Measurement of delta 9-tetrahydrocannabinol (THC) in whole blood samples from impaired motorists.

The major psychoactive cannabinoid in marihuana, delta 9-tetrahydrocannabinol (THC) was measured in 1792 randomly selected blood specimens from erratic motorists arrested for impairment who submitted to blood alcohol sampling. Of these specimens, 14.4% were positive for THC (greater than or equal to 5.5 ng/mL). In those erratic driver specimens negative for alcohol THC positives rose to 23%. Drivers who used marihuana covered a broad age range. Aliquots of hemolyzed blood (10 microL) were analyzed by a sensitive radioimmunoassay (RIA) not requiring extraction. RIA accuracy and specificity were validated by gas liquid chromatography/mass spectroscopy (GLC/MS) split pair analysis (correlation coefficient = 0.93). This initial experience should facilitate and amplify a program designed to set forth the epidemiology of marihuana use in motorists and possible behavioral correlates.

delta 9-Tetrahydrocannabinol by GLC-MS validated radioimmunoassays of hemolyzed blood or serum.

A direct radioimmunoassay (RIA) of delta 9-tetrahydrocannabinol (delta 9-THC) in unextracted hemolyzed blood or serum is described. The dose-response curve in the range of 5-50 ng/mL (serum or blood) was linear on log-logit transformation and iterative weighted regression. Validation studies included testing for precision, accuracy and antibody specificity as well as confirmation of RIA results (marijuana smoker samples) by gas liquid chromatography-mass spectroscopy (GLC-MS). This routine method will greatly augment cannabinoid investigative programs.