Taking the advantages of the chemical conversion of analytes through chemical reactions either in the solution or gas phase, very often an instrumental analytical problem can be addressed in a completely different way. This is at large due to the involvement of the chemical resolution in instrumental analysis. This review is focused specifically on contributions of chemical reactions to the development of novel instrumental analytical techniques in chromatography-mass spectrometry in the past two decades. It covers first the commercial instrumentations based on chemical reactions of analytes in the gas phase such as chemical ionization in gas chromatography- mass spectrometry (GC-MS), atmospheric pressure chemical ionization in liquid chromatography-mass spectrometry (LC-MS), proton- transfer reaction GC-MS for volatile organic compounds, and chemical reaction interface-mass spectrometry as a universal detector for GC, LC and size-exclusion chromatography (SEC) separation. Additionally, the recent development of a novel technique based on selective reactions of chemical noise ions with chosen neutral reagents for the reduction of c hemical background noise in LC-MS trace analysis is also reviewed. The contribution of ion-molecule reactions to each instrumentation and their applications compared to other conventional techniques will be discussed.
Keywords: Liquid chromatography-mass spectrometry, gas chromatography-mass spectrometry, ion-molecule reactions, chemical ionization, atmospheric pressure chemical ionization, chemical reaction interface, proton-transfer reaction, chemical noise reduction, GC-MS, LC-MS, size-exclusion chromatography, SEC, high performance liquid chromatography, HPLC, electron capture detectors, ECD, ion specific electrode, ISE, calorimetry, ion chromatography, capillary electrophoresis, protonated methane ion, CH5, ethylene diamine, di-methylamine, nitrous oxide-methane, methyl nitrite-methane, methylene chloride-methane, dichlorodifluoromethane, isobutane-methylene dichloride-Cl2-O2, APCI, Proton-transfer-reaction mass spectrometry, PTR-MS, volatile organic com-pounds, VOCs, Chemical reaction interface mass spectrometry, CRIMS, inductively coupled plasma-mass spectrometry, ICP-MS, dimethyl disulfide, CH3SSCH3, selected ion monitoring, SIM, multiple reaction monitoring, MRM