ENZYME-IMMUNOASSAY, KINETIC MICROPARTICLE IMMUNOASSAY, RADIOIMMUNOASSAY, AND FLUORESCENCE POLARIZATION IMMUNOASSAY COMPARED FOR DRUGS-OF-ABUSE SCREENING

The newest formulation of the Syva EMIT assay for drugs of abuse, EMIT II, and a new immunoassay, OnLine (Roche), utilizing the kinetic inte raction of microparticles in solution (KIMS) methodology, RIA tests, a nd TDx fluorescence polarization immunoassay (FPIA) procedures were co mpared for marijuana, cocaine, opiates, and barbiturates. Both EMIT II and OnLine immunoassays were performed with a Hitachi 717 analyzer. C alibration curves, the degree of separation between negative and cutof f calibrators, precision, likelihood of carryover from positive to neg ative samples, and overall ease and speed of analysis were evaluated. RIA and OnLine detected 99% of gas chromatography/mass spectrometry (G C/MS)-confirmed marijuana samples; TDx, 95%; and EMIT II, 88%. All fou r immunoassays detected approximately 99% of confirmed cocaine-positiv e urines. RIA, OnLine, and TDx all detected 100% of opiate-confirmed s amples; EMIT II, 97%. Barbiturate assays exhibited the greatest dispar ity, with OnLine and TDx detecting 100% of confirmed positives; EMIT I I, 88%; and RIA, 78%. For a variety of reasons, we prefer the fully au tomated EMIT II and OnLine assays for high-volume urine testing, in co mparison with our laboratory's semiautomated RIA tests and the limited -throughput TDx system. The four immunoassays investigated delivered c omparable performance in terms of detection rates for GC/MS-confirmed positives for some drugs but not for others.