EVALUATION OF AN ELISA KIT FOR THE DETECTION OF METRIBUZIN IN STREAM WATER

A recently developed magnetic-based ELISA test kit for the herbicide m etribuzin thylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] was evalu ated for its reproducibility, accuracy, and comparability to results f rom a gas chromatography/mass spectrometry (GC/MS) technique for the d etermination of metribuzin in stream water. Replicated metribuzin dete rmination in stream water showed good daily reproducibility (CV < 10%) except at low concentrations (less than or equal to 0.68 mu g L(-1)). Although the assay correlated well (r = 0.954) with GC/MS results, th e correlation was improved (r = 0.990) when concentrations less than o r equal to 0.68 mu g L(-1) were omitted. Predicted accuracy by the met ribuzin assay was tested in two matrices [stream and deionized (DI) wa ter]. Deionized water matrix exhibited excellent agreement between the theoretical and predicted metribuzin levels, indicating a high degree of accuracy. Predicted metribuzin concentrations were slightly elevat ed compared to theoretical concentrations in stream samples; however, no significant difference (p < 0.05) was found between the two sample matrices. This ELISA was found to tolerate an excessive amount of seve ral chemical substances routinely found in environmental samples as we ll as a wide range of pH levels. Overall, the assay illustrated the ab ility to efficiently and accurately predict concentrations of metribuz in in stream water and demonstrated the utility of the ELISA technique as a screening tool for the determination of metribuzin in stream sam ples.