Capillary Enzyme Immunoassay with Electrochemical Detection for the Determination of Atrazine in Water

A capillary enzyme immunoassay with electrochemical detection has been developed for the determination of atrazine in water. The assay is based on competitive binding between atrazine and alkaline phosphatase-labeled atrazine for a limited number of antibody binding sites. The antibody is attached covalently to a modified capillary surface. The enzymatic product (p-aminophenol) is detected by amperometric flow injection analysis. The calibration curve for atrazine has a linear range of 0.10-10.0 μg/L and a detection limit of 0.10 μg/L. An assay including six standards can be done in less than 60 min. Intra- and inter-assay precisions at 0.1 and 5.0 μg/L are 9 and 8% and 6 and 10%, respectively. Recoveries of added atrazine from commercial bottled water, tap water, and Ohio River water at 0.50 and 5.0 μg/L range from 100 to 115%. Simple filtration is the only step needed for sample cleanup.