Δ9-Tetrahydrocannabinol by GLC-MS Validated Radioimmunoassays of Hemolyzed Blood or Serum

A direct radioimmunoassay (RIA) of Δ9-tetrahydrocannabinol (Δ9-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.