Evaluation of atrazine positive and false positive immunoassay detections in ground water

Abstract

False positive responses on an atrazine (6‐chloro‐N‐ethyl‐N'‐(l‐methylethyl)‐1, 3, 5‐triazine‐2, 4‐diamine) immunoassay kit were investigated to explain possible causes for these occurences. Ground water samples were evaluated with the immunoassay kit and positive responses (>0.20 μg L^‐1) were confirmed using gas chromatography/mass spectrometry (GC/MS). Non‐confirming samples (false positives) were analyzed for seven additional compounds on GC. Resulting GC/MS and GC analyses showed that 70% of the false positives could be attributed to two compounds. Prometon (6‐methoxy‐N,N'‐bis(l‐methylethyl)‐1, 3, 5‐triazine‐2, 4‐diamine) was responsible for the majority (64%) of the false positive responses The atrazine metabolite, deethylatrazine (2‐chloro‐4‐amino‐6‐isopropylamino‐1, 3, 5‐triazine), was responsible for the other 6% of the false positives measured. Unattributed false positives (30%) were probably due to an overestimation of pesticide concentrations in the kit's lower detection range.

Key words:

• immunoassay
• false positive
• atrazine
• prometon