Fragmentation of molecular ions in differential mobility spectrometry as a method for identification of chemical warfare agents

Abstract

The subject of the work is the use of differential mobility spectrometry (DMS) for the detection of chemical warfare agents (CWA). Studies were performed for mustard gas, i.e., bis(2-chloroethyl)sulfide (HD), sarin, i.e., O-isopropyl methylphosphonofluoridate (GB) and methyl salicylate (MS) used as test compounds. Measurements were conducted with two ceramic DMS analyzers of different constructions allowing the generation of an electric field with an intensity of more than 120Td. Detector signals were measured for positive and negative modes of operation in a temperature range from 0 to 80°C. Fragmentations of ions containing analyte molecules were observed for all tested compounds. The effective temperatures of fragmentation estimated on the basis of dispersion plots were equal from about 148°C for GB to 178°C for MS. It was found that values of separation voltage (SV) and compensation voltage (CV) at which the fragmentation of sample ions is observed may be the parameters improving the certainty of detection for different analytes. The DMS analyzers enabling the observation of ion fragmentation can be successfully used for effective CWA detection.