NCJ Number
138334
Journal
Journal of Forensic Sciences Volume: 37 Issue: 4 Dated: (July 1992) Pages: 969-983
Date Published
1992
Length
15 pages
Annotation
A new procedure for the simultaneous detection of delta-9-tetrahydrocannabinol (THC) and its major metabolite, 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH) in serum combines rapid, efficient, solid-phase extraction and simple derivatization by methylation.
Abstract
Analysis and quantitation are performed by gas chromatography/mass spectrometry (GC/MS) using deuterated cannabinoids as the internal standards. Recovery experiments for solid-phase extraction are done by adding the internal standards before extraction to serum samples of known cannabinoid amount and by adding the internal standards after the extraction of serum samples of known cannabinoid amount to acetone eluent. Recovery is calculated by the difference in slope of the calibration curve. These procedures were applied to serum specimens collected from a smoking study of 24 volunteers to evaluate the time course of THC and THC-COOH decline in the serum of individuals who had smoked marijuana. Blood specimens were taken before and 40, 100, 160, and 220 minutes after smoking. Concentrations of THC and THC-COOH varied considerably among subjects due to their different smoking techniques. When GC/MS assay techniques were applied to the analysis of 212 serum samples from forensic cases, the presence of THC and THC-COOH could only be confirmed in about 70 percent of serum samples qualified as positive in screening tests with immunoassay. The authors conclude that forensic scientists should connect cannabinoid serum concentrations, time of ingestion, and drug effects, especially in cases involving motor fatalities, homicides, and impaired motorists. 51 references, 2 tables, and 7 figures