Segmental hair analysis using liquid chromatography–tandem mass spectrometry after a single dose of benzodiazepines

In China, benzodiazepines are the most frequently observed compounds in cases of drug-facilitated crime. Sensitive, specific, and reproducible methods for the quantitative determination of 18 benzodiazepines in hair have been developed using LC–MS/MS. Fourteen volunteers had ingested a single 1–6 mg estazolam tablet. Hair was collected 1 month after administration. All the proximal segments were positive for estazolam. With increased dosage, estazolam can be detected in the 2–4 cm segments in some subject's hair. Even some of 4–6 cm segments were positive. Hair analysis was applied to two authentic criminal cases. Full-length hair samples collected 5 weeks after the offense were cut into segments of 2 cm from the root, analyzed and quantified. The clonazepam concentrations measured in the first two segments for V#1 and V#2 were 15.47 and 11.93 pg/mg, respectively. However, both the 4–6 cm and the 6–8 cm segment of V1# remained positive, while those of V#2 were negative. It needs more substantial guidelines to use segmental hair analysis in drug-facilitated crime.