Headspace-trap gas chromatography–mass spectrometry for determination of sulphur mustard and related compounds in soil

Methods for trace determination of sulphur mustard (HD) and some related cyclic sulphur compounds in soil samples have been developed using headspace-trap in combination with gas chromatography–mass spectrometry (GC–MS). Two quite different types of soil were employed in the method optimisation (sandy loam and silty clay loam). Prior to analysis, water saturated with sodium chloride was added to the samples, at a water to soil ratio of 1:1. A detection limit of 3 ng/g was achieved for HD, while the cyclic sulphur compounds 1,4-thioxane, 1,3-dithiolane and 1,4-dithiane could be detected at 0.2–0.7 ng/g. The methods were validated in the concentration range from the limit of quantification (LOQ) to hundred times LOQ. The within assay precision at fifty times LOQ was 6.9–7.3% relative standard deviation (RSD) for determination of the cyclic sulphur compounds, and 15% RSD for determination of HD. Recoveries were in the range of 43–60% from the two soil types. As the technique requires very little sample preparation, the total time for sample handling and analysis was less than 1 h. The technique was successfully employed for the determination of cyclic sulphur compounds in a sediment sample from an old dumping site for chemical munitions, known to contain HD degradation products.