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 1-6mg 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 2-4cm segments in some subject's hair. Even some of 4-6cm 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 2cm 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 11.93pg/mg, respectively. However, both the 4-6cm and the 6-8cm 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.