Competitive Direct Enzyme-Linked Immunosorbent Screening Assay for the Detection of Sulfamethazine Contamination of Animal Feeds

Abstract

A sensitive screening method has been developed for detecting sulfamethazine (SMZ) contamination of feeds by using either polyclonal or monoclonal antibodies and a direct competitive enzyme-linked immunosorbent screening assay (ELISA). Feed samples of 25.0 g are extracted with 0.5N HCI and centrifuged. The extract is adjusted to pH 7.0 with 3.0N NaOH and recentrifuged. This pH-adjusted extract is used in the EUSA. Levels as low as 0.004 μg SMZ/g feed were detected In supplemented extracts by polyclonal antibodies; levels of 0.4 μg SMZ/g feed were detected by a monoclonal antibody.