Simultaneous determination of eight underivatized amphetamines in hair by high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS).

The aim of this study was to develop, optimize, and validate an analytical procedure to determine a group of eight amphetamines, amphetamine (AMP), ephedrine (EP), methcathinone (MTC), paramethoxyamphetamine (PMA), methamphetamine (MA), methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), and methylenedioxyethylamphetamine (MDEA), in hair. The target substances were extracted with 1-chlorobutane after alkaline (1M NaOH) digestion and analyzed underivatized with high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS). APCI-MS parameters such as fragmentor and capillary voltage, corona current, drying gas temperature and flow rate, vaporizer temperature, and nebulizer gas pressure were optimized with the application of flow injection analysis. Quantitation was performed using selected ion monitoring of protonated molecular ions of the studied drugs, and their deuterated analogues were used as internal standards. The limits of detection were 0.05 ng/mg for MA, MDA, MDMA, and MDEA; 0.10 ng/mg for EP and AMP; and 0.20 ng/mg for MTC and PMA. A linear response was observed for all drugs from 0 to 20 ng/mg. The method was applied to the determination of amphetamines in 93 authentic hair samples obtained from detoxification and methadone treatment patients, revealing the following concentrations: 0.17-17.28 ng/mg (EP), 0.52-2.08 ng/mg (MTC), 0.15-62.52 ng/mg (AMP), 0.10-16.52 ng/mg (MA), 0.10-0.88 ng/mg (MDMA), and 0.10-0.16 ng/mg (MDEA). MDA and PMA were never detected.