title: 125I radioimmunoassay of delta-9-tetrahydrocannabinol in blood and plasma with a solid-phase second-antibody separation method.
abstract: In this sensitive and specific radioimmunoassay for delta-9-tetrahydrocannabinol, an iodinated tracer with high specific activity and a solid-phase separation are used. Within-run coefficients of variation for 5.0 and 30.0 microgram/L concentrations were 7.8 and 4.2% for plasma and 14 and 10.6% for hemolyzed blood specimens, respectively. Day-to-day coefficients of variations ranged from 7.3 to 13.6% (for 7.6 to 33.0 microgram/L concentrations) for plasma and 13.4 to 18.1% (3.0 to 52.1 microgram/L) for hemolyzed blood specimens. Data for time after start of smoking of a standard THC-containing cigarette vs the concentration of delta-9-tetrahydrocannabinol in the plasma were similar to those obtained by others. Positive plasma specimens from the smoking study were analyzed by gas chromatography-mass spectrometry and by our radioimmunoassay. Nonparametric statistical comparison and linear regression (r2 = 0.972) showed that results by the two methods of analysis correlate well. The sensitivity of the assay was at least 0.3 microgram/L for plasma, 1.1 microgram/L for hemolyzed blood.
mesh_terms: D000328:Adult; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000097:blood* / Q000276:immunology; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D010949:Plasma / Q000032:analysis; D011863:Radioimmunoassay / Q000379:methods*
chemical_list: D013759:Dronabinol