ONLINE PRECONCENTRATION AND LIQUID-CHROMATOGRAPHIC ANALYSIS OF PHENYLUREA PESTICIDES IN ENVIRONMENTAL WATER USING A SILICA-BASED IMMUNOSORBENT

The feasibility of using a silica-based immunosorbent for the selectiv e on-line preconcentration of several phenylurea pesticides in drinkin g and surface waters was demonstrated. The immunosorbent was packed in a precolumn which was used in the same way as a conventional C-18 or PLRP-S precolumn: percolation of aqueous samples through the precolumn , then direct coupling to a C-18 analytical column and desorption usin g an acetonitrile gradient from 20 to 80% acetonitrile. Although the r etention of the different phenylureas was based on antigen-antibody in teractions in the precolumn and on hydrophobic interactions in the ana lytical column, the efficiency of the on-line system was excellent as shown by the on-line preconcentration and analysis of 12 phenylureas o f different polarities. The characteristics of the immunosorbent (cros s-reactivity, breakthrough of analytes, capacity, selectivity and reus ability) were discussed. An application to the analysis of surface wat ers showed the high selectivity of this sorbent. Detection limits from a 50-ml sample were ranging between 0.05 and 0.5 mu g/l for 10 phenyl ureas in a mixture of 13. An application to the rapid monitoring of is oproturon in the river Seine was also reported.