Determination of cannabinoids in hair by LC-MS/MS for the monitoring of chronic Cannabis consumption

Cannabis is by far the most widely used illicit drug. United Nations Office on Drugs and Crime estimates that in 2009 between 125 and 203 million people worldwide had used Cannabis at least once in the past year. Consumption of this substance of abuse impairs attention, judgement, coordination, balance and other cognitive functions, thus increasing the risk of accidents in work settings and while driving. Therefore it is important to strictly monitor Cannabis abuse. The analysis of abuse substances in hair samples provides useful information on severity and pattern of drug exposure: the chemicals become firmly enclosed in the hair structure and detected over long periods of time, thus allowing the distinction between chronic use and single exposure. The aim of this work is the development of an original LC-MS/MS method for the determination of Δ9-tetrahydrocannabinol, the main psychoactive compound found in Cannabis plants, and its metabolite, 11-nor-Δ9-tetrahydrocannabinol- 9-carboxylic acid, in human hair. Separation of the analytes was achieved on a C18 column, using a mixture of acidified water and acetonitrile as the mobile phase. The detection was performed by a triple quadrupole mass spectrometer, operating in ESI+. It is important to carry out an accurate pretreatment procedure of the biological sample to extract the two cannabinoids from the keratinous matrix. Method validation is in progress.