On-line 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 triazines and four organophosphorous compounds was carried out using off-line and on-line solid-phase extraction-RPLC-diode-array detection using styrene-divinylbenzene-membrane extraction disks. Both systems are intercompared and their advantages and disadvantages are discussed. Lower limits of detection can be reached by the on-line method, which enables levels of 0.1 mu g l(-1) of most pesticides to be determined in tap 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)).