Robert J. Cotter

Robert J. Cotter (July 15, 1943 – November 12, 2012 ) was an American chemist and mass spectrometrist. His research contributed to many early advances in the field of time-of-flight mass spectrometry. From 1998 to 2000 he was president of the American Society for Mass Spectrometry.[2] Cotter was also a co-investigator on the Mars Organic Molecule Analyzer (MOMA) project, developing a miniaturized, low power consumption ion trap/time-of-flight mass spectrometer that was to be deployed with the ExoMars rover.[3]

Robert J. Cotter
Born(1943-07-15)July 15, 1943
Washington, DC, United States
DiedNovember 12, 2012(2012-11-12) (aged 69)[1]
Baltimore, Maryland, United States
NationalityUnited States
Alma materCollege of the Holy Cross
Johns Hopkins University
Known forTime-of-flight mass spectrometry
Spouse(s)Catherine Clarke Fenselau
AwardsField and Franklin Award (2011)
ASMS Distinguished Contribution in Mass Spectrometry Award (2011)
Scientific career
FieldsMass spectrometry
InstitutionsTowson University, Gettysburg College, Johns Hopkins University
Doctoral advisorW.S. Koski

Early life

Cotter was raised in Abington, Massachusetts and was the oldest of seven children. After graduating from Boston College High School in 1961, he attended the College of the Holy Cross in Worcester, Massachusetts. After receiving a B.S. degree in 1965, he studied under W.S. Koski at Johns Hopkins University. He received his PhD in 1972 and joined the faculty of Towson University and Gettysburg College.[1]

Academic research career

From 1978 until his death in 2012, Robert Cotter was a member of the faculty at Johns Hopkins University in the departments of Pharmacology and Molecular Sciences and Biophysics and Biophysical Chemistry.[4]

Curved-field reflectron

To increase the mass resolution in time-of-flight mass spectrometry, a reflectron is often employed. Traditional, single-stage or linear reflectrons suffered from a lack of sensitivity and resolving power when ion velocities (and thus kinetic energies were not equal. In MALDI mass spectrometry, metastable ions generated spontaneously after ionization (post-source decay) exhibit a wide spectrum of kinetic energies.[5] This is also known to occur during collision-induced dissociation.[6] In 1993, Cotter's research group discovered that, using a non-linear electric field, the spread of ion kinetic energies could be compensated, increasing the resolution of time-of-flight mass spectrometers and forming the basis for many modern TOF/TOF mass spectrometers.[7]

Ionization and biological mass spectrometry

While he is primarily known for his contributions to the field of time-of-flight mass spectrometry,[8] his research in the development and application of new ionization techniques for complex biomolecules. These include thermal desorption,[9] laser desorption,[10] fast atom bombardment,[11] thermospray[12] and plasma desorption.[13]

His research into ionization sources also enabled many other discoveries in biomedical sciences.[6] In 1993, he was part of the research team responsible for implicating the 42 amino acid form of the protein Aβ in the pathology of Alzheimer's disease.[14]

Mars organic molecule analyzer

The Mars Organic Molecule Analyzer (MOMA) project is part of a collaboration to search for potential signatures of Martian life. Cotter was a deputy principal investigator and responsible for the design and development of a low-power, ion trap-time-of-flight mass spectrometer to be deployed with the ESA ExoMars rover.[3] However, in February 2012, NASA cancelled its participation in the rover and defunded projects related to it.[15] By November 2012 NASA reestablished the funding for the US part of MOMA.[16]


  1. Siegel, Andrea (November 18, 2012). "Robert J. Cotter, Johns Hopkins medical school professor". Baltimore Sun. Retrieved November 21, 2012.
  2. Past presidents, ASMS, retrieved 2010-11-17.
  3. Cotter RJ, Swatkoski S, Becker L, Evans-Nguyen T (2010). "Time-of-flights and traps: from the Histone Code to Mars". Eur J Mass Spectrom. 16 (3): 331–340. doi:10.1255/ejms.1082. PMC 3401572. PMID 20530839.
  4. "Robert Cotter". Archived from the original on November 17, 2012. Retrieved November 21, 2012.
  5. Spengler B, Kirsch D, Kaufmann R (1991). "Metastable Decay of Peptides and Proteins in Matrix-assisted Laser-desorption Mass Spectrometry". Rapid Comm. Mass Spec. 5 (4): 198–202. doi:10.1002/rcm.1290050412.
  6. Cotter, Robert J. (1997). Time-of-Flight Mass Spectrometry: Instrumentation and Applications in Biological Research. Washington, DC: American Chemical Society. ISBN 978-0841234741.
  7. Cornish T, Cotter, RJ (1993). "A curved-field reflectron for improved energy focusing of product ions in time-of-flight mass spectrometry". Rapid Comm. Mass Spec. 7 (11): 1037–1040. doi:10.1002/rcm.1290071114. PMID 8280914.CS1 maint: multiple names: authors list (link)
  8. Cotter, RJ (1992). "Time-of-Flight Mass-Spectrometry for the Structural-Analysis of Biological Molecules". Anal. Chem. 64 (21): A1027–A1039. doi:10.1021/ac00045a002.
  9. Cotter, RJ & Yergey, AL (1981). "Thermally Produced Ions in Desorption Mass Spectrometry". Anal. Chem. 53 (8): 1306–1307. doi:10.1021/ac00231a039.
  10. Cotter, RJ (1980). "Laser Desorption Chemical Ionization Mass-Spectrometry". Anal. Chem. 52 (11): 1767–1770. doi:10.1021/ac50061a055.
  11. Fenselau, C, Liberato, DJ, Yergey, JA, Cotter, RJ, Yergey, AL (1984). "Comparison of Thermospray and Fast Atom Bombardment Mass-spectrometry as Solution-Dependent Ionization Techniques". Anal. Chem. 56 (14): 2759–2762. doi:10.1021/ac00278a030.CS1 maint: multiple names: authors list (link)
  12. Simpson RC, Fenselau CC, Hardy MR, Townsend RR, Lee YC, Cotter RJ (1990). "Adaptation of a Thermospray Liquid-Chromatography Mass-Spectrometry Interface For Use with Alkaline Anion-Exchange Liquid-Chromatography of Carbohydrates". Anal. Chem. 62 (3): 248–252. doi:10.1021/ac00202a005.
  13. Alai M, Demirev P, Fenselau C, Cotter, RJ (1986). "Glutathione as a Matrix For Plasma Desorption Mass-Spectrometry of Large Peptides". Anal. Chem. 58 (7): 1303–1307. doi:10.1021/ac00298a008.CS1 maint: multiple names: authors list (link)
  14. Roher, AE, Lowenson, JD Clarke, S, Woods, AS, Cotter, RJ, Gowing, E, Ball, MJ (1993). "Beta-Amyloid-(1-42) is a Major Component of Cerebrovascular Amyloid Deposits – Implications for the pathology of Alzheimer-Disease". Proc. Natl. Acad. Sci. USA. 90 (22): 10836–10840. doi:10.1073/pnas.90.22.10836. PMC 47873. PMID 8248178.CS1 maint: multiple names: authors list (link)
  15. "Tracing the Big Picture of Mars' Atmosphere". Retrieved November 21, 2012.
  16. STEPHEN CLARK (November 21, 2012). "European states accept Russia as ExoMars partner". SPACEFLIGHT NOW. Cite journal requires |journal= (help)
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