Quantitative analysis of 2,4-dichlorophenoxyacetic acid in water samples by two immunosensing methods

Two sensitive methods based on a monoclonal anti-2,4-dichlorophenoxyacetic acid (2,4-D) antibody, a now injection immunoanalysis (FIlA), and a fiber optic immunosensor are described and evaluated for the quantitative determination of 2,4-D in water samples. Detection limits for 2,4-D of similar to 0.03 mu g/L with FIIA and 0.2 mu g/L with the fiber optic immunosensor can be achieved, i.e. well below the maximum concentration permitted, in the case of FIIA, by the EC Drinking Water Directives of 0.1 mu g/L. The midpoints of the 2,4-D test are found at concentrations of 0.3 mu g/L with FIIA and 10 mu g/L with the fiber optic immunosensor. Measurable concentrations range from 0.03 to 3 mu g/L with FIIA and from 0.2 to 100 mu g/L with the fiber optic immunosensor. The FILA did not require concentration or cleanup steps for ground and surface water samples. In addition, validation experiments with GC/MS showed a good correlation of the data for the FIIA system. However, both tests can be applied as alarm systems for monitoring potential 2,4-D contamination in environmental water samples.