Headspace-gas chromatography-mass spectrometry allows identification of chloropicrin in exposed soil, textile and hair

The volatile and toxic compound chloropicrin has re-emerged as a chemical warfare agent used to incapacitate soldiers in the field. Verification of its suspected use through analysis of incident-related samples is therefore essential. Here, we investigated the suitability of scalp hair, textiles and soil for post exposure identification of chloropicrin by using headspace-gas chromatography-mass spectrometry (HS-GC-MS). The sample materials were exposed to chloropicrin vapour at a dose equivalent to 70 mg/m 3 for 10 minutes using an in-house developed exposure chamber and analysed at defined intervals post exposure. Hair and textile samples were analysed with no further preparation, whereas the soil samples were prepared as slurries with NaCl-saturated water. The developed HS-GC-MS method enabled identification of chloropicrin at sub-ng levels. Chloropicrin residues were identified in three types of scalp hair, three textiles of different fibres and textures, and two different soil types following exposure. The time window for identification from vapor exposure to sampling and analysis varied from days for hair samples, to weeks for textiles, and months for soil samples. These results demonstrate the applicability of HS-GC-MS for identification of chloropicrin residues in vapour exposed samples, making it an important analytical tool for the verification of alleged use of chloropicrin as a chemical warfare agent.