DETERMINATION OF DELTA(9)-TETRAHYDROCANNABINOL FROM HUMAN SALIVA BY TANDEM IMMUNOAFFINITY CHROMATOGRAPHY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Smoking or ingestion of cannabis causes cognitive, perceptual and beha vioural changes, which are responsible for impaired performance in dri ving motor vehicles. In this paper a novel liquid chromatographic assa y for the selective quantification of hg-tetrahydrocannabinol, the maj or indicator of a present cannabis intoxication in saliva, is describe d. The method involves a column-switching procedure and requires an ex tremely simple pre-treatment of the sample. Deproteinized saliva was d irectly injected into the chromatographic system. The clean-up and enr ichment procedure was performed in an immunoaffinity column, followed by the transfer of the antigens to an octylsilica analytical column. T he immunoaffinity sorbent was obtained by covalent immobilization of s pecific antibodies on epoxy-activated silica. The mobile phase consist ed of methanol-aqueous 0.15 mol/l NaCl solution (elution programmed) a nd the analyte was detected by measuring the UV absorption at 220 nm. Using an injection volume of 4.5 mi (dilution 3:2, v/v) the limit of q uantification was 20 ng/ml, at a signal-to-noise ratio of 5, Recoverie s were estimated to be in the range of 70%. Both intra- and inter-day coefficients of variation were below 5%