ASSESSMENT OF AN AUTOMATED IMMUNOASSAY BASED ON KINETIC INTERACTION OF MICROPARTICLES IN SOLUTION FOR DETERMINATION OF OPIATES AND COCAINE METABOLITE IN URINE

A recently introduced automated immunoassay which is based on kinetic interaction of microparticles in solution (Roche ONLINE), was evaluate d for the detection of cocaine metabolite benzoylecgonine (BE) and opi ates in human urine. Cross-reactivity for the opiates morphine (100%), codeine (88%), 6-monoacetylmorphine (88%), and morphine 3-glucuronide (72%) was assessed. Analytical recovery evaluated on blank urines spi ked with 0, 250, 300, 350, and 500 mu g/L of morphine and BE (n = 10), varied from 85.2 to 100.2% for opiates and from 81.4 to 93.1% for the cocaine metabolite. The within-day precision ranged from 1.4 to 4.7% for morphine and from 4.2 to 4.8% for BE. The repeatability of the sta ndards over 1 month was 1.0-3.3% for opiates and 1.7-5.1% for BE, and thus allowing measurements to continue over 30 days without re-calibra tion. This method compared favourably with the SYVA EMIT d.a.u(TM) sys tem and gas chromatography/mass spectroscopy (GC/MS) methods.