A UNIQUE SOLID-PHASE EXTRACTION COLUMN FOR ISOLATION OF 11-NOR-DELTA-9-TETRAHYDROCANNABINOL-9-CARBOXYLIC ACID IN HUMAN URINE

A sensitive, specific, qualitative, and quantitative extraction procedure followed by an hplc assay of 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) from human urine is developed. Using a new, "mixed mode", bonded silica gel solid phase extraction (SPE) column, the analyte was selectively isolated from the urine component. Following extraction, the presence of THC-COOH was confirmed and quantitated by a UV detector on a Varian 15cm C18 column using 35:65 v/v 50 mM phosphoric acid: acetonitrile at a flow rate of 1.5 mL/min. The limit of detection was 10 ng/mL at a signal to noise ratio of 2.5. The method showed linearity in the 10-300 ng/mL range (r = 0.999) with good precision (RSD 1.4%) and accuracy (87% absolute recovery).