Kinetic determination of atrazine in foods based on stopped-flow fluorescence polarization immunoassay

A very simple and fast method for the direct determination of atrazine in food samples based on the use of stopped-flow fluorescence polarization immunoassay is described. Unlike other immunoassay methods where the analytical signal is obtained when the immunochemical reaction has reached or is close to the equilibrium, this method uses the initial rate of this reaction as the analytical parameter, which is measured in only 4-5 s. This approach minimizes the static signal from the sample matrix, allows the direct analysis of the samples and can be easily adapted to the routine automatic determination of atrazine. The dynamic range of the calibration graph was 0.7-100 ng ml(-1) and the detection limit was 0.2 ng ml(-1). The precision and selectivity of the method were also studied. The analytical recoveries obtained by applying the method to white and red wine, orange juice and tea samples ranged from 80 to 104%. (C) 1998 Elsevier Science B.V. All rights reserved.