Selective trace enrichment on immunosorbents for the multiresidue analysis of phenylurea and triazine pesticides

The use of immunosorbents for the selective solid-phase extraction of phenylureas and triazines from environmental water is presented. The choice of the haptens used for the synthesis of antibodies that are able to trap the whole group of triazines and phenylureas is discussed, A better knowledge of the nature of the binding sites has been obtained by studies of capacity for the antigen and also for different compounds in the sample either alone or in a mixture. These experiments have proved the occurrence of competition phenomena between the different compounds and have shown their influence on the calibration curves. Applications to surface waters showed the high selectivity of these sorbents. Most of the studied compounds were easily detected in highly contaminated surface water at the 0.1 mu g l(-1) level with no clean-up. The simultaneous identification of different herbicides within a group in unknown samples is strongly supported by this selective multiresidue preconcentration.