|Muldoon, Mark - STRATEGIC DIAGNOSTICS INC|
|Deshpande, Sudhir - LJL BIOSYSTEMS|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 16, 1999
Publication Date: N/A
Interpretive Summary: Sulfadimethoxine is a drug that is used in the beef, pork and poultry industry to prevent disease due to bacterial infection. Although the drug is useful for keeping animals healthy, drug residues should not be present in meat products that are brought to market. Therefore, a simple, rapid test was developed that is able to detect residues of this drug in food products. The test is more sensitive than a previously developed test and can be used to quickly screen many samples. Rapid tests such as the one described here should help producers, as well as government agencies, to screen food for the presence of sulfadimethoxine residues.
Technical Abstract: Several rapid extraction methods were evaluated for use with a monoclonal antibody-based ELISA for sulfadimethoxine (SDM) in chicken liver tissue. These included an aqueous extraction with or without ultrafiltration, an acetonitrile/water extraction, a methanol/water extraction, and an acetone extraction method. The organic extraction methods were evaluated with or without solvent evaporation prior to dilution into assay buffer for the ELISA. The aqueous-based extraction methods were compatible with the ELISA. However, of the organic extraction methods, only the acetone liver extract after solvent evaporation was compatible with the ELISA. The ELISA coupled to the aqueous-based and acetone extraction methods and an HPLC method were evaluated for the analysis of chicken liver tissues fortified with SDM at levels from 0.2 ppm to 0.025 ppm. Mean SDM recoveries for the HPLC method, and ELISA method after aqueous extraction, aqueous extraction and ultrafiltration, and acetone extraction, evaporation, and reconstitution, were 68.9%, 95.7%, 60.1%, and 52.5%, respectively. For the analysis of samples obtained from an SDM incurred residue study, HPLC and ELISA analysis of the same extract gave results that were highly correlated (p<0.0001). However, results obtained from the analysis of aqueous extracts by ELISA were much higher than those obtained by the HPLC. This was attributed to the coextraction of cross-reactive SDM- related residues that were not detected by the HPLC method. Use of the ELISA with a rapid aqueous extraction method for residue monitoring purposes should consider the presence of these unregulated residues in data interpretation.