COMPARISON OF AN ENZYME-IMMUNOASSAY AND GAS-CHROMATOGRAPHY MASS-SPECTROMETRY FOR THE DETECTION OF ATRAZINE IN SURFACE WATERS

To determine the reliability of an enzyme immunoassay (EIA) for atrazi ne, we collected water samples and analyzed them for herbicide content by both EIA and standard gas chromatography/mass spectrometry (GC/MS) techniques. The commercially available EIA uses antibodies linked to magnetic particles to determine sample atrazine concentrations and req uires less than 2 h to analyze a run of 50 samples. The EIA was intern ally consistent with variation of less than 3% between 156 duplicate s tandards that were run to develop standard curves. For the 217 samples examined, atrazine concentrations measured by the two analytical tech niques were highly correlated (r = 0.96). Compared to concentrations m easured by GC/MS, the EIA produced no false negatives and few false po sitives (5.53%). The EIA tended to overestimate atrazine concentration s slightly, probably the result of cross-reaction in the EIA by atrazi ne metabolites and structurally related triazine herbicides. Even so, the EIA proved to be a reliable, relatively simple, and cost-effective screening technique for atrazine contamination.