A new ppb-gas analyzer by means of GC-ion mobility spectrometry (GC-IMS)

Abstract

IMS-detectors are using beta-sources like tritium or nickel-63. This detection principle uses fast ion-molecular reactions between air cluster ions, produced by beta ionization and the analyte. The system works at normal pressure, the very high sensitivity and selectivity is used widely in industry, research, medicine and environmental control. In the last few years especially, small tritium sources were reduced to a level of some 50 MBq, which is 20 times less than the exemption levels for these sources. One of the handicaps of that technology is the problem of cross sensitivities. To overcome these problems a special GC-column of 1 m length has been included into the gas inlet and mixtures of compounds get separated by their retention times before entering the drift sensor. By means of that method a new analytical quality of IMS is arrived. The application of these analytical devices got a spin off in the last year. The main applications being discussed are as follows: (1) anti terror systems in buildings and facilities, (2) working place monitoring in chemical industry, (3) microelectronics: HF, HCl, Cl₂, NMP, NH₃, NO₂, SO₂, (4) environment: NH₃, HCN, HCl, CH₂O, organic compounds, SO₂, NO₂, (5) gas and petrol: gas-carottage, H₂S, mercaptans, (6) household, furniture: solvents, clue, organic vapour from furniture, and (7) health care: diagnostics of various diseases.