Traceability of etomidate and its analogs in biological samples using “specific” metabolites

-butomidate were not detected in the actual 83 hair and 4 urine samples tested; ETO and isopropoxate were the two main drugs detected in hair samples; and CF3-etomidate, a novel alternative, was detected in hair at a higher rate than metomidate. In addition, 47 hair samples showed a single parent substance, and 35 samples contained two or more drugs, indicating the possibility of mixed use of ETO and its analogues. The biomarkers of metomidate in both urine and hair are hydroxylated metabolites on the benzene ring; the biomarkers of isopropoxate undergo a hydroxylation reaction on the benzene ring (hair) and cleavage of the C-N bond between the imidazole ring and alkyl group (urine); the metabolic product of the hydroxylation reaction on alkyl groups is a biomarker of butomidate. In this study, the metabolite differences of seven ETO analogs were compared for the first time in order to infer the parent compounds based on biomarkers. Meanwhile, based on the existing knowledge of the metabolism of the seven known substances in this experiment, it is possible to make a preliminary prediction of emerging ETO analogs in order to improve the understanding of early warning systems and the timely updating of monitoring techniques.