Fast high-resolution mass spectrometry in the triage investigation of poisonings by pesticides in unusual samples - a case study

Pesticides play a pivotal role in the development of agriculture, as they prevent the proliferation of pests and disease vectors in crops. However, there are several controversies regarding their use, as some are highly toxic to humans and frequently used illegally as chemical weapons. In this study, two criminal cases of alleged pesticide poisoning were investigated to establish whether there was an attempted murder (Case 1) and to determine the cause of death (Case 2). A sample of gastric content (Case 1) was extracted with QuEChERS salts, whereas the samples of Case 2, which include hair, nail and an aliquot of gastric contents were analysed without previous extraction. All samples (extracted and unextracted) from Case 1 were analysed by ESI and DART ionization using an Orbitrap mass spectrometer. Case 2 samples were analysed using only DART-HRMS, due to the limited sample available. The ESI-HRMS technique did not detect pesticides in the unextracted gastric content. However, terbufos and terbufos sulfoxide were identified in the gastric content extract. On the other hand, DART-HRMS confirmed the presence of terbufos sulfoxide and carbofuran in the unextracted gastric content and detected carbofuran in the nail sample. The hair sample exhibit no positive results for any exogenous substance. The results suggest that both techniques efficiently provide insight for further confirmatory analysis in the elucidation of forensic cases. However, the DART source seems to be an approach that circumvents the need for pre-treatment of solid and liquid samples.