ONLINE AND OFF-LINE SOLID-PHASE EXTRACTION WITH STYRENE-DIVINYLBENZENE-MEMBRANE EXTRACTION DISKS FOR DETERMINING PESTICIDES IN WATER BY REVERSED-PHASE LIQUID-CHROMATOGRAPHY DIODE-ARRAY DETECTION

The determination of a group of pesticides, two phenylureas, six triaz ines and four organophosphorous compounds was carried out using off-li ne and on-line solid-phase extraction-RPLC-diode-array detection using styrene-divinylbenzene-membrane extraction disks. Both systems are in tercompared and their advantages and disadvantages are discussed. Lowe r limits of detection can be reached by the on-line method, which enab les levels of 0.1 mu g l(-1) of most pesticides to be determined in ta p water, as is required by European Community (EC) rules, whereas the off-line mode gives higher limits of detection, but it is possible to determine the pesticides at levels recomended by EC rules for surface water (1-3 mu g l(-1)).