Single-hair analysis of zolpidem on the supposition of its single administration in drug-facilitated crimes

Little information is available on the amounts of hypnotics incorporated into hair after a single administration and about effective analytical procedures to document cases like drug-facilitated sexual assaults. To obtain basic information, single-hair specimens from a volunteer who took a single dose of 10-mg zolpidem (ZP) were analyzed by a newly established liquid chromatography–tandem mass spectrometry procedure, using a one-pot pulverization extraction method. The detection limit of ZP was 50 fg/2-cm single hair, and ZP in each segment was determined for the single black hair specimens (n = 15). ZP was detectable in 14 hairs (positive for all the proximal 0–2 cm segments, negative for all 2–4 cm segments), but was not detected in a single hair (probably in the telogen stage). The amounts of ZP detected in each positive 2-cm segment of single hair ranged from 27 to 63 pg (average 43 pg). The estimated total incorporation of ZP in the scalp hair (black hair ~110,000 strands) was about 4.7 μg, which corresponds to about 0.06 % of the single 10-mg dose (8.03 mg as free ZP). In addition, the direct detection of single-dose ZP incorporated in hair and its imaging were successfully achieved by matrix-assisted laser desorption ionization-mass spectrometry. It is suggested that a combination of these methodologies will provide the highest-level evidence to document such exposure to a hypnotic drug.