High-performance liquid chromatographic-mass spectrometric determination of methamphetamine and amphetamine enantiomers, desmethylselegiline and selegiline, in hair samples of long-term methamphetamine abusers or selegiline users

We devised a highly sensitive method for simultaneously determining methamphetamine (MA) and amphetamine (AP) enantiomers, desmethylselegiline (DMSG) and selegiline (SG), in human hair using a derivatization technique and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). MA and AP enantiomers and DMSG were effectively converted to trifluoroacetic acid (TFA) derivatives, and the sensitivity of MA and DMSG increased five times over compared with that of free bases. The TFA derivatives of each compound were stable within one week in a stock solution of methanol or for 24 h in the HPLC mobile phase (mixture of methanol and ammonium formate buffer). Each compound was well separated, and calibration curves were linear in the concentration range 0.04-40 ng/mg for MA enantiomers, SG and DMSG, and 0.2-40 ng/mg for AP enantiomers. The accuracy and precision of the method were evaluated, and relative standard deviations were within 7%. Our method was successfully applied to hair samples obtained from long-term MA abusers and SG users. (+)-MA and (+)-AP were detected from three MA abusers at concentrations of 0.79-20.85 and 0.04-3.30 ng/mg, respectively. On the other hand, (-)-MA, (-)-AP, DMSG, and SG were detected in three SG users at concentrations of 2.48-9.05, 0.72-3.10, 0.12-0.59, and 0-0.04 ng/mg, respectively. Based on our obtained data, discrimination of MA abusers from SG users was considered to be possible by comparing optical isomers of MA and AP, the existence of DMSG and/or SG, and the concentration ratio of AP to MA in hair samples.