Quantitative determination of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid in urine by HPLC

An analytical method for the confirmation and quantitative analysis of the major metabolite of delta 9-tetrahydrocannabinol in urine is presented. Urine samples undergo basic hydrolysis followed by purification using acidic extraction with organic solvents. The HPLC separation is a reverse-phase system on a C18 column with a mobile phase of 45% acetonitrile and phosphate buffer, pH 6.0, followed by ultraviolet detection at 205 nm. The method is used routinely for the confirmation of probation urine samples found to be positive for cannabinoids by radioimmunoassay.