Confirmation of Syva enzyme multiple immunoassay technique (EMIT) d.a.u. and Roche Abuscreen radioimmunoassay (RIA) (125I) urine cannabinoid immunoassays by gas chromatographic/mass spectrometric (GC/MS) and bonded-phase adsorption/thin-layer chromatographic (BPA-TLC) methods.

Thirty human urines screened positive by the Syva enzyme multiple immunoassay technique (EMIT) d.a.u. urine cannabinoid assay were also positive for the major marijuana urinary metabolite 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) when assayed by gas chromatographic/mass spectrometric (GC/MS) and a noninstrumental qualitative bonded-phase adsorption/thin-layer chromatographic (BPA-TLC) technique. The noninstrumental BPA-TLC procedure was the simpler of the two techniques to perform and interpret. Assay of these same samples by the Roche Abuscreen radioimmunoassay (RIA) for cannabinoids (125I) revealed that reliance on the 100-ng/mL equivalent positive calibrator yielded a high incidence of false negative results (10 out of 30). The performance of these same 4 assays on 30 true negatives also was evaluated. All samples were negative for cannabinoids by EMIT and RIA, and for THC-COOH by BPA-TLC. GC/MS assay, however, detected spurious low levels of approximately 5-ng/mL THC-COOH in two instances. Because of this, a reliability level of 10 ng/mL was set for the routine quantitative confirmation of THC-COOH by the GC/MS method.

Ecstacy: a review of MDMA and MDA.

The Drug Enforcement Administration classified the drug methylenedioxymethamphetamine, MDMA, also known as Ecstacy, as a Schedule I controlled substance on July 1, 1985. The controversy surrounding the classification of MDMA is related to the question of its efficacy as an adjunct to psychotherapy and the larger issue of how to regulate the production and use of designer drugs. The authors review the literature on MDMA and its predecessor, MDA, a substance that differs from MDMA by one methyl group.

Improved approach to sequential addition immunoassay.

In the usual sequential addition enzyme immunoassays for drugs, the activity of the drug-labeled enzyme decreases continuously with time as more of it is bound to antibody. Sensitivity also decreases; the activity immediately after mixing is the most sensitive indicator of drug concentration. The reaction of enzyme-drug with antibody can be stopped by saturating the antibody with a larger quantity of unlabeled drug, which reacts with the antibody faster than does the enzyme-labeled drug. When drug is added soon after the reaction starts, the enzyme activity is stabilized and the sensitivity to small quantities of antigen is increased. This approach, with modification, should be applicable to sequential immunoassays in which other kinds of labels are used. The enzyme activity can be measured for a longer time, with the predictable increase in precision, as well as the ability to detect smaller quantities, to use less reagent, and to use end-point rather than kinetic assays.