Chemical ionization

A schematic diagram of chemical ionization source

Chemical ionization (CI) is a soft ionization technique used in mass spectrometry.[1][2] This was first introduced by Burnaby Munson and Frank H. Field in 1966.[3] This technique is a branch of gaseous ion-molecule chemistry.[2] Reagent gas molecules (often methane or ammonia)[4] are ionized by electron ionization to form reagent ions, which subsequently react with analyte molecules in the gas phase to create analyte ions for analysis by mass spectrometry. Negative chemical ionization (NCI), charge-exchange chemical ionization, atmospheric-pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) are some of the common variants of the technique. CI mass spectrometry finds general application in the identification, structure elucidation and quantitation of organic compounds[5] as well as some utility in biochemical analysis.[5] Samples to be analyzed must be in vapour form, or else (in the case of liquids or solids), must be vapourized before introduction into the source.

  1. ^ Fales HM, Milne GW, Pisano JJ, Brewer HB, Blum MS, MacConnell JG, Brand J, Law N (1972). "Biological applications of electron ionization and chemical ionization mass spectrometry". Recent Prog. Horm. Res. 28: 591–626. PMID 4569234.
  2. ^ a b Field, Frank H. (2002). "Chemical ionization mass spectrometry". Accounts of Chemical Research. 1 (2): 42–49. doi:10.1021/ar50002a002.
  3. ^ Alex. G. Harrison (15 June 1992). Chemical Ionization Mass Spectrometry, Second Edition. CRC Press. pp. 1–. ISBN 978-0-8493-4254-7.
  4. ^ "Mass Spectrometry Facility | CI". www.chm.bris.ac.uk. Retrieved 2022-04-30.
  5. ^ a b Hunt, Donald F.; McEwen, Charles N.; Harvey, T. Michael. (2002). "Positive and negative chemical ionization mass spectrometry using a Townsend discharge ion source". Analytical Chemistry. 47 (11): 1730–1734. doi:10.1021/ac60361a011.