EVALUATION OF ATRAZINE POSITIVE AND FALSE-POSITIVE IMMUNOASSAY DETECTIONS IN-GROUND WATER

False positive responses on an atrazine hyl-N'-(1-methylethyl)-1,3,5-t riazine-2,4-diamine) immunoassay kit were investigated to explain poss ible causes for these occurrences. Ground water samples were evaluated with the immunoassay kit and positive responses (>0.20 mu g L-1) were confirmed using gas chromatography/mass spectrometry (GC/MS). Non-con firming samples (false positives) were analyzed for seven additional c ompounds on GC. Resulting GC/MS and GC analyses showed that 70% of the false positives could be attributed to two compounds. Prometon ,N'-bi s(1-methylethyl)-1,3,5-triazine-2,4-diamine) was responsible for the m ajority (64%) of the false positive responses. The atrazine metabolite , deethylatrazine 2-chloro-4-amino-6-isopropylamino-1,3,5-triazine), w as responsible for the other 6% of the false positives measured. Unatt ributed false positives (30%) were probably due to an overestimation o f pesticide concentrations in the kit's lower detection range.