title: Combination of liquid chromatography with ultraviolet detection and gas chromatography with electron-capture detection for the determination of delta 9-tetrahydrocannabinol-11-oic acid in urine.
abstract: A method is described for the determination of delta 9-tetrahydrocannabinol-11-oic acid (delta 9-THC-11-oic acid) in urine by using a combination of liquid chromatography and glass capillary gas chromatography with electron-capture detection. Prior to extraction, the glucuronide conjugate of delta 9-THC-11-oic acid was enzymatically converted to the free acid and delta 8-THC-11-oic acid added as an internal standard. An aliquot of the extract was separated by liquid chromatography and one eluate fraction containing delta 8-THC-11-oic and delta 9-THC-11-oic acids was collected. Before gas chromatographic analysis the acids were converted to their pentafluoropropyl-pentafluoropropionyl derivatives. Authentic urine samples, positive with the EMIT cannabinoid assay, were analysed and the results compared with those obtained from an earlier described gas chromatographic-mass spectrometric method. The detection limit for the overall method was approximately 20 ng/ml. The precision was 8% for a sample concentration of 90 ng/ml of delta 9-THC-11-oic acid in urine.
mesh_terms: D002849:Chromatography, Gas / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: C026502:delta(9)-tetrahydrocannabinol-11-oic acid glucuronide; D013759:Dronabinol