A high-throughput method based on microwave-assisted extraction and liquid chromatography–tandem mass spectrometry for simultaneous analysis of amphetamines, ketamine, opiates, and their metabolites in hair

A total sample-preparation and analysis time of 50 min is required for the high-throughput method of hair analysis proposed in this paper. The method is applicable to analysis of drugs commonly used in Asia, and their metabolites—methamphetamine (MA), amphetamine (AMP), methylenedioxymethamphetamine (MDMA), methylenedioxyamphetamine (MDA), ketamine (K), norketamine (NK), dehydronorketamine (DHNK), 6-acetylmorphine (6-AM), morphine (MOR), and codeine (COD). Cut and weighed hair (10 mg) was incubated for 3 min with methanol–trifluoroacetic acid (TFA) during microwave-assisted extraction (MAE) at 700 W. The incubation solution was evaporated, the residue was reconstituted in deionized water–methanol, 99:1 (v/v), and 20 μL was injected on to a core-shell column (50 × 4.6 mm, 2.6 μm particle size) for liquid chromatographic–tandem mass spectrometric (LC–MS–MS) analysis. Gradient elution separation was performed in 8 min at a flow rate of 1 mL min−1. No signal interfering with any of the analytes was found in fourteen blank hair samples from different sources. The limits of detection and quantification were 0.5 pg mg−1 and 2.0 pg mg−1, respectively, for MA, AMP, MDMA, MDA, K, NK, and DHNK, and 2.0 pg mg−1 and 5.0 pg mg−1, respectively, for 6-AM, MOR and COD. The linear range was between the LOQ and 1000 pg mg−1, and the correlation coefficients were all greater than 0.999. Investigation of matrix effects revealed that all the analytes were suppressed by less than 20 % and the standard deviation (SD) was always less than 7 %. Recovery was always greater than 90 % and the SD for each compound was less than 6 %. Precision and accuracy for each analyte were within 15 %. Eight authentic hair specimens from known drug abusers were successfully analyzed. Compared with traditional overnight incubation methods, the rapid 3-min extraction time achieved similar or greater extraction yields. Sample preparation by MAE was a reliable procedure for extraction of the analytes from hair but substantially simpler and faster than other methods.