Monitoring of chronic Cannabis abuse an LC-MSMS method for hair analysis.
An advanced analytical method based on liquid chromatography-tandem mass spectrometry (LC-MSMS), has been developed for the identification and determination in hair of Δ(9)-tetrahydrocannabinol together with its major metabolite 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol. Since the latter is formed endogenously, it allows the assessment of chronic use excluding passive exposure to Cannabis. The sample pre-treatment procedure is based on a feasible incubative extraction followed by a liquid-liquid extraction step. Chromatographic separation was performed using a reversed-phase column and gradient elution with a formic acidacetonitrilewater mobile phase. The limits of quantitation and of detection were 3pgmg and 1pgmg, respectively, for both analytes. The method was successfully applied to the analysis of hair samples from Cannabis abusers the analyte concentrations found ranged from 55 to 100pgmg for Δ(9)-tetrahydrocannabinol and from 5 to 10pgmg for 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol. Accuracy studies also gave satisfactory results (recovery>87%), thus confirming the suitability of the assay for chronic consumption monitoring.