A sensitive immunochromatographic assay using colloidal gold-antibody probe for rapid detection of pharmaceutical indomethacin in water samples.

One-step membrane-based competitive immunochromatographic assay using colloidal gold-antibody probe for rapid detection of indomethacin (IDM) in water samples was developed. A positive reaction as a result of the remaining gold-antibody conjugate combining with antigen coated on the membrane was obvious by visual detection. Under optimal conditions, the visual detection limit was found to be 0.1 ngmL(-1), which was about 10-1000 times lower than those in published literatures, demonstrating the high sensitivity of the assay. The stability test indicated the immunochromatographic strips could be used for 8 weeks at room temperature without significant loss of activity. Real water samples were detected by the assay and confirmed by enzyme-linked immunosorbent assay. The assay time for indomethacin detection was less than 10 min, suitable for rapid testing on-site.