Determination of amphetamines in hair samples using microextraction by packed sorbent and gas chromatography-mass spectrometry.

Abstract

Several protocols for the analysis of amphetamine-type stimulants (ATS) in hair have been developed over the years, with microextraction by packed sorbent (MEPS) being used for drugs like opiates, cocaine and ketamine. However, concerning ATS determination in hair samples, this approach has only been applied so far to amphetamine (AMP) and methamphetamine (MAMP). This study aimed at developing and validating a MEPS-based procedure for the determination in hair of not only AMP and MAMP but also of 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), 1-(1,3-benzodioxol-5-yl)propan-2-yl (ethyl)amine (MDE) and N-methyl-1-(1,3-benzodioxol-5-yl)-2-aminobutane (MBDB) as well. Hair, 50 mg, was incubated with 1 M sodium hydroxide (NaOH) at 45°C overnight, neutralization with 10 M hydrochloric acid (HCl) and centrifugation followed. The design of experiments approach was used for MEPS optimization, with the final optimized conditions including conditioning (250 μL methanol and deionized water), loading (18 × 100 μL) and elution (7 × 100 μL 2% NH₄OH in acetonitrile). The eluted extract was evaporated to dryness and underwent microwave-assisted derivatization with N-methyl-bis(trifluoroacetamide) (MBTFA), and it was afterwards injected onto the gas chromatography-mass spectrometer (GC-MS). The obtained recoveries ranged between 8% and 14% for AMP, 14% and 20% for MAMP, 10% and 15% for MDA, 18% and 28% for MDMA, 25% and 43% for MDE and 34% and 52% for MBDB, and the method was linear from 0.2 to 5.0 ng/mg. Precision and accuracy were in accordance with international method validation guidelines. This novel method involving MEPS coupled to GC-MS offers a swift, eco-friendly and cost-effective alternative to traditional procedures for detecting these AMPs in hair samples.