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.
^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.
^ abField, Frank H. (2002). "Chemical ionization mass spectrometry". Accounts of Chemical Research. 1 (2): 42–49. doi:10.1021/ar50002a002.
^Alex. G. Harrison (15 June 1992). Chemical Ionization Mass Spectrometry, Second Edition. CRC Press. pp. 1–. ISBN 978-0-8493-4254-7.
^ abHunt, 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.
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Chemicalionization (CI) is a soft ionization technique used in mass spectrometry. This was first introduced by Burnaby Munson and Frank H. Field in 1966...
Electron ionization is widely used in mass spectrometry, particularly for organic molecules. The gas phase reaction producing electron ionization is M +...
electron, and e− is the removed electron. Ionization energy is positive for neutral atoms, meaning that the ionization is an endothermic process. Roughly speaking...
threshold ionizationChemicalionization Electron ionizationIonization chamber – Instrument for detecting gaseous ionization, used in ionizing radiation...
atomic ions. The first molar ionization energy applies to the neutral atoms. The second, third, etc., molar ionization energy applies to the further...
Electron ionization (EI, formerly known as electron impact ionization and electron bombardment ionization) is an ionization method in which energetic electrons...
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...
electrospray ionization, and atmospheric-pressure chemicalionization. Both solid and liquid samples may be ionized with ambient ionization techniques....
Penning ionization is a form of chemi-ionization, an ionization process involving reactions between neutral atoms or molecules. The Penning effect is...
molecules to fragment when ionized. ESI is different from other ionization processes (e.g. matrix-assisted laser desorption/ionization, MALDI) since it may...
Electron capture ionization is the ionization of a gas phase atom or molecule by attachment of an electron to create an ion of the form A − {\displaystyle...
of organic compounds from electron ionization mass spectrometry. Organic chemists obtain mass spectra of chemical compounds as part of structure elucidation...
magnetic fields. There are several ionization methods: electron ionization, chemicalionization, electrospray ionization, fast atom bombardment, matrix assisted...
the chemical element, but is sometimes used to emphasize the change of numbers of nucleons in a nuclear reaction. If necessary, a state of ionization or...
molecules [ M + H ] + {\displaystyle [M+H]^{+}} . Chemicalionization was developed in the 1960s. Ionization of sample (analyte) is achieved by interaction...
samples are ionized have not been fully discovered, the nature of its ionization mechanism is similar to matrix-assisted laser desorption/ionization (MALDI)...
nanometers). Roughly, this corresponds to both the first ionization energy of oxygen, and the ionization energy of hydrogen, both about 14 eV. In some Environmental...
to produce analyte ions. Analytes with low ionization energy may be ionized directly. The DART ionization process can produce positive or negative ions...
with less net electric charge is called the ionization potential, or ionization energy. The nth ionization energy of an atom is the energy required to...
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