Study of the proof for marihuana smoking by gas chromatographic analysis

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For the proof of marihuana smoking, we have tried a new gas chromatographic method for the determination of ^9-tetrahydrocannabinol(THC) in saliva and urine. standard THC was extracted from Cannabis leaves which grown in shimane Prefecture. We developed a gas chromatographic(GC) method with an electron capture defector(ECD) using a reaction pre-column injector for the determination of THC in saliva and urine. One milliliter of the saliva or urine was exrtacted with n-hexane. After washing with each solution of sodium hydroxide and hydrochloric acid, the n-hexane layer was evaporated under nitrogen gas. The residue dissolved in ethyl acetate and THC containing residue was pentafluoropropionic(PFP) derivatives. p,p'-DDT was used as internal standard. The GC/ECD analysis of THC/PFP had a sensitivity of 1 ng/ml of saliva and good linearity was observed on calibration curve in concentration range of 5 to 200 ng/ml. Recoveries of THC added to saliva and urine were 84 % and 64 %, respectively. We have examined experimental smoking for detecting in the saliva and urine of men who smoked a single merihuana cigarette that contained 0.5 g of cannabis leaves equivalent to 10 mg of THC. After smoking model cigarette, the THC levels in saliva were 58.3-250.0 ng/ml at l h, 79.5-156.3 ng/ml at 2 h, and declined at 34.1-74.1 ng/ml 4 h after. On the other hand the urinary THC levels were lower and trace amounts even if the THC can be detectable. In conclusion, the capillary GC/ECD analysis of THC in saliva would be useful for the detection of marihuana abusers.