PREPARATION AND EVALUATION OF IMMUNOSORBENTS FOR SELECTIVE TRACE ENRICHMENT OF PHENYLUREA AND TRIAZINE HERBICIDES IN ENVIRONMENTAL WATERS

The development of new immunosorbents for the selective solid-phase ex traction of phenylurea and triazine herbicides from environmental wate rs is presented. The production and purification of polyclonal antibod ies against isoproturon and atrazine are described. The immunoconjugat es were characterized by electrospray mass spectrometry before immuniz ation of rabbits. Silica-based sorbents were shown to be more effectiv e than rigid hydrophilic polymers for the covalent coupling of antibod ies because no nonspecific interactions occurred between analytes and the silica matrix. Off-line enrichment using cartridges shows that the immunosorbent can trap several analytes in the same group (9 in a mix ture containing 13 phenylurea herbicides, and 6 in a mixture containin g 9 triazine herbicides). A stepwise elution with increasing amounts o f methanol showed that the analytes had different affinities for the i mmunosorbents. The elution conditions were found to be similar for the two immunosorbents, and 70% methanol was necessary for the efficient desorption of all the analytes. High selectivity was illustrated by an alyzing Seine river samples spiked with mixtures of phenylurea or tria zine herbicides. No interfering compounds were detected in the chromat ograms, and the base lines were as clean as those corresponding to dri nking water samples. Isoproturon was easily detected in surface waters at the 0.1 mu g/L level with no cleanup. These results demonstrate th e potential of such immunosorbents for the selective preconcentration of herbicides for multiresidue analysis. The identification of herbici des in unknown samples is strongly supported by the selective preconce ntration.