Qualitative high performance thin layer chromatography (HPTLC) analysis of cannabinoids in urine samples of Cannabis abusers.

BACKGROUND & OBJECTIVES Cannabis is one of the most commonly abused drugs worldwide. There is a distinct clinical correlation between cannabis abuse and mental disorders. However, it is essential to establish cannabis intake in the abusers in order to establish causality between cannabis and psychiatric illness. The limitations of current detection methods using commercial cassettes prompted us to standardize the method of extraction and detection of cannabinoids in the urine samples of cannabis abusers attending a de-addiction centre in south India. METHODS In this study, diagnostic tests on 102 male patients suspected with cannabis abuse were done. Liquid-liquid extraction of cannabinoids from urine was done and screened by Duquenois-Levine, fast blue B salt and p-dimethylaminobenzaldehyde (p-DMAB) tests. All the results were confirmed by high performance thin layer chromatography (HPTLC). Samples were considered positive for cannabis based on the positive indication in colour test and by detection of 11-nor-delta(9) tetrahydrocannabinol-9-carboxylic acid (THC-COOH) on HPTLC. RESULTS Based on the colour tests and HPTLC, cannabis abuse was detected in 64 of 102 patients tested. HPTLC method was found to be sensitive for detection and possible quantitation of THC-COOH. INTERPRETATION & CONCLUSION We report the standardization and utility of cannabinoid extraction, screening and detection by HPTLC in the urine samples of cannabis abusers. The HPTLC method was found to be high throughput, sensitive, reproducible and cost-effective compared to commercial kits.