A flow immunoassay method for the measurement of 2,4-dichlorophenoxyac
etic acid (2,4-D) was developed. The competitive fluorescence immunoas
say relies on the use of antibody- or antigen-coated poly(methyl metha
crylate) particles (98 mu m diameter) as a renewable solid phase. The
assay exhibits a dynamic range of 0.1-100 mu g l(-1) using a monoclona
l antibody or alternatively 10 mu g l(-1) to 10 mg l(-1) using commerc
ially available antiserum. The assay is demonstrated in buffered salin
e solution as well as in aquatic environmental media, The relative err
ors for the environmental matrices were similar to those for the buffe
r control, The precision of concentration values calculated at 1 mg l(
-1) (for the assay using antiserum) mere +/-0.28, +/-0.27 and +/-0.43
mg l(-1) for the buffer, well mater and river water matrices, respecti
vely. The method shows cross-reactivity with compounds of closely rela
ted structure but little cross-reactivity with compounds dissimilar in
structure to 2,4-D. The proposed automated competitive immunoassay me
thod is rapid (between 7 and 15 min per assay), simple and potentially
portable.