen, B.; McEwen, C. Anal. Chem. 1996, 68, 1303-1308. been utilized to gain information on monomer reactivity ratios,9 (20) Kassis, C. E.; DeSimone, J. M.; Linton, R. W.; Lange, G. W.; Friedman, R. end groups,10-13 and mechanisms of polymerization.14-16 Many M. Rapid Commun. Mass Spectrom. 1997, 11, 1134-1138. (21) Barber, M.; Bordoli, R. S.; Sedgewick, R. D.; Tyler, A. N. Nature 1981, attempts, with a variety of success, have also been made to use 293, 270-275. (22) Arberth, W.; Straub, K. M.; Burlingame, A. L. Anal. Chem. 1982, 54, 2029- (1) Bahr, U.; Depe A.; Karas, M.; Hillenkamp, F.; Giessmann, U. Anal. Chem. 2034. 1992, 64, 2866-2869. (23) Craig, A. G.; Derrick, P. J. J. Chem. Soc., Chem. Commun. 1985, 891- (2) Belu, A. M.; DeSimone, J. M.; Linton, R. W.; Lange, G. W.; Friedman, R. 892. M. J. Am. Soc. Mass Spectrom. 1996, 7,11-24. (24) Craig, A. G.; Derrick, P. J. Aust. J. Chem. 1986, 39, 1421-1434. (3) Lloyd, P. M.; Suddaby, K. G.; Varney, J. V.; Scrivener, E.; Derrick, P. J.; (25) Jackson, A. T.; Jennings, K. R.; Scrivens, J. H. J. Am. Soc. Mass Spectrom. Haddleton, D. M. Eur. Mass Spectrom. 1995, 1, 293-300. 1997, 8,76-85. (4) Hoberg, A.-M.; Haddleton, D. M.; Derrick, P. J. Eur. Mass Spectrom. 1997, (26) Jackson, A. T.; Yates, H. T.; Scrivens, J. H.; Critchley, G.; Brown, J.; Green, 3, 471-473 M. R.; Bateman, R. H. Rapid Commun. Mass Spectrom. 1996, 10, 1668- (5) Creel, H. S. Trends Pol. Sci. 1993, 1, 336. 1674. (6) Jackson, C. A.; Simonsick, W. J. Curr. Opin. Solid. State Mater. Sci. 1997, (27) Andersen, U. N.; Colburn, A. W.; Makarov, A. A.; Raptakis, E. N.; Reynolds, 2, 661-667. D. J.; Derrick, P. J.; Davis, S. C.; Hoffman, A. D.; Thomson, S. Rev. Sci. (7) Danis, P. O.; Karr, D. E.; Simonsick, W. J.; Wu, D. T. Macromolecules 1995, Instrum. 1998, 69, 1650-1660. 28, 1229-1232. (28) Webster, O. W. Science 1991, 251, 887-893. (8) Danis, P. O.; Karr, D. E.; Xiong, Y.; Owens, K. G. Rapid Commun. Mass (29) Davis, T. P.; Haddleton, D. M.; Richards, S. N. J. Macromol. Sc., Rev. Spectrom. 1996, 10, 862-868. Macromol. Chem. Phys. 1994, C34, 243-324. (9) Suddaby, K. G.; Hunt, K. H.; Haddleton, D. M. Macromolecules 1996, 29, (30) Haddleton, D. M.; Waterson, C.; Derrick, P. J.; Jasieczek, C.; Shooter, A. J. 8642-8649. Chem. Commun. 1997, 683-684. (10) Maloney, D. R.; Hunt, K. H.; Lloyd, P. M.; Muir, A. V. G.; Richards, S. N.; (31) Matyjaszewski, K. J. Phys. Org. Chem. 1995, 8, 197-207. Derrick, P. J.; Haddleton, D. M. J. Chem. Soc., Chem. Commun. 1995, 561- (32) Yeates, S. G.; Richards, S. N. Surf. Coat. Int. 1996, 10, 437-442. 562. (33) Matyjaszewski, K.; Wang, J.-L.; Grimaud, T. J.; Shipp, D. A. Macromolecules (11) Montaudo, G.; Montaudo, M. S.; Puglisi, C.; Samperi, F. J. Pol. Sci. A Pol. 1998, 31, 1527-1534. Chem. 1996, 34, 439-447. (34) Perec, V.; Kim, H. J.; Barboiu, B. Macromolecules 1997, 30, 8526-8528. 10.1021/ac990523t CCC: $18.00 © 1999 American Chemical Society Analytical Chemistry, Vol. 71, No. 17, September 1, 1999 3637 Published on Web 07/24/1999 ties in certain applications. Thus it is important for techniques to be developed that can confirm, or refute, synthetically targeted macromolecular structures. In addition to empirical molecular mass data, it is important to be able to determine information regarding the end groups of and the sequence of monomers/ groups within a synthetic macromolecule. Tandem mass spec- trometry can in principle provide such structural information for a synthetic polymer. Tandem mass spectrometry has been widely used in the biological area, combined with ionization techniques such as liquid secondary ion mass spectrometry (LSIMS)21,22 and electrospray ionization. Early investigations with field desorption showed how tandem mass spectrometry could be used to investigate the structure of synthetic polymers.23,24 End-group information for poly(methyl methacrylate) (PMMA) has been derived from LSIMS using collision-induced dissociation (CID) at 4-keV collision energy in magnetic-sector instruments.25 The envelopes of peaks due to cationized molecules in these LSIMS experiments were centered at lower mass-to-charge ratios than the molecule-ion envelopes with MALDI for the same Figure 1. Structures of the differing end-terminated poly(ethylene polymers, presumably as a result of reduced ionization efficiency glycol) oligomers chosen for MALDI-CID. in the high-mass region in the LSIMS case. MALDI-CID results for poly(ethylene glycol)s (PEGs), MALDI-CID results for PMMA, possible full control over the laboratory-frame collision energy. and LSIMS-CID results for PMMAs have been reported by The expectation was that the high laboratory-frame collision (103- 4 Jackson et al.,26 utilizing laboratory collision energy of 800 eV on 10 eV) accessible in MAG-TOF would be advantageous as regards a magnetic-sector/orthogonal TOF instrument. For the PMMAs, fragmentation of large ions. The high laboratory-frame collision better signal-to-noise ratios were reported for the MALDI-CID energies access interaction times shorter than those accessible spectra compared to the LSIMS tandem mass spectra, due at least at lower energies. For example, center-of-mass collision energy in part to the higher sensitivities of MALDI. With orthogonal TOF, is approximately the same for a large ion at a laboratory-frame ion energies prior to orthogonal acceleration, and hence collision collision energy of 800 eV with Ar collision gas as at a laboratory- energies, need to be low (ideally <100 eV), and the 800-eV frame collision energy of 8000 eV with He collision gas. The collision energy employed in these experiments would be very physical processes differ, however, as is evidenced by the results much an upper limit. The restriction to low collision energies is presented in this paper, with one significant difference being the the major shortcoming of orthogonal TOF in the context of tandem interaction times. The results presented here are consistent with mass spectrometry. The novel instrument27 used in this study has the fragmentation induced by collision being more localized within E been designed to overcome any limitation or restriction of collision the macromolecule at the higher LAB's and shorter interaction times, when energy transfer must occur within a smaller time energy to low values (see below). window. In this paper, we report CID experiments with poly(ethylene glycol)s with different R, terminal functionalities performed using â EXPERIMENTAL SECTION novel hybrid magnetic-sector/time-of-flight instrumentation (MAG- Cationized molecules were produced using a MALDI ion 27 TOF). The instrumentation consisted of a Kratos Concept H source and accelerated to 8 keV at the ion source. Particular ions double-focusing magnetic sector and associated ion buncher as were selected for fragmentation by adjusting the magnetic field the first mass spectrometer (MS-1) and a planar hyperbolic (so- strength and exit slit in MS-1.
Load more

Recommended publications
  • About Magnetic Sector Mass Spec- Trometers
    About Magnetic Sector Mass Spec- trometers Double-focusing magnetic sector mass spectrometers provide high sensitivity, high resolution, and a reproducibility that is unmatched in any other kind of mass analyzer. A double-focusing magnetic sector mass spectrometer has at least four components: . An ion source in which ions are formed and accelerated to energies of up to as high as 10 kilovolts. A magnetic sector with a magnetic field that exerts a force perpendicular to the ion mo- tion to deflect ions according to their momentum. An electric sector with an electric field that exerts a force perpendicular to the ion mo- tion to deflect ions according to their kinetic energy. A detector that produces a response that is proportional to the number of ions. Slits are placed in the ion path to define the positions and energies of the ions that strike the detector. In general, decreasing the slit widths increases the mass resolution but re- duces the number of ions that are detected. Additional electrostatic lenses are com- monly used to shape and deflect the ion beam to optimize peak shape and maximize ion beam transmission from the source to the detector. JEOL uses octapole and quadrupole focusing lenses to simplify the ion optical design. Collision chambers in the first field-free region (just after the ion source) and second field-free region (just after the magnet and before the electric sector) are used to induce ions to fragment in collision-induced-dissociation experiments (MS/MS). The term "double-focusing" refers to the fact that the combination of electric and mag- netic sectors focuses ions according to both direction and energy to provide higher reso- lution than can be obtained with a single magnetic sector.
    [Show full text]
  • Modern Mass Spectrometry
    Modern Mass Spectrometry MacMillan Group Meeting 2005 Sandra Lee Key References: E. Uggerud, S. Petrie, D. K. Bohme, F. Turecek, D. Schröder, H. Schwarz, D. Plattner, T. Wyttenbach, M. T. Bowers, P. B. Armentrout, S. A. Truger, T. Junker, G. Suizdak, Mark Brönstrup. Topics in Current Chemistry: Modern Mass Spectroscopy, pp. 1-302, 225. Springer-Verlag, Berlin, 2003. Current Topics in Organic Chemistry 2003, 15, 1503-1624 1 The Basics of Mass Spectroscopy ! Purpose Mass spectrometers use the difference in mass-to-charge ratio (m/z) of ionized atoms or molecules to separate them. Therefore, mass spectroscopy allows quantitation of atoms or molecules and provides structural information by the identification of distinctive fragmentation patterns. The general operation of a mass spectrometer is: "1. " create gas-phase ions "2. " separate the ions in space or time based on their mass-to-charge ratio "3. " measure the quantity of ions of each mass-to-charge ratio Ionization sources ! Instrumentation Chemical Ionisation (CI) Atmospheric Pressure CI!(APCI) Electron Impact!(EI) Electrospray Ionization!(ESI) SORTING DETECTION IONIZATION OF IONS OF IONS Fast Atom Bombardment (FAB) Field Desorption/Field Ionisation (FD/FI) Matrix Assisted Laser Desorption gaseous mass ion Ionisation!(MALDI) ion source analyzer transducer Thermospray Ionisation (TI) Analyzers quadrupoles vacuum signal Time-of-Flight (TOF) pump processor magnetic sectors 10-5– 10-8 torr Fourier transform and quadrupole ion traps inlet Detectors mass electron multiplier spectrum Faraday cup Ionization Sources: Classical Methods ! Electron Impact Ionization A beam of electrons passes through a gas-phase sample and collides with neutral analyte molcules (M) to produce a positively charged ion or a fragment ion.
    [Show full text]
  • An Introduction to Mass Spectrometry
    An Introduction to Mass Spectrometry by Scott E. Van Bramer Widener University Department of Chemistry One University Place Chester, PA 19013 [email protected] http://science.widener.edu/~svanbram revised: September 2, 1998 © Copyright 1997 TABLE OF CONTENTS INTRODUCTION ........................................................... 4 SAMPLE INTRODUCTION ....................................................5 Direct Vapor Inlet .......................................................5 Gas Chromatography.....................................................5 Liquid Chromatography...................................................6 Direct Insertion Probe ....................................................6 Direct Ionization of Sample ................................................6 IONIZATION TECHNIQUES...................................................6 Electron Ionization .......................................................7 Chemical Ionization ..................................................... 9 Fast Atom Bombardment and Secondary Ion Mass Spectrometry .................10 Atmospheric Pressure Ionization and Electrospray Ionization ....................11 Matrix Assisted Laser Desorption/Ionization ................................ 13 Other Ionization Methods ................................................13 Self-Test #1 ...........................................................14 MASS ANALYZERS .........................................................14 Quadrupole ............................................................15
    [Show full text]
  • Methods of Ion Generation
    Chem. Rev. 2001, 101, 361−375 361 Methods of Ion Generation Marvin L. Vestal PE Biosystems, Framingham, Massachusetts 01701 Received May 24, 2000 Contents I. Introduction 361 II. Atomic Ions 362 A. Thermal Ionization 362 B. Spark Source 362 C. Plasma Sources 362 D. Glow Discharge 362 E. Inductively Coupled Plasma (ICP) 363 III. Molecular Ions from Volatile Samples. 364 A. Electron Ionization (EI) 364 B. Chemical Ionization (CI) 365 C. Photoionization (PI) 367 D. Field Ionization (FI) 367 IV. Molecular Ions from Nonvolatile Samples 367 Marvin L. Vestal received his B.S. and M.S. degrees, 1958 and 1960, A. Spray Techniques 367 respectively, in Engineering Sciences from Purdue Univesity, Layfayette, IN. In 1975 he received his Ph.D. degree in Chemical Physics from the B. Electrospray 367 University of Utah, Salt Lake City. From 1958 to 1960 he was a Scientist C. Desorption from Surfaces 369 at Johnston Laboratories, Inc., in Layfayette, IN. From 1960 to 1967 he D. High-Energy Particle Impact 369 became Senior Scientist at Johnston Laboratories, Inc., in Baltimore, MD. E. Low-Energy Particle Impact 370 From 1960 to 1962 he was a Graduate Student in the Department of Physics at John Hopkins University. From 1967 to 1970 he was Vice F. Low-Energy Impact with Liquid Surfaces 371 President at Scientific Research Instruments, Corp. in Baltimore, MD. From G. Flow FAB 371 1970 to 1975 he was a Graduate Student and Research Instructor at the H. Laser Ionization−MALDI 371 University of Utah, Salt Lake City. From 1976 to 1981 he became I.
    [Show full text]
  • Electrification Ionization: Fundamentals and Applications
    Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 11-12-2019 Electrification Ionization: undamentalsF and Applications Bijay Kumar Banstola Louisiana State University and Agricultural and Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Analytical Chemistry Commons Recommended Citation Banstola, Bijay Kumar, "Electrification Ionization: undamentalsF and Applications" (2019). LSU Doctoral Dissertations. 5103. https://digitalcommons.lsu.edu/gradschool_dissertations/5103 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. ELECTRIFICATION IONIZATION: FUNDAMENTALS AND APPLICATIONS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Chemistry by Bijay Kumar Banstola B. Sc., Northwestern State University of Louisiana, 2011 December 2019 This dissertation is dedicated to my parents: Tikaram and Shova Banstola my wife: Laxmi Kandel ii ACKNOWLEDGEMENTS I thank my advisor Professor Kermit K. Murray, for his continuous support and guidance throughout my Ph.D. program. Without his unwavering guidance and continuous help and encouragement, I could not have completed this program. I am also thankful to my committee members, Professor Isiah M. Warner, Professor Kenneth Lopata, and Professor Shengli Chen. I thank Dr. Fabrizio Donnarumma for his assistance and valuable insights to overcome the hurdles throughout my program. I appreciate Miss Connie David and Dr.
    [Show full text]
  • Compositional Analysis of Complex Organic Mixtures by Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Zhigang Wu
    Florida State University Libraries Electronic Theses, Treatises and Dissertations The Graduate School 2004 Compositional Analysis of Complex Organic Mixtures by Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Zhigang Wu Follow this and additional works at the FSU Digital Library. For more information, please contact [email protected] THE FLORIDA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES Compositional Analysis of Complex Organic Mixtures by Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry By Zhigang Wu A Dissertation submitted to the Department of Chemistry and Biochemistry in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Degree Awarded: Spring Semester, 2004 Copyright2004 Zhigang Wu All Rights Reserved The members of the Committee approve the Dissertation of Zhigang Wu Defended on April 7, 2004. Alan G. Marshall Professor Directing Dissertation William M. Landing Outside Committee Member William T. Cooper Committee Member Timothy A. Cross Committee Member Ryan P. Rodgers Committee Member The Office of Graduate Studies has verified and approved the above named committee members. ii To my parents, Xiaohua Wu and Shiping Cao; iii ACKNOWLEDGMENTS First, I need to thank Dr. Alan G. Marshall, my academic graduate advisor and supporter. His deep and broad academic knowledge and great personality are invaluable throughout my graduate career. His wise and forecasting advices has helped me directly cut to the “point” and inspired me to discover more underneath. I also wish to acknowledge Dr. Ryan P. Rodgers, my supervisor, for his expertise, direction, and support. His initiation and development in petroleum applications have led me to a broader and better understanding of this area.
    [Show full text]
  • Liquid Injection Field Desorption/Ionization-Mass
    Liquid Injection Field Desorption/Ionization- Mass Spectrometry of Ionic Liquids Jürgen H. Gross Institute of Organic Chemistry, University of Heidelberg, Heidelberg, Germany ϩ Ten ionic liquids based on four types of organic cations, C (imidazolium, pyrrolidinium, pyridinium, and phosphonium), combined with various types of anions, AϪ, were analyzed by liquid injection field desorption/ionization- (LIFDI) mass spectrometry. For the purpose of LIFDI analysis the ionic liquids were dissolved in methanol, acetonitrile or tetrahydrofuran at Ϫ concentrationsof0.01–0.1 ␮lmL 1. The measurements were performed on a double-focusing magnetic sector instrument. In all ionic liquid LIFDI spectra, the intact cation of the compound ϩ yielded the base peak accompanied by cluster ions of the general formula [C A] and ϩ 2 occasionally [C3A2] . Tandem mass spectrometry and reconstructed ion chromatograms were employed to reveal the identity of the observed ions. Although limited to positive-ion mode, LIFDI also provided analytical information on the anions due to cluster ion formation. Depending on actual emitter condition and ionic liquid the limit of detection in survey scans was determined to 5–50 pg of ionic liquid. (J Am Soc Mass Spectrom 2007, 18, 2254–2262) © 2007 American Society for Mass Spectrometry onic liquids (ILs)have recently received widespread FD employs strong electric fields in the order of 1010 Ϫ Ϫ interest among many areas of chemical research as Vm 1 (1VÅ 1) to effect the ionization of atoms and Ithey act as highly polar thermally stable solvents in molecules [11, 12, 31]. The necessary field strength is chemical synthesis [1–3]. Consequently, there is a need normally achieved by setting whisker-bearing wires— for the development of methods for their analysis, be it so-called activated emitters [32–34]—to high electric for the sake of checking their purity, to verify their potential of typically 10–12 kV opposed to a counter absence in products from processes where ILs are electrode at ϳ2 mm distance.
    [Show full text]
  • FD) and Liquid Injection Field Desorption Ionization (LIFDI
    Soft ionization by Field Ionization (FI), Field desorption (FD) and Liquid Injection Field Desorption Ionization (LIFDI) H. Bernhard Linden Linden CMS GmbH [email protected] www.LIFDI.com 1 LINDEN CMS GmbH, 2012 Soft ionization by FI, FD and LIFDI Introduction by mouth watering soft ionization spectra 1. General and theoretical overview 2. Various instruments – identical technique 3. Automated LIFDI 4. Improved FI intensity 5. LIFDI on FT-ICR instruments 6. LIFDI of air/moisture sensitive metal complexes 7. Orbitrap with ESI-LIFDI combination 2 LINDEN CMS GmbH, 2012 FI and FD are known for soft ionization of non-polar compounds, LIFDI outperforms other MS techniques for characterization of organometallics due to its softness and convenient handling order of soft ionization References Liquid injection field desorption/ionization of transition decomposition decreases : ESI > LIFDI metal fluoride complexes Trevor A. Dransfield, Ruqia Nazir, Robin N. Perutz and “LIFDI ... gave the molecular ion peaks [M]+ as base peaks (100%) ... Adrian C. Whitwood With ESI, the compounds showed decomposition.” J. Fluorine Chem. 131, 2010, 1213-1217 loss of CO decreases : MALDI > FAB > FD *) Analysis of ruthenium carbonyl–porphyrin complexes: a comparison of matrix-assisted laser desorption/ionisation “ruthenium carbonyl complexes exhibited time-of-flight, fast-atom bombardment and field desorption abundant carbon monoxide (CO) loss in MALDI-TOF-MS and still a mass spectrometry, measurable CO loss in FAB-MS. Only FD-MS yielded the molecular ion M. Frauenkron, A. Berkessel and J. H. Gross as the base peak of the spectra in all cases.” Eur. J. Mass Spectrom. 1997, 3, 427 - 438 “fragmentation decreases Comparison of electrospray mass spectrometry with other soft ionization techniques for the characterization of cationic along the series FAB > ESI > FD “ *) π-hydrocarbon organometallic complexes , L.
    [Show full text]
  • The MALDI Process and Method 1
    1 1 The MALDI Process and Method Franz Hillenkamp , Thorsten W. Jaskolla , and Michael Karas 1.1 Introduction Matrix-assisted laser desorption/ionization ( MALDI ) is one of the two “soft” ioni- zation techniques besides electrospray ionization ( ESI ) which allow for the sensi- tive detection of large, nonvolatile and labile molecules by mass spectrometry. Over the past 27 years, MALDI has developed into an indispensable tool in analyti- cal chemistry, and in analytical biochemistry in particular. In this chapter, the reader will be introduced to the technology as it stands now, and some of the underlying physical and chemical mechanisms as far as they have been investi- gated and clarifi ed to date will be discussed. Attention will also be focused on the central issues of MALDI, that are necessary for the user to understand for the effi cient application of this technique. As an in-depth discussion of these topics is beyond the scope of this chapter, the reader is referred to recent reviews [1–4] . Details of the current state of instrumentation, including lasers and their coupling to mass spectrometers, will be presented in Chapter 2 . As with most new technologies, MALDI came as rather a surprise even to the experts in the fi eld on the one hand, but also evolved from a diversity of prior art and knowledge on the other hand. The original notion had been that (bio)mole- cules with masses in excess of about 500–1000 Da could not be isolated out of their natural (e.g., aqueous) environment, and even less be charged for an analysis in the vacuum of a mass spectrometer without excessive and unspecifi c fragmenta- tion.
    [Show full text]
  • 82756031.Pdf
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Do Charge-Remote Fragmentations Occur under Matrix-Assisted Laser Desorption Ionization Post-Source Decompositions and Matrix-Assisted Laser Desorption Ionization Collisionally Activated Decompositions? M. Rosario M. Domingues, M. Grac¸a O. S.-Marques, Carla A. M. Vale, M. Grac¸a Neves, J. A. S. Cavaleiro, and A. J. Ferrer-Correia Department of Chemistry, University of Aveiro, Aveiro, Portugal Olga V. Nemirovskiy and Michael L. Gross Department of Chemistry, Washington University, St Louis, Missouri, USA The precursor ions of tetraphenylporphyrins that are substituted with fatty acids can be introduced into the gas phase by matrix-assisted laser desorption ionization (MALDI) and undergo post-source and collisionally activated decompositions (CAD) in a time-of-flight mass spectrometer. The goal of the research is to obtain a better understanding of post-source decompositions (PSD); specifically, we asked the question of whether ions undergoing PSD have sufficient energy to give charge-remote fragmentations along an alkyl chain. We chose the porphyrin macrocycle because we expected it to act as an inert “support,” allowing the molecule to be desorbed by MALDI and to be amenable to charge-remote fragmentation. MALDI-PSD and MALDI-CAD spectra are similar to high-energy CAD spectra and consid- erably more informative than low-energy CAD spectra, showing that charge-remote fragmen- tations of the fatty acid moieties do occur upon MALDI-PSD and MALDI-CAD. (J Am Soc Mass Spectrom 1999, 10, 217–223) © 1999 American Society for Mass Spectrometry ost-source decompositions (PSD) of ions pro- ever, observed different fragmentation pathways in duced by matrix-assisted laser desorption (MALDI) MALDI-PSD spectra when compared with those ob- Phas become a valuable structural tool for peptides served in LE-CAD and HE-CAD spectra.
    [Show full text]
  • Chemical Analysis in the Titan Environment
    • Magnetic Sector Mass Spectrometer • Quadrupole mass spectrometer • Quadrupole Ion Traps • Orthogonal Sampling Time of Flight Mass Spectrometer • Fourier Transform MS: Orbitrap Mass Spectrometer • Simulated Titan Chemistry (discharge and VUV) • Spectroscopic characteriza;on • Separa;on and analysis • Structural chemistry • Reac;vity (introduc;on of oxygen) Gas inlet Discharge Source UV Photolysis (ALS) Nier’s ‘mass spectrometer in a briefcase’, constructed in the mid-1960s, was used to convince NASA officials that it was possible to include such instrumentation on spacecraft. Miniature focal plane mass spectrometer with 1000-pixel modified-CCD detector array for direct ion measurement Mahadeva P. Sinha and Mark Wadsworth Rev. Sci. Instrum. 76, (2005); doi:10.1063/1.1840291 Schema'c of the focal plane mass spectrometer of Ma2auch–Herzog geometry Table I. MMS features and performance MMS Mass 395 g (as shown in the photograph) Dimensions 10 cm × 5 cm × 5 cm Ion source Thermionic Mass range 2–250 ResoluQon 330 (50% valley definiQon) SensiQvity 2 μA/Torr Photograph of the miniature mass spectrometer The spectrum measured by the transla'on of a single detector element along the focal plane. The peaks correspond to the residual gases in the vacuum chamber and the doubly charged ions arising from krypton gas introduced into the chamber. Rev. Sci. Instrum. 76, 025103 (2005) © 2005 American InsQtute of Physics A quadrupole mass filter consists of four parallel metal rods. Two opposite rods have an applied potenQal of (U+Vcos(wt)) and the other two rods have a potenQal of -(U+Vcos (wt)), where U is a dc voltage and Vcos(wt) is an ac voltage.
    [Show full text]
  • Atmospheric Pressure Chemical Ionization (APCI): Less Polar
    LC-MS Based Metabolomics AnalysingAnalysing thethe METABOLOMEMETABOLOME 1.1. MetaboliteMetabolite ExtractionExtraction 2.2. MetaboliteMetabolite detectiondetection (with(with oror withoutwithout separation)separation) 3.3. DataData analysisanalysis MetaboliteMetabolite DetectionDetection GC-MS: Naturally volatile or made volatile (any organic- flavors, sugars, lipids, acids) NMR – any compound containing hydrogen HP Liquid - Chromatography + detector Comon detectors- - UV-detector (phenolics) - MASS SPECTROMETER (MS) as detector (LC-MS) MetaboliteMetabolite DetectionDetection MASS SPECTROMETER (MS) as detector (LC-MS): Compounds that are not well characterized by other methods: Non volatile High molecular weight Too sensitive to heat to be analyzed by GC Your Result Sample LC/MS Sample Sample Efficient Separation Preparation Introduction Gradient (column) Data (computer) LC- MS Ions Ions Ionization UV Detection Separation MS Interface Spectra Today ComponentsComponents inin LCLC--MSMS Ion Ion Formation Sorting PeptiPeptiddee && ProteinProtein SeqSequuenciencinngg Compound ID APcI Analyzer Software LC Structure Elucidation ESI & Detector Quantitation Interface: Chemical Triple Quadrupole Atmospheric Results Separation Quadrupole -Time Of Flight Pressure Quadrupole - Ion-Trap Ionization FT-MS MassMass SpectrometerSpectrometer 1. Breaks up constituents into molecular ions and other fragments 2. The ions then pass through an electric and/or magnetic field that separates them according to their mass-to-charge ratio (m/z) 3. Measures masses MassMass SpectrometerSpectrometer 4. Universal detection method * compared to UV/VIS (PDA), fluorescence etc. * more specific than NMR 5. More sensitive for most compounds 6. Structural information on metabolite * fragmentation pattern * accurate mass 7. For both LC and GC TechnologyTechnology ofof LCLC--MSMS andand LCLC--MSMS--MSMS –– InterfacesInterfaces-- IonizationIonization (elimination(elimination ofof solventsolvent andand generationgeneration ofof gasgas--phasephase ions)ions) –– e.g.e.g.
    [Show full text]