Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 25, 1996
Publication Date: N/A
Ceftiofur is an FDA approved broad-spectrum, beta-lactamase-resistant veterinary cephalosporin for the treatment of respiratory diseases in cattle, horses, and swine. Numerous methods to detect ceftiofur including HPLC and microbiological assays have been described. Using these detection methods, levels in the neighborhood of 0.5 ppm of ceftiofur equivalents are commonly reported. These methods are complex, time consuming and often require expensive equipment. In addition, many of these methods do not detect the major metabolites of ceftiofur. Both desfuroylceftiofur and furoic acid metabolites have been reported in animal tissues. We have developed a sensitive monoclonal antibody-based immunoassay for detecting ceftiofur and its desfuroyl metabolite. Analysis of ceftiofur residues in milk using both fortified samples and incurred residue samples suggest that this competitive enzyme-linked immunosorbent assay (cELISA) is capable of detection of as little as 1 ppb of ceftiofur equivalents in raw milk with no sample preparation, except for dilution. Recovery studies using fortified milk samples obtained from individual cows, as well as milk samples from the bulk tank, have been analyzed. Results from a study where ceftiofur levels were measured in several cows administered the drug over a 10 day period agreed well with published results in which radiolabeled ceftiofur was monitored. Application of the cELISA for measurement of ceftiofur equivalents in bovine tissue and serum also will be presented. Preliminary data suggests that, as in the case of raw milk, residues can be readily measured in beef kidney following a simple buffer extraction and dilution step.