Antibody specific to chloramphenicol (CAP) was produced from rabbit that had been immunized with CAP-keyhole limpet hemocyanin (KLH). Using the antibodies, we established a sensitive direct competitive enzyme-linked immunosorbent assay (dcELISA) and a gold nanoparticle immunochromatographic strip (immunostrip) for detection CAP in food samples. In the dcELISA, CAP at levels of 0.15 ng/ml causes 50% inhibition (IC50) of the binding of CAP-horseradish peroxidase to the antibodies. The overall analytical recoveries of CAP (0.25-100 ng/g) added to the honey or milk samples in the dcELISA were 81.9 and 73.7%, respectively. Onsite determination of CAP was accomplished by immunostrips with a detection limit of 0.5 ng/ml and completed within 10 min. Carefully studying 10 honey and 6 milk samples using the dcELISA and immunostrip indicated that all examined samples were negative for CAP. The presented dcELISA and immunostrip methods are sensitive enough for the rapid determination of CAP in the samples.
