Capillary electrophoresis immunoassay for 2,4-dichlorophenoxyacetic acid

A capillary electrophoresis (CE) immunoassay format for 2,4-dichlorophenoxy acetic acid (2,4-D) is demonstrated. A fluorescent labeled 2,4-D analog com petes with the analyte of interest for a finite number of binding sites pro vided by anti-2,4-D monoclonal antibodies. CE then provides a means of sepa rating and measuring both the free and antibody-bound fluorescent tracer us ing laser-induced fluorescence detection. For this assay format, the amount of free tracer is a sensitive indicator for the concentration of analyte p resent in the sample. A sequential injection format allows the rapid analys is of a small number of samples. The dynamic concentration range for 2,4-D in either buffer or river water is 5 ppb to 1000 ppb.