Enzyme immunochemical detection of the use of hashish and confirmation by thin-layer chromatography

The EMIT cannabinoid assay was used for screening blood and urine after smoking tetrahydrocannabinol (THC; 10 mg) or ingestion of THC (30 mg). Cannabinoid levels in urine remain detectable up to 1 week. Confirmation was done by adsorption of the THC carboxylic acid onto a C18 extraction column and elution with acetone and TLC. The method is simple and sensitive and is applicable with common laboratory equipment. The detection limit is 10 ng/ml, using 10 ml urine.