Simultaneous determination of selegiline, desmethylselegiline, R/S-methamphetamine, and R/S-amphetamine in oral fluid by LC/MS/MS

PurposeIt is crucial for forensic analysis to differentiate clinical use from illegal abuse. Selegiline (SG) is mainly metabolized to desmethylselegiline (DM-SG), R-(-)-methamphetamine (R-MA) and R-(-)amphetamine (R-AM); while abused methamphetamine and amphetamine mainly contain the S-(+)-form. The aim of this study was to simultaneously determine SG, DM-SG, R/S-MA, and R/S-AM in human oral fluid (OF) and to differentiate clinical use from illegal use. We also aim to apply the present method to the OF samples from authentic cases in forensic toxicology.MethodsLiquid-liquid extraction and liquid chromatography-tandem mass spectrometry operating in positive ion multiple-reaction monitoring mode were utilized. The chromatographic system consisted of a Chirobiotic(TM) V2 column (2.1mmx250mm, 5m) and a mobile phase of methanol containing 0.1% (v/v) glacial acetic acid and 0.02% (v/v) ammonium hydroxide.Results and conclusionsThe calibration curves were linear from 1 to 100ng/mL, and r>0.995 for all analytes with imprecisions15% and accuracy between 85 and 115%. Extraction recoveries ranged from 46.3 to 104.7% with coefficient of variation (CV)10.3% and matrix effects (MEs) ranged from 47.4 to 114.8% with CV12.9%. The lower limit of quantification was 0.2ng/mL for SG and DM-SG and 1.0ng/mL for S-MA, R-MA, S-AM and R-AM. The present method is simple, rapid (accomplished in 12min), sensitive, and validated by authentic samples.