RAPID MAGNETIC PARTICLE-BASED ELISA ASSAY COMPARED WITH GAS-CHROMATOGRAPHY NITROGEN PHOSPHORUS DETECTION FOR DETERMINING ATRAZINE IN FREEZE-DRIED WATER SAMPLES

The determination of atrazine in freeze-dried water samples containing simazine, 0.6 % glycine as stabilizer and other pesticides has been compared using three different techniques: (i) direct rapid-magnetic particle-based ELISA, (ii) dichloromethane liquid-liquid extraction (LLE) and Florisil column clean-up prior to ELISA determination and (iii) LLE, Florisil column clean-up and gas chromatography with nitrogen phosphorus detection (GC-NPD). The methodology developed in this paper has shown the advantages of the introduction of a clean-up step prior to ELISA determination and its correlation with GC-NPD determinations. Atrazine could be determined at levels between 0.1 to 5 mu g l(-1) in water samples using the different methods described in this paper. The crossreactivity problems found in the ELISA test associated with the presence of simazine are also discussed.