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Chemical Ionization—A Mass‐Spectrometric Analytical Procedure of Rapidly Increasing Importance
Author(s) -
Richter Wilhelm J.,
Schwarz Helmut
Publication year - 1978
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.197804241
Subject(s) - electron ionization , chemical ionization , ionization , ion , fragmentation (computing) , chemistry , mass spectrometry , reagent , molecule , mass spectrum , analytical chemistry (journal) , ion source , direct electron ionization liquid chromatography–mass spectrometry interface , substrate (aquarium) , ambient ionization , chemical reaction , chromatography , organic chemistry , oceanography , computer science , geology , operating system
The mode of ionization of a molecule has a strong influence on its behavior in the mass spectrometer and thus on the information that can be obtained from its mass spectrum. In chemical ionization a reagent gas, e.g. methane, is first ionized by electron impact. The ions formed in ion‐molecule reactions, in particular [CH 5 ] + , [C 2 H 5 ] + , and [C 3 H 5 ] + , then react “chemically” with the substrate M in fast acid/base type reactions to form ions of the type [MH] + , [M(C 2 H 5 )] + , etc. , which subsequently fragment to various extents. Alternatively, chemical ionization can be effected by charge exchange, in that ions of a reagent gas, e.g. [He] +• , react with the substrate M to form molecular ions [M] +· . Chemical ionization can thus be conducted in a more or less mild fashion and the extent of the fragmentation can be controlled over a very wide range.