Mixed immunosorbent for selective on-line trace enrichment and liquid chromatography of phenylurea herbicides in environmental waters

An immunosorbent containing antiisoproturon and antichlortoluron antibodies immobilised on aldehyde-activated silica was employed for the on-line preconcentration and liquid chromatography-diode array detection of several phenylureas. The efficiency of the coupling of the immunosorbent to the liquid chromatographic system and the characteristics of the immunosorbent were evaluated. The on-line system allowed the selective trace enrichment of chlortoluron, isoproturon, metobromuron, linuron and chlorbromuron at the 0.05-0.5 mu g l(-1) level in ground and river waters and provided detection limits in the range 0.01-0.03 mu g l(-1) by percolating only 10 ml of water sample. The proposed method was validated by analysing freeze-dried tap water samples with a high content in pesticides of different chemical functionalities. The results obtained mere compared with the mean value obtained in an interlaboratory exercise.