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Electrospray ionization (ESI) is a technique used in mass spectrometry to produce ions using an electrospray in which a high voltage is applied to a liquid to create an aerosol. It is especially useful in producing ions from macromolecules because it overcomes the propensity of these molecules to fragment when ionized. ESI is different from other ionization processes since it may produce multiple-charged ions, effectively extending the mass range of the analyser to accommodate the kDa-MDa orders of magnitude observed in proteins and their associated polypeptide fragments.
In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy-absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of biomolecules and various organic molecules, which tend to be fragile and fragment when ionized by more conventional ionization methods. It is similar in character to electrospray ionization (ESI) in that both techniques are relatively soft ways of obtaining ions of large molecules in the gas phase, though MALDI typically produces far fewer multi-charged ions.
Electron-capture dissociation (ECD) is a method of fragmenting gas-phase ions for structure elucidation of peptides and proteins in tandem mass spectrometry. It is one of the most widely used techniques for activation and dissociation of mass selected precursor ion in MS/MS. It involves the direct introduction of low-energy electrons to trapped gas-phase ions.
Ammonium acetate, also known as spirit of Mindererus in aqueous solution, is a chemical compound with the formula NH4CH3CO2. It is a white, hygroscopic solid and can be derived from the reaction of ammonia and acetic acid. It is available commercially.
Gas phase ion chemistry is a field of science encompassed within both chemistry and physics. It is the science that studies ions and molecules in the gas phase, most often enabled by some form of mass spectrometry. By far the most important applications for this science is in studying the thermodynamics and kinetics of reactions. For example, one application is in studying the thermodynamics of the solvation of ions. Ions with small solvation spheres of 1, 2, 3... solvent molecules can be studied in the gas phase and then extrapolated to bulk solution.
The history of mass spectrometry has its roots in physical and chemical studies regarding the nature of matter. The study of gas discharges in the mid 19th century led to the discovery of anode and cathode rays, which turned out to be positive ions and electrons. Improved capabilities in the separation of these positive ions enabled the discovery of stable isotopes of the elements. The first such discovery was with the element neon, which was shown by mass spectrometry to have at least two stable isotopes: 20Ne and 22Ne. Mass spectrometers were used in the Manhattan Project for the separation of isotopes of uranium necessary to create the atomic bomb.
The McLafferty rearrangement is a reaction observed in mass spectrometry during the fragmentation or dissociation of organic molecules. It is sometimes found that a molecule containing a keto-group undergoes β-cleavage, with the gain of the γ-hydrogen atom, as first reported by Anthony Nicholson working in the Division of Chemical Physics at the CSIRO in Australia. This rearrangement may take place by a radical or ionic mechanism. This reaction occurs secondary to the Cormas-Grisius electrophilic benzene addition reaction, a multi-step benzene-derivative reaction. The Cormas-Grisius electrophilic benzene addition reaction's validity is highly contested by scholars in the field, and its practical usage has yet to be elucidated.
Soft laser desorption (SLD) is laser desorption of large molecules that results in ionization without fragmentation. "Soft" in the context of ion formation means forming ions without breaking chemical bonds. "Hard" ionization is the formation of ions with the breaking of bonds and the formation of fragment ions.
Robert Graham Cooks is the Henry Bohn Hass Distinguished Professor of Chemistry in the Aston Laboratories for Mass Spectrometry at Purdue University. He is an ISI Highly Cited Chemist, with over 1,000 publications and an H-index of 150.
Fred Warren McLafferty was an American chemist known for his work in mass spectrometry. He is best known for the McLafferty rearrangement reaction that was observed with mass spectrometry. With Roland Gohlke, he pioneered the technique of gas chromatography–mass spectrometry. He is also known for electron-capture dissociation, a method of fragmenting gas-phase ions.
Christie G. Enke is a United States academic chemist who made pioneering contributions to the field of analytical chemistry.
David E. Clemmer is an analytical chemist and the Distinguished Professor and Robert and Marjorie Mann Chair of Chemistry at Indiana University in Bloomington, Indiana, where he leads the Clemmer Group. Clemmer develops new scientific instruments for ion mobility mass spectrometry (IMS/MS), including the first instrument for nested ion-mobility time-of-flight mass spectrometry. He has received a number of awards, including the Biemann Medal in 2006 "for his pioneering contributions to the integration of ion mobility separations with a variety of mass spectrometry technologies."
Michael L. Gross is Professor of Chemistry, Medicine, and Immunology, at Washington University in St. Louis. He was formerly Professor of Chemistry at the University of Nebraska-Lincoln from 1968–1994. He is recognized for his contributions to the field of mass spectrometry and ion chemistry. He is credited with the discovery of distonic ions, chemical species containing a radical and an ionic site on different atoms of the same molecule.
Ambient ionization is a form of ionization in which ions are formed in an ion source outside the mass spectrometer without sample preparation or separation. Ions can be formed by extraction into charged electrospray droplets, thermally desorbed and ionized by chemical ionization, or laser desorbed or ablated and post-ionized before they enter the mass spectrometer.
Renato Zenobi is a Swiss chemist. He is Professor of Chemistry at ETH Zurich. Throughout his career, Zenobi has contributed to the field of analytical chemistry.
Catherine Clarke Fenselau is an American scientist who was the first trained mass spectrometrist on the faculty of an American medical school; she joined Johns Hopkins School of Medicine in 1968. She specializes in biomedical applications of mass spectrometry. She has been recognized as an outstanding scientist in the field of bioanalytical chemistry because of her work using mass spectrometry to study biomolecules.
Atmospheric pressure photoionization (APPI) is a soft ionization method used in mass spectrometry (MS) usually coupled to liquid chromatography (LC). Molecules are ionized using a vacuum ultraviolet (VUV) light source operating at atmospheric pressure, either by direct absorption followed by electron ejection or through ionization of a dopant molecule that leads to chemical ionization of target molecules. The sample is usually a solvent spray that is vaporized by nebulization and heat. The benefit of APPI is that it ionizes molecules across a broad range of polarity and is particularly useful for ionization of low polarity molecules for which other popular ionization methods such as electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) are less suitable. It is also less prone to ion suppression and matrix effects compared to ESI and APCI and typically has a wide linear dynamic range. The application of APPI with LC/MS is commonly used for analysis of petroleum compounds, pesticides, steroids, and drug metabolites lacking polar functional groups and is being extensively deployed for ambient ionization particularly for explosives detection in security applications.
Richard M. Caprioli is an American chemist known for his contributions to mass spectrometry imaging.
Hilkka Inkeri Kenttämaa is a researcher in organic and bioorganic mass spectrometry, and the Frank Brown Endowed Distinguished Professor of Chemistry at Purdue University. She is a pioneer in distonic radical cation research and laser-induced acoustic desorption.
References
- 1 2 "Michael T. Bowers" . Retrieved 23 September 2020.
- ↑ "APS Fellow Archive". APS. Retrieved 23 September 2020.
- ↑ Bierbaum VM (2005). "Focus in honor of Michael T. Bowers, recipient of the 2004 award for distinguished contribution in mass spectrometry". J. Am. Soc. Mass Spectrom. 16 (7): 983. Bibcode:2005JASMS..16..983B. doi: 10.1016/j.jasms.2005.04.015 . PMID 15914024.
- ↑ Bowers M (2005). "A personal retrospective of the early years". J. Am. Soc. Mass Spectrom. 16 (7): 984–8. Bibcode:2005JASMS..16..984B. doi: 10.1016/j.jasms.2005.04.016 . PMID 15914023.
