Determination of amphetamine-type stimulants, ketamine and metabolites in fingernails by gas chromatography-mass spectrometry

A gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the simultaneous qualification and quantification of methamphetamine (MA), amphetamine (AP), 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3,4-methylenedioxy-N-amphetamine (MDA), ketamine (KET) and norketamine (NKT) in fingernails. Fingernail samples (20 mg) were washed with distilled water and methanol, digested with 1.0 M sodium hydroxide at 95 degrees C for 30 min, and then extracted with ethyl acetate. Extract solutions were evaporated to dryness, derivatized using heptafluorobutyric anhydride (HFBA) at 60 degrees C for 30 min, and analyzed by GC-MS. The linear ranges were 0.1-20.0 ng/mg for AP, MDMA and NKT, 0.2-20.0 ng/mg for MA and MDA, and 0.4-20.0 ng/mg for KET, with the coefficients of determination (r(2) >= 0.9989). The intra-and inter-day precisions were within 7.1% and 10.6%, respectively. The intra- and inter-day accuracies were -10.9% to 0.8% and -4.3% to 4.5%, respectively. The limits of detections (LODs) and the limits of quantifications (LOQs) for each analyte were lower than 0.094 ng/mg and 0.314 ng/mg, respectively. The recoveries were in the range of 72.3-94.9%. The average fingernail growth rates of two subjects for three years and six subjects for two months were 3.12 mm/month and 3.16 mm/month, respectively. The method proved to be suitable also for the simultaneous detection and quantification of MA, MDMA, KET and their metabolites in fingernails. (C) 2009 Elsevier Ireland Ltd. All rights reserved.