Quantitation of Total 11-Nor-9-Carboxy-Delta 9-Tetrahydrocannabinol in Urine and Blood Using Gas Chr

Marijuana, which is made from crushing the leaves, flowers, and sometimes the stems of the plant Cannabis sativa, contains more than 30 cannabinoids. The major psychoactive cannabinoid is delta-9-tetrahydrocannabinol (THC). The major metabolite of THC, 11-nor-delta 9-carboxy-tetrahydrocannabionol (THC-COOH), is excreted in the urine primarily as a glucuronide conjugate and is commonly analyzed in biological specimens for detecting marijuana usage. The procedure described here involves the addition of deuterated internal standard THC-COOH-d9 into the sample followed by hydrolysis of conjugated THC-COOH by alkali. THC-COOH is extracted from urine or blood using liquid–liquid extraction followed by preparation of its trimethylsilyl derivatives. The analysis of derivatized THC-COOH is performed using gas-chromatography/mass spectrometry (GC/MS). Quantification of the drug in a sample is achieved by comparing the responses of the unknown sample to the responses of the calibrators using selected ion monitoring.