USE OF STOPPED-FLOW FLUORESCENCE POLARIZATION IMMUNOASSAY IN DRUG DETERMINATIONS

The stopped-flow technique was used jointly with fluorescence polariza tion immunoassay for the kinetic determination of haptens. Two differe nt types of analytes, namely benzodiazepines and tricyclic antidepress ants, were assayed in order to assess the advantages of this novel app roach over the conventional equilibrium technique. Kinetic data can be obtained within a few seconds after the reactants have been mixed, wh ich allows ready application of this technique to routine analyses. Th e within- and between-assay precision data are better and detection li mits lower than those afforded by conventional fluorescence polarizati on immunoassay. The analytical recoveries ranged between 98.6 and 101. 5% for nordiazepam in urine and between 97.1 and 102.0% for imipramine in serum. The results for serum and urine samples correlated well wit h those obtained by using the conventional method.