Analysis of chemical warfare agents: II. Use of thiols and statistical experimental design for the trace level determination of vesicant compounds in air samples

Thermal desorption with gas chromatography–mass spectrometry (TD–GC–MS) remains the technique of choice for analysis of trace concentrations of analytes in air samples. This paper describes the development and application of a method for analysing the vesicant compounds sulfur mustard and Lewisites I–III. 3,4-Dimercaptotoluene and butanethiol were used to spike sorbent tubes and vesicant vapours sampled; Lewisite I and II reacted with the thiols while sulfur mustard and Lewisite III did not. Statistical experimental design was used to optimise thermal desorption parameters and the optimum method used to determine vesicant compounds in headspace samples taken from a decontamination trial. 3,4-Dimercaptotoluene reacted with Lewisites I and II to give a common derivative with a limit of detection (LOD) of 260 μg m−3, while the butanethiol gave distinct derivatives with limits of detection around 30 μg m−3.