Elisa Wiborga,b, Helene Thorsen Rønninga, Hanne Røberg-Larsenb and Bent Tore Røena
a Norwegian Defence Research Establishment (FFI), Kjeller, Norway
b Section of Chemical Life Science, Department of Chemistry, University of Oslo, Norway
Email: elisa.wiborg@ffi.no
Chloropicrin (trichloronitromethane) is an industrial chemical primarily used in agriculture, which has also been used in chemical warfare due to its human toxicity. Such forbidden use has recently been actualised again through reports of alleged use of chloropicrin in the ongoing war in Ukraine. Since chemical warfare is strictly prohibited by international conventions, it is important to investigate these types of allegations, involving the analysis of samples from areas of suspected use.
When chloropicrin is released in an outdoor area a key question is which materials are best suited to identify chloropicrin residues, and for how long after an incident identification is possible. Soil is an omnipresent classic environmental sample worth investigating for this purpose. From exposed individuals, scalp hair and clothing textiles allow non-invasive sampling. In this study, we have investigated these three materials with respect to the identification time frame of chloropicrin after exposure.
To mimic a real exposure, we have used an in-house designed exposure chamber in a setup that allows a homogenous vapour exposure with a controlled dose of chloropicrin. Post exposure, the sample materials were stored in a fume hood until analysis at specific time intervals. A headspace-gas chromatography-mass spectrometry (GC-MS) method was developed for analysis of the chloropicrin residues. Headspace sampling allows the sample materials to be analysed directly, without further sample preparation. In addition, matrix interferences are minimised as only volatile compounds are injected into the GC.
With the exposure set-up and developed headspace-GC-MS method, we have investigated the sampling material potential of scalp hair (100 mg), three textiles of different fibres and textures (5 × 5 cm) and two different soil types, sandy and clay soil (3 g per sample), following an exposure dose of 70 mg/m3 chloropicrin for 10 minutes. Preliminary results show that the time frame for chloropicrin identification in scalp hair is around four days. In soil samples, it is longer, up to two to four weeks depending on soil humidity. While in textiles, it varies with fibre type and texture, from five to seven days and up to several weeks after exposure.