Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2000
Publication Date: 6/1/2001
Interpretive Summary: Sulfathiazole (STZ) is a sulfonamide antibiotic that is commonly used in the livestock industry to prevent or treat bacterial infections. Although the sulfonamide drugs are useful for keeping animals healthy, drug residues should not be present in animal products that are brought to market. In order to detect improper use of these important drugs in the pork industry, a sensitive test was developed to detect residues of these drugs in pig liver. Rapid tests such as the one described here should help producers, as well as government agencies, to screen pork products for the presence of sulfathiazole residues.
Technical Abstract: A series of enzyme-linked immunosorbent assays (ELISAs) based on anti-sulfathiazole (STZ) monoclonal antibodies (Mabs) were developed that can detect STZ below the tolerance level in tissues. The IC50 values (concentrations of STZ inhibiting 50% of binding in a competitive ELISA) for each Mab ranged from 6 to 21 ng mL-1 of STZ. Immunoassays based upon two monoclonal antibodies, STZ-23 and SDM-44, were evaluated for their assay performance using swine liver samples spiked with STZ. Swine liver tissue was analyzed without a complex sample preparation step, with only a simple dilution of swine liver extract being necessary. A good correlation between immunoassay results and spike levels in swine liver (R2 > 0.98) was obtained, demonstrating that the immunoassays are capable of quantifying STZ in swine liver. The cross- reactivities of other sulfonamide drugs and STZ metabolites in these immunoassays were also examined.