Validated Direct Blood Δ9-THC Radioimmune Quantitation

Abstract

Δ⁹-THC, the active cannabinoid and its major metabolite, 11-nor-9-carboxy-Δ⁹-THC (C-THC), are measurable directly in urine, saliva, and blood. The Δ⁹-THC antiserum is capable of discriminating closely related cannabinoids. The relevant radioimmune results correlate well (corr. coef. 0.87) with GC-mass spectroscopic measurements of split samples performed elsewhere. It is, therefore, concluded that an extremely specific Δ⁹-THC radioimmune assay has been developed. Salivary cannabinoid levels are not expected to discriminate between affected and nonaffected individuals. Since blood Δ⁹-THC concentrations correlate with overt intoxication, this direct RIA has significant forensic implications.