ESTIMATION OF OPIATES IN URINE BY STOPPED-FLOW FLUOROIMMUNOASSAY

The stopped-flow mixing technique was applied for the first time to the kinetic determination of opiates. For this purpose, a method involving measurement of temporal changes in the fluorescence polarization in the course of competitive immunochemical reactions of the analyte and tracer (fluorescein-labelled morphine) with the antibody was developed. As kinetic data can be obtained in only a few seconds, this new approach is faster than the conventional fluorescence polarization immunoassay, where measurements are carried out at the equilibrium, and lends itself readily to application in routine analyses. The detection limit for morphine in urine was 6.0 ng ml-1, i.e. roughly 4 times lower than that afforded by the conventional method. The mean analytical recovery of morphine from urine was 98.5%.