Direct injection of urine on a high-performance liquid chromatographic column-switching system for determination of Δ9-tetrahydrocannabinol-11-oic acid with both ultraviolet and electrochemical detection

Lennart Karlsson

Journal of Chromatography. B, Biomedical Sciences and Applications 417: 309-317


ISSN/ISBN: 1387-2273
DOI: 10.1016/0378-4347(87)80124-x
Accession: 061920563

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A method is presented for determination of 9-tetrahydrocannabinol-11-oic acid in urine by means of a fully automated liquid chromatographic system. Aliquots (200 μl) of hydrolysed urine from prison inmates were directly injected onto a pre-column, followed by chromatography on two columns with different selectivity: Cn and C8 columns. To obtain both greater selectivity and a low detection limit a twin-detector principle was used, consisting of both ultraviolet and electrochemical detection. Urine samples found to be positive with the Emit cannabinoid were analysed, and the results were compared with those obtained from a well established gas chromatographic- mass spectrometric method. The precision of the method was 2.8% at a mean concentration of 85 ng/ml and 13.4% for 6 ng/ml of the acid. The detection limit was below 5 ng/ml.