Colloidal gold-based immumochromatographic assay for detection of diethylstilbestrol residues

One‐step membrane‐based competitive colloidal gold‐based immunoassays in immunochromatographic formats for the rapid detection of diethylstilbestrol (DES) were developed. Nitro‐cellulose membrane strip was separately coated with goat anti‐rabbit IgG (control line) and DES hapten–ovalubumin conjugate (test line). Anti‐DES polyclonal antibody labeled with colloidal gold particles was first incubated with DES. A positive reaction as a result of the remaining antibody–gold conjugate combining with antigen coated on the membrane was obvious by visual detection, with detection limits for immunochromatographic of 0.5 µg/kg for detecting DES standard solution, and the limit of detection was 5 µg/kg for detecting the DES spiked in swine pork and liver. The assay time for test was less than 5 min, suitable for rapid testing on‐site. Copyright © 2006 John Wiley & Sons, Ltd.