Hypochlorite adulteration of urine causing decreased concentration of delta 9-THC-COOH by GC/MS

Marijuana is confirmed and quantitated in urine as 11-nor-delta 9-THC-9-COOH by GC/MS in the selected ion monitoring mode after extraction from urine. The addition of varying amounts of household bleach causes significant decreases in the quantitated amounts of tetrahydrocannabinol (THC). Urine samples containing various known amounts of THC (25-219 ng/mL) were spiked with increasing amounts of household bleach (0-64 microL/mL of urine). The samples were extracted using a solid-phase extraction procedure, derivatized, and analyzed by GC/MS. The area counts for the deuterated internal standard versus the native drug, as well as the quantitation for the various spiked samples, were compared with those of the non-adulterated samples. The results demonstrated that there was an inverse relationship between the amount of bleach used and the amount of THC recovered. The area counts for both the deuterated and native THC decreased as the amount of bleach increased. There appeared to be a consistent decrease in the ratio of native to deuterated THC, suggesting that the bleach affected the native drug more than the deuterated compound. The same decrease in THC concentrations were noted when the samples were assayed by an RIA methodology (Roche Abuscreen) as well as by an FPIA assay (Abbott TDx).