A sensitive enzyme‐linked immunosorbent assay amplified by biotin–streptavidin system for detecting non‐steroidal anti‐inflammatory drug ketoprofen

A sensitive biotin–streptavidin‐amplified enzyme‐linked immunosorbent assay (BA‐ELISA) method was developed for detecting non‐steroidal anti‐inflammatory drug ketoprofen. Compared with traditional ELISA method, the sensitivity of proposed immunoassay was enhanced by the biotin–streptavidin system. Under the optimal condition, the median inhibitory concentration (IC₅₀) was 0.25 ng mL^?1, with minor cross‐reactivity to a number of structural analogs. This developed assay was successfully applied to detect the ketoprofen residues in different fish samples, and good recoveries (72.6–105.5%) were obtained. The results indicated that this immunoassay method could specifically detect trace ketoprofen residues and could be widely used for routine monitoring of food samples.