Confirmatory Method for Determination of 11-Nor-Δ9-Tetrahydrocannabinol-9-Carboxylic Acid in Urine Samples Using Gas Chromatography–Mass Spectrometry (GC/MS)

Gas chromatography mass spectrometry (GC/MS) analysis of 11-Nor-Δ⁹-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) and the major metabolite of tetrahydrocannabinol in biological samples is reported The THC metabolite obtained by alkaline hydrolysis from urine samples were extracted using mixture of solvents followed by trimethylsilylation. The derivatized extract was submitted to GC/MS analysis of EI-SIM mode. Different factors were studied as pH, temperature and time to establish the best conditions for the determination. The calibration curves of THC-COOH derivatized (THC-COOH-TMS) in urine samples were linear in the concentration range from 10 to 150 ng/ml. The proposed method is able to determine the major metabolite of cannabis derivatives at very low level (10 ng/ml) with high specificity so is analytical procedure can be used as confirmatory method in drug testing of cannabis use.