Liquid Chromatography-High Resolution Mass Spectrometry for the Determination of Three Cannabinoids, Two (-)-trans-Δ ⁹-tetrahydrocannabinol Metabolites, and Six Amphetamine-Type Stimulants in Human Hair

Since cannabis and amphetamine-type stimulants (ATS) are drugs of abuse used alone and concurrently worldwide, it is important to analyze them simultaneously. However, there are no reports of analytical method for the simultaneous extraction of these compounds and metabolites in hair samples of suspected drug abusers, due to the different chemical properties of acidic and lipophilic cannabinoids, and basic and hydrophilic ATS. We developed a liquid chromatography-high resolution mass spectrometry (LC-HRMS) method for the quantification of cannabidiol (CBD), cannabinol (CBN), (-)-trans-Δ⁹-tetrahydrocannabinol (THC), THC metabolites such as 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH) and THC-COOH-glucuronide (THC-COOH-glu), and six ATS of amphetamine, methamphetamine, phentermine, methylenedioxyamphetamine, methylenedioxymethamphetamine, and methylenedioxyethylamphetamine in the least amounts of human hair samples. The pulverized hair samples (10 mg) were extracted with 1 mL of 0.5% formic acid in methanol three times, and the supernatants were evaporated in a stream of nitrogen gas. The residue was dissolved and the aliquot was analyzed by LC-HRMS using positive electrospray ionization and the parallel reaction monitoring mode. The lower limits of quantitation were 0.1 pg mg^-1 for THC-COOH and THC-COOH-glu, 4 pg mg^-1 for CBD, CBN, and THC, and 10 pg mg^-1 for the six ATS. Linearity, accuracy, precision, matrix effect, recovery, and post-preparation stability for the 11 analytes were fully validated. The present method was successfully applied to the determination of 11 analytes in hair samples of 10 suspected drug abusers.

Keywords: (−)-trans-Δ(9)-tetrahydrocannabinol and metabolites; Amphetamine-type stimulants; Cannabinoids; Human hair; Liquid chromatography-high resolution mass spectrometry.