USE OF STOPPED-FLOW FLUORESCENCE POLARIZATION IMMUNOASSAY IN DRUG DETERMINATIONS

The stopped-flow technique was used jointly with fluorescence polarization immunoassay for the kinetic determination of haptens. Two different types of analytes, namely benzodiazepines and tricyclic antidepressants, were assayed in order to assess the advantages of this novel approach over the conventional equilibrium technique. Kinetic data can be obtained within a few seconds after the reactants have been mixed, which allows ready application of this technique to routine analyses. The within- and between-assay precision data are better and detection limits lower than those afforded by conventional fluorescence polarization 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 with those obtained by using the conventional method.