DOCSLIB.ORG

Mass Spectrometry in Proteomics

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mass Spectrometry in Proteomics Mass spectrometry in Proteomics Pierre-Alain Binz March 2004 WhatWhat isis aa massmass spectrum?spectrum? 1265.6038 100 MALDI-DE-RE-TOF MS 80 1394.7169 tryptic digest of BSA 60 1252.6472 1757.8374 870.4042 1299.6103 * % Intensity 40 * 1930.0053 1742.8780 * * 1410.7018 1787.7116 2062.0077 950.4584 2523.2021 20 * 1083.5082 2848.3 1778.0565 2285.1 2467.1695 848.2 1099.5 1859.9261 2065.0 2266.1 1364.7 1555.7 2501.3228 2016.0 2222.2043 2734.2 0 828.0 1263.2 1698.4 2133.6 2568.8 3004.0 Mass (m/z) Protein Identification using Mass Spectrometry protein from gel/ tryptic digestion & 1-DE, 2-DE, PVDF/LC fraction peptide extraction LC TYGGAAR EHICLLGK GANK PSTTGVEMFR unmodified and Mass spectrometry, modified peptides peptide mass fingerprints PMF identification MS Fragmentation Mass spectrometry, MS/MS identification peptide MS fragments HowHow areare massmass spectraspectra producedproduced ?? • Ions are produced in the source and are transferred into the mass analyser • They are separated according to their mass/charge ratio in the mass analyser (e.g. Quadrupole, Ion Trap, Time of Flight) • Ions of the various m/z values exit the analyser and are ‘counted’ by the detector Generic description of a mass spectrometer Atmosphere Vacuum System Sample Ionisation Mass Data Detector Inlet Method Analyser System IonizationIonization methodsmethods Analytes are ionized to be driven in the mass analyzer Electron impact (EI) Chemical Ionisation (CI) Fast atom bombardment (FAB) Field desorption (FD) Atmospheric Pressure Chemical Ionisation (APCI) ESI Electro-Spray Ionization MALDI Matrix Assisted Laser Desorption Ionization EI electron impact ionisation: beam of electrons through the gas-phase sample. Produces molecular ions or fragment ions. Typically 70eV. Sample heated. + Reproducible, structural information - sample must be volatile and stable, molecular ion often abscent mass range: < 1000Da CI: chemical ionisation: reagent gaz (methane, isobutane, or ammonia) ionized with electrons. High gaz pressure: (R = reagent, S = sample, e = electron, . = radical electron , H = hydrogen) R + e ---> R+. + 2e R+. + RH ---> RH+ + R. RH+ + S ---> SH+ + R Heated sample. + [M+H]+ often visible, less fragmentation than EI - sample must be volatile and stable, less structural info than EI mass range: < 1000Da DCI: Desorption CI : CI on a heated filament + rapid, simple - reproducibility mass range <1500Da NCI: negative-ion CI: electron capture; use of Methane to slow down electrons + efficient, sensitive; less fragmentation that EI, CI - not all molecule compatible, reproducibility mass range <1000Da FD: Field Desorption: sample deposited on filament gradually heated by electric field. Sample ionise by electron tunneling. Ions are M+ and [M+Na]+ + simple spectra, almost no background - sensitive to alkali, slow, volatile to desorb mass range <2000-3000Da FI: Field ionisation: sample introduced in gas phase (heaten or not), ionised by electron tunneling near the emitter. + simple spectra, almost no background - sample must be volatile mass range <1000Da FAB: fast atom bombardment: analyte in a liquid matrix (glycerol, etc.). Bombardment with fast atom beam (xenon at 6keV). Desorbtion of molecular ions, fragments and matrix clusters sample introduced liquid, or LC/MS + rapid, simple, good for variety of compounds, strong currents, high resolution - background, sample must be soluble in matrix mass range ~300-6000Da SIMS: soft ionisation: similar to FAB but with ion beam as gas (Ce+), allowing higher acceleration (energy) + idem FAB - idem FAB, target can get hotter, more maintenance mass range 300-13000Da ESI: electrospray ionisation: The sample solution is sprayed across a high potential difference (a few kilovolts) from a needle into an orifice in the interface. Heat and gas flows are used to desolvate the ions existing in the sample solution. ESI often produces multiply charged ions with the number of charges tending to increase as the molecular weight increases. High to low flow rates 1 ml/min to nl/min. + good for charged, polar or basic compounds, m/z ok for most MS, best for multiply charged ions, low background, controlled fragmentation, MS/MS compatible - complementary to APCI: not good for uncharged, non-basic, low-polarity compounds, low ion currents mass range <200’000Da APCI: atmospheric pressure CI: as in ESI, sample introduced in a high potential difference field. Uses a corona discharge for better ionisation of less polar molecules than in ESI. APCI and ESI are complementary MALDI: Matrix-Assisted Laser Desorption Ionization: analyte co-crystallised in matrix. The matrix chromophore absorbs and distribute the energy of a laser, produced a plasma, vaporates and ionize the sample. + rapid, convenient for molecular weight (singly charged ions mostly) - MS/MS difficult, almost not compatible with LC coupling <500’000Da ElectrosprayElectrospray IonizationIonization (ESI)(ESI) pump S S + + S S SH MH + + + + + + + S + + + + S MH SH MH +++ + 2+ + + S + + 2+ S + S SnH MH2 MH2 S + Smaller Coulomb explosion: Ions droplet droplet Clusters and ionic species Modif. From Alex Scherl Matrix Assisted Laser Desorption/Ionization MALDI UV or IR laser sample target Membrane, gel or metal grid Matrix Analytes Matrix Assisted Laser Desorption/Ionization MALDI MassMass AnalyzersAnalyzers Mass Spectrometers separate ions according to their mass-to- charge (m/z) ratios – Magnetic Sector – Quadrupole – Ion Trap – Time-of-flight – Hybrid- Sector/trap, Quad/TOF, etc. QuadrupoleQuadrupole massmass analyzeranalyzer + + + + RF + DC The quadrupole consists of • The ion is transmitted along the two pairs of parallel rods with quadrupole in a stable trajectory Rf field. applied DC and RF voltages. The ion does not have a stable Ions are scanned by varying trajectory and is ejected from the the DC/Rf quadrupole quadrupole. voltages. IonIon TrapTrap massmass analyzeranalyzer • Consists of ring electrode and two end caps • Principle very similar to quadrupole • Ions stored by RF & DC fields • Scanning field can eject ions of specific m/z • Advantages • - MS/MS/MS….. • - High sensitivity full scan MS/MS Time of Flight (TOF) mass analyzer High vacuum Ion source flight tube Detector time 1 Small ions are faster than heavy, and reach detector time 2 first time 3 Ion source High vacuum flight tube Detector Reflectron FTMS Ions moving at their cyclotron frequency can absorb RF energy at this same frequency. A pulse of RF excites the ions in the magnetic field. The ions re-emit the radiation, which is picked up by the reciever plates. The decay produces a free-induction decay signal that can be Fourier transformed to produce the emitted frequencies, and therefore the masses of the ions present. FTMSFTMS WhatWhat isis aa massmass spectrum?spectrum? 1265.6038 100 MALDI-DE-RE-TOF MS 80 1394.7169 tryptic digest of BSA 60 1252.6472 1757.8374 870.4042 1299.6103 * % Intensity 40 * 1930.0053 1742.8780 * * 1410.7018 1787.7116 2062.0077 950.4584 2523.2021 20 * 1083.5082 2848.3 1778.0565 2285.1 2467.1695 848.2 1099.5 1859.9261 2065.0 2266.1 1364.7 1555.7 2501.3228 2016.0 2222.2043 2734.2 0 828.0 1263.2 1698.4 2133.6 2568.8 3004.0 Mass (m/z) How does a peptide signal looks like? Low resolution High resolution Isotopic distribution Mass resolution 0.1% vs. 1 ppm Symbol Mass Abund. Symbol Mass Abund ------ ---------- ------ ------ ----------- ------- C(12) 12.000000 98.90 C(13) 13.003355 1.10 N(14) 14.003074 99.63 N(15) 15.000109 0.37 O(16) 15.994915 99.76 O(17) 16.999131 0.038 H(1) 1.007825 99.99 H(2) 2.014102 0.015 S(32) 31.972072 95.02 S(33) 32.971459 0.75 Isotopic distribution Mass resolution 10002000Half massFull width Mass resolution 1.0 FWHM 0.7 FWHM 0.5 FWHM 0.3 FWHM 0.2 FWHM 0.1 FWHM 524.3 100 95 90 85 80 75 Singly charged Ion: 70 65 Distance between Peak 60 and Isotop 1 amu 55 Abundance 50 45 = 1.0 amu = 1.0 amu Relative 40 _ 35 30 525.3 25 _ = 1.0 amu 20 15 10 526.2 5 0 520 521 522 523 524 525 526 527 528 529 m/z 262.6 100 95 90 85 80 75 Doubly charged Ion: 70 65 Distance between Peak and 60 Isotop 0.5 amu 55 Abundance 50 45 = 0.5 amu = 0.5 amu Relative 40 _ 35 30 25 20 263.1 15 _ = 0.5 amu 10 263.6 5 0 258 259 260 261 262 263 264 265 266 267 m/z Resolution: Example Peptide Mw 2129.64, Ion 4+ Intens. x105 533.46 Resolution 4 0.6 m/z 2 0 531 532 533 534 m/z Intens. x105 532.62 532.85 533.09 Resolution 1.0 533.33 0.2 m/z 0.5 533.61 0.0 531 532 533 534 m/z Multiply chargedmyoglobin ions from ESI (M 2-1.008) /M1-M2 = Z1 1060.5 100 M1 (Z 1 * M1)-(Z*1.008) = Mwt 90 1131.1 998.2 1211.9 M2 942.9 80 1305.0 70 893.3 60 848.6 1413.5 50 40 808.2 1541.9 30 771.5 20 1696.0 616.2 738.1 10 707.3 1310.9 1884.2 1428.7 1563.0 1820.8 1888.9 0 600 800 1000 1200 1400 1600 1800 2000 m/z Deconvoluted myoglobin spectrum 16951.0 100 90 80 70 60 50 40 30 20 10 15931.0 16104.0 16392.0 16582.0 16784.0 17088.017280.0 17562.0 17830.0 17995.0 0 16000 16200 16400 16600 16800 17000 17200 17400 17600 17800 18000 mass 9.9E+3 MALDI-DE-RE-TOF MS 100 90 tryptic digest of BSA 80 1265.6038 100 70 60 50 80 1394.7169 % Intensity 40 30 20 60 1252.6472 10 1757.8374 0 0 870.4042 1299.6103 1910.0 * 1918.8 1927.6 1936.4 1945.2 1954.0 % Intensity 40 * Mass (m/z) 1930.0053 1742.8780 * * 1410.7018 1787.7116 2062.0077 950.4584 2523.2021 20 * 1083.5082 2848.3 1778.0565 2285.1 2467.1695 848.2 1099.5 1859.9261 2065.0 2266.1 1364.7 1555.7 2501.3228 2016.0 2222.2043 2734.2 0 828.0 1263.2 1698.4 2133.6 2568.8 3004.0 Mass (m/z) Ion fragmentation with Mass Spectrometry Tandem MS or MS/MS One set of ions (one m/z value) is selected from a mixture of ions; These ions are fragmented; the fragments are measured.
Load more

Recommended publications
  • 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]
  • 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]
  • 1 Introduction of Mass Spectrometry and Ambient Ionization Techniques
    1 1 Introduction of Mass Spectrometry and Ambient Ionization Techniques Yiyang Dong, Jiahui Liu, and Tianyang Guo College of Life Science & Technology, Beijing University of Chemical Technology, No. 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China 1.1 Evolution of Analytical Chemistry and Its Challenges in the Twenty-First Century The Chemical Revolution began in the eighteenth century, with the work of French chemist Antoine Lavoisier (1743–1794) representing a fundamental watershed that separated the “modern chemistry” era from the “protochemistry” era (Figure 1.1). However, analytical chemistry, a subdiscipline of chemistry, is an ancient science and its metrological tools, basic applications, and analytical processes can be dated back to early recorded history [1]. In chronological spans covering ancient times, the middle ages, the era of the nineteenth century, and the three chemical revolutionary periods, analytical chemistry has successfully evolved from the verge of the nineteenth century to modern and contemporary times, characterized by its versatile traits and unprecedented challenges in the twenty-first century. Historically, analytical chemistry can be termed as the mother of chemistry, as the nature and the composition of materials are always needed to be iden- tified first for specific utilizations subsequently; therefore, the development of analytical chemistry has always been ahead of general chemistry [2]. During pre-Hellenistic times when chemistry did not exist as a science, various ana- lytical processes, for example, qualitative touchstone method and quantitative fire-assay or cupellation scheme have been in existence as routine quality control measures for the purpose of noble goods authentication and anti-counterfeiting practices. Because of the unavailability of archeological clues for origin tracing, the chemical balance and the weights, as stated in the earliest documents ever found, was supposed to have been used only by the Gods [3].
    [Show full text]
  • Mass Spectrometry Workshop Ionization Methods Three Major Info
    7/9/2018 Mass Spectrometry Workshop Ionization Methods Abraham Badu Assistant Professor Chemistry and Biochemistry July 9, 2018 OSU Three major info from MS • Molecular weight • Structural information via fragmentation • Isotope ratios 1 7/9/2018 Advances in Mass Spectrometry vacuum vacuum Ion Mass Ion Mass Detector Detector Source Analyzer Source Analyzer ‐ Electron Ionization (EI) ‐ Atmospheric Pressure Chemical Ionization (APCI) ‐ Chemical Ionization (CI) ‐ Electrospray Ionization (ESI) → For volale compounds → For non‐volatile liquid samples (≈1% of all compound) ‐ MALDI Ambient vacuum → For thermally Mass Detector unstable Ionization Analyte Sampling from their Native Analyzer solid samples Environment without Sample Methods Pre-treatment Some Sample Types Human Tissue Banknotes Whole Plant Drug Tablet Cooks et. al. Science 2004, 306, 471-473; Science 2006, 311, 1566 Badu-Tawiah et. al. Annu. Rev. Phys. Chem. 2013, 64, 481–505 Ionization Methods Neutral species → Charged species • Removal/addition of electron(s) – M + e- → (M+.)* + 2e- • electron ionization • Removal/addition of proton(s) – M + (Matrix)-H → MH+ + (Matrix)- • Chemical ionization (CI) • Atmospheric pressure CI (APCI) • Fast atom bombardment (FAB) • Electrospray/nanospray ionization (nESI) • Matrix assisted laser desorption/ionization (MALDI) • Desorption electrospray ionization (DESI) • Direct analysis in real time (DART) • Native spray 2 7/9/2018 Ion Sources: volatiles; non-volatile liquids; non-volatile solids EI ESI FAB MALDI Fast atom bombardment Electron Impact
    [Show full text]
  • Ionization Techniques – Part IV
    Ionization Techniques – Part IV CU- Boulder CHEM 5181 Mass Spectrometry & Chromatography Presented by Prof. Jose L. Jimenez MS Interpretation Lectures High Vacuum Sample Ion Mass Detector Recorder Inlet Source Analyzer Adapted from slides from Dr. Joel Kimmel, Fall 2007 1 Fast Atom Bombardment (FAB) and Secondary Ion Mass Spectrometry (SIMS) From Watson Desorption techniques. Analyze the ions emitted when a surface is irradiated with an energetic beam of neutrals (FAB) or ions (SIMS). 2 Producing Primary Beam: SIMS vs. FAB From de Hoffmann SIMS primary ions are Primary Beam of neutrals produced, e.g., as Cs atoms produced by ionizing and vaporize through a porous accelerating compound into tungsten plug. charge exchange collision with neutral. e.g.: From SIMS Tutorial: Ar+ + Ar → Ar+ + Ar http://www.eaglabs.com/en-US/references/tutorial/simstheo/ rapid slow slow rapid 3 Static SIMS • Low current (10-10 A cm2) of keV primary ions (Ar+, Cs+ ..) impact the solid analyte surface • Low probability of area being struck by multiple ions; less than 1/10 of atomic monolayer consumed • Primary ion beam focused to less than 1 um enables high resolution mapping – Often pulsed beam + TOFMS • Sensitive technique for the ID of organic molecules • Spectra show high abundance of protonated or cationized molecular ions. • Yields depend on substrate and primary beam; as high as 0.1 ions per incident ion. Elemental yields vary over many orders of magnitude. 4 FAB and liquid-SIMS • Sample is dissolved in non-volatile liquid matrix and bombarded with beam of neutrals (FAB) or ions • Shock wave ejects ions and molecules from solution.
    [Show full text]
  • Comparative Mass Spectrometric Analyses of Photofrin Oligomers By
    JOURNAL OF MASS SPECTROMETRY J. Mass Spectrom. 34, 661–669 (1999) Comparative Mass Spectrometric Analyses of Photofrin Oligomers by Fast Atom Bombardment Mass Spectrometry, UV and IR Matrix-assisted Laser Desorption/Ionization Mass Spectrometry, Electrospray Ionization Mass Spectrometry and Laser Desorption/Jet-cooling Photoionization Mass Spectrometry Marshall M. Siegel,1* Keiko Tabei,1 Rushung Tsao,1 Michael J. Pastel,1 Ravindra K. Pandey,2 Stefan Berkenkamp,3 Franz Hillenkamp3 and Mattanjah S. de Vries4 1 Wyeth-Ayerst Research, Lederle Laboratories, Pearl River, New York 10965, USA 2 Photodynamic Therapy Center, Department of Radiation Biology, Roswell Park Cancer Institute, Buffalo, New York 14263, USA 3 Institute for Medical Physics and Biophysics, University of Munster,¨ D-48149 Munster,¨ Germany 4 Department of Chemistry, The Hebrew University, Jerusalem 91904, Israel Photofrin (porfimer sodium) is a porphyrin derivative used in the treatment of a variety of cancers by photodynamic therapy. This oligomer complex and a variety of porphyrin monomers, dimers and trimers were analyzed with five different mass spectral ionization techniques: fast atom bombardment, UV and IR matrix- assisted laser desorption/ionization, electrospray ionization, and laser desorption/jet-cooling photoionization. All five approaches resulted in very similar oligomer distributions with an average oligomer length of 2.7 0.1 porphyrin units. In addition to the Photofrin analysis, this study provides a side-by-side comparison of the spectra for the five different mass spectrometric techniques. Copyright 1999 John Wiley & Sons, Ltd. KEYWORDS: photofrin; photodynamic therapy; oligomer distribution; mass spectrometry; fast atom bombardment; matrix-assisted laser desorption/ionization; electrospray ionization; laser desorption/jet cooling photoionization INTRODUCTION cancers of the lung and esophagus, in Canada for bladder and esophageal cancer and in Japan for the early stages of lung, esophageal, gastric and cervical cancers.
    [Show full text]
  • Components of a Mass Spectrometer
    Components of a Mass Spectrometer P. Babu, Ph. D. Centre for Cellular and Molecular Platforms Mass spectrometer Mass spectrometer is an instrument that measures the mass-to- charge ratio (m/z) values and their relative abundances of ions . Mass spectrum m/z – mass to charge ratio Base peak Isotopic peak Relative abundance Relative Molecular ion m/z Mass Mass unit 1 u = 1 Da = 1.660 540 × 10−27 kg. Molecular mass : Exact mass of an ion or molecule calculated using the mass of the most abundant isotope of each element Molar mass: Mass of one mole (6x1023 atoms or molecules) of a molecule/compound (i.e. isotope-averaged atomic mass for the constituent elements) MS principle e- D+ + R. M M +. - 2e D +. + N M+ -Molecular ion; D+ - Daughter ion or product ion Only charged species are detected in MS e.g. [M+nH]n+; [M-nH]n-; [M+Na]+ JJ Thamson’s 3rd Parabola Mass Spectrograph Components of a Mass Spectrometer . Sample Ion Source Analyzer Detector Data collector Inlet and processor HPLC Electron Ionization (EI) Sector Photoplate GC Chemical (CI) Quadrupole Faraday cup Syringe APCI TOF Electron multipliers (MCP) Plate APPI Orbitrap Solid-State Capillary Electrospray (ESI) FTICR Image current Fast Atom Bombardment (FAB) MALDI Sample Inlet HPLC GC Syringe Plate Capillary Ion source The role of the ion source is to create gas phase ions 1) Analyte atoms and molecules are transferred into gas phase 2) Ionization Hard (high energy) ionization and Soft (low energy) ionization Electron Ionization (EI) Chemical (CI) Spray Ionization (APCI, APPI, ESI) Desorption Ionization (FAB, MALDI, SALDI) Gas discharge ion sources (e.g.
    [Show full text]
  • Ionization Methods in Organic Mass Spectrometry
    Ionization Methods in Organic Mass Spectrometry Contents: . Introduction . Gas-Phase Ionization . Electron Ionization (EI) . Chemical Ionization (CI) . Desorption Chemical Ionization (DCI) . Negative-ion chemical ionization . Field Desorption and Ionization . Field Desorption (FD) . Field Ionization (FI) . Particle Bombardment . Fast Atom Bombardment (FAB) . Secondary Ion Mass Spectrometry (SIMS) . Atmospheric Pressure Ionization . Electrospray Ionization (ESI) . Atmospheric Pressure Chemical Ionization (APCI) . Laser Desorption . Matrix-Assisted Laser Desorption Ionization (MALDI) . Appendices . CI Reagent Gases . Direct Formation of Negative Ions . FAB matrices Introduction A mass spectrometer works by using magnetic and electric fields to exert forces on charged par- ticles (ions) in a vacuum. Therefore, a compound must be charged or ionized to be analyzed by a mass spectrometer. Furthermore, the ions must be introduced in the gas phase into the vacuum system of the mass spectrometer. This is easily done for gaseous or heat-volatile samples. How- ever, many (thermally labile) analytes decompose upon heating. These kinds of samples require either desorption or desolvation methods if they are to be analyzed by mass spectrometry. Al- though ionization and desorption/desolvation are usually separate processes, the term "ionization method" is commonly used to refer to both ionization and desorption (or desolvation) methods. The choice of ionization method depends on the nature of the sample and the type of information required from the analysis. So-called 'soft ionization' methods such as field desorption and elec- trospray ionization tend to produce mass spectra with little or no fragment-ion content. Gas-Phase Ionization These methods rely upon ionizing gas-phase samples. The samples are usually introduced through a heated batch inlet, heated direct insertion probe, or a gas chromatograph.
    [Show full text]
  • Ionization Techniques in Mass Spectrometry
    Pur y & ific tr at e io m n o Mass Spectrometry & Purification T r t e c c h e n p Medhe, Mass Spectrom Purif Tech 2018, 4:1 i S q u s s ISSN: 2469-9861e Techniques DOI: 10.4172/2469-9861.1000126 a s M Review Article Open Access Ionization Techniques in Mass Spectrometry: A Review Sharad Medhe* Department of Chemistry, Educational Institute, Dayalbagh, Agra-282005, India *Corresponding author: Sharad Medhe, Department of Chemistry, Educational Institute, Dayalbagh, Agra-282005, India, Tel: 0562 280 1545; E-mail: [email protected] Received date: May 08, 2018; Accepted date: June 14, 2018; Published date: June 23, 2018 Copyright: © 2018 Medhe S. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Mass Spectrometry- It is an analytical technique that generates charged particles in the form of ions from the substance to be analysed to measure its mass to charge ratio. Ion Source plays an important role for generation of charged ions which further travels through analyser and ends at detector. The production of intact molecular ions can be achieved under adequate experimental conditions, with minimal fragmentation known as soft ionization method. Neutral species either loss or gain of charge to generates ions. This paper covers an information about various type of mass ion Source (Electron impact, Chemical ionization and field ionization, Desorption-Field desorption, Electro spray ionization, matrix assisted desorption ionization, Plasma desorption) are in use for mass spectroscopy.
    [Show full text]
  • Fast Atom Bombardment and Electron Impact Mass Spectrometry Studies of Some Aryltin Compounds and Ferrocenes
    Fast Atom Bombardment and Electron Impact Mass Spectrometry Studies of Some Aryltin Compounds and Ferrocenes Yongchong Luo, B.Sc. (Hons.) A Thesis submitted to the Department of Chemistry in partial fulfillment of the requirements for the degree of Master of Science August 1993 Brock University St. Catharines, Ontario © Yongchong Luo .I. To my parents for their affection, encouragement and endurance during those hard times! .11. ABSTRACT Both El MS and FAB MS behavior of two groups of compounds, aryltin and ferrocene compounds, have been studied. For the aryltin compounds, the effect of substituent group position, substituent group type and ligand type on the El spectra have been explored in the El MS studies. The fragmentation mechanism has been investigated under El with linked scans, such as fragment ion scans(BJE), parent ion scans(B2JE) and constant neutral radical loss scans(B2(1-E)JE2). In the FAB MS studies, matrix optimization experiments have been carried out. The positive ion FAB MS studies focused on the effect of substituent group position, substituent group type and ligand type on the spectra. The fragmentation mechanisms of all the samples under positive ion FAB have been studied by means of the linked scans. The CA positive ion FAB fragmentation studies were also carried out for a typical sample. Negative ion FAB experiments of all the compounds have been done. And finally, the comparison of the El MS and FAB MS has been made. For ferrocenes, the studies concentrated on the fragmentation mechanism of each compound under El with linked scan techniques in the first field-free region and the applicability of positive/negative ion FAB MS to this group of compounds.
    [Show full text]
  • Best Practice Guide for Generating Mass Spectra
    for Best Practice Guide for Generating Mass Spectra Generating Mass Spectra Authors: Vicki Barwick John Langley Practice Guide Best Tony Mallet Bridget Stein Ken Webb BEST PRACTICE GUIDE FOR GENERATING MASS SPECTRA December 2006 Vicki Barwick, LGC John Langley, University of Southampton Tony Mallet, University of Greenwich Bridget Stein, EPSRC National Mass Spectrometry Service Centre Ken Webb, Consultant ISBN: 978-0-948926-24-2 © LGC Limited 2006 Preface This Guide was prepared as part of the Department of Trade and Industry’s VAM Programme which forms part of the UK National Measurement System. The Guide arose from discussions held at the VAM Mass Spectrometry Working Group and was prepared by LGC in collaboration with the members. In addition to major contributions by the authors, other members of the Working Group provided suggestions and comments. The idea for this work came about during preparation of an earlier guidance document* concerning accurate mass (“AccMass”) applications of mass spectrometry. It became clear that users of mass spectrometry instrumentation or services, including both specialists and research chemists, frequently have little understanding of the instrumentation or the meaning of the spectra they produce. Often, they will obtain or request an accurate mass determination for confirmation of identity on the basis of spectra which are meaningless or which could not possibly have originated from the target molecule. Discussion of this problem highlighted the changes which have taken place in teaching chemistry and analytical science and the rapid expansion in the application of mass spectrometry. The latter has been fuelled by a number of factors, including advances in the automation and performance of instrumentation and recent rapid growth in the use of mass spectrometry for the biosciences.
    [Show full text]
  • Mass Spectroscopy Reference Books: 1) Analytical Chemistry by Gary D
    Mass Spectroscopy Reference Books: 1) Analytical Chemistry by Gary D. Christian 2) Principles of instrumental Analysis by Skoog, Holler, Crouch 3) Fundamentals of Analytical Chemistry by Skoog 4) Basic Concepts of analytical Chemistry by S. M. Khopkar Principles of Mass Spectrometry Mass spectrometry is a sophisticated instrumental technique that produces, separates, and detects ions in the gas phase. The basic components of a mass spectrometer are shown in Figure. Samples are introduced into an ionization source through some type of inlet system. Depending on the phase and nature of the sample and the analytes, different ionization sources will be more or less optimal for producing ions. Analyte molecules are typically neutral and must be ionized. This can be accomplished in many ways. Analytes can be subjected to high-energy sources, such as electron bombardment, a laser, or an electrical discharge. Lower energy, or “softer,” ionization sources also exist, such as those encountered in atmospheric pressure ionization. We describe common ionization sources in the sections below. Ions are either created or rapidly transferred into a high-vacuum (low-pressure; 10-4 – 10-7 Torr) environment and can be separated based on their mass-to-charge (m/z) ratio through the application of electric and magnetic fields, in a variety of configurations. Different mass analyzers have different advantages, disadvantages, costs, and applications. Once the ions are separated, they are made to impinge on a detector, which converts the ion into an electrical signal that can be read by a data system. A variety of detectors exist, but some, such as the electron multiplier, are more common than others.
    [Show full text]