Detection of Chemically Hazardous Substances by Ion Mobility Spectrometry

A comparison of chemical detectors based on ion mobility spectrometry used by rapid response services for the rapid detection and identification of a wide range of chemically hazardous substances has been carried out. The physical foundations of the registration method, the method of mathematical processing of spectra and determination of the ionic mobility of substances are presented. A procedure for the preparation of test samples of vapors of volatile organic compounds in a wide range of concentrations has been developed. To identify the compounds, domestic devices were used – the Kerber-T ion drift detector and the Segment stationary automatic gas detector. Their comparison in sensitivity and detection range in the identification of compounds was carried out. The research was conducted on a set of substances standardized to ensure safety in terrorist attacks. As a result of the work, ion mobility spectra for bromocyanum, carbon disulfide, and chloroacetone were obtained. The values of ionic mobility were determined, the dependences of the spectra of these compounds on the concentration in the air were investigated, as well as the limits of detection of substances. Possible mechanisms for the formation of the observed ion mobility spectra are proposed in accordance with the ionization characteristics of bromocyanate, carbon disulfide, and chloroacetone. Schemes of possible formation of monomeric and dimeric ions of compounds are shown. The generalized results of experimental studies, the peculiarities of the identification of compounds, taking into account the type of spectra, concentrations of substances and measurement conditions, are obtained.