Submitted to: Journal of Association of Official Analytical Chemists International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2003
Publication Date: 8/1/2003
Citation: DONOGHUE, D.J., SCHNEIDER, M.J. COMPARISON BETWEEN A BIOASSAY AND LIQUID CHROMATOGRAPHY-FLUORESCENCE-MASS SPECTROMETRY FOR THE DETERMINATION OF INCURRED ENROFLOXACIN IN WHOLE EGGS. JOURNAL OF ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS INTERNATIONAL. 2003. v. 86. p. 669-674. Interpretive Summary: Enrofloxacin is a fluoroquinolone antibiotic which is currently approved for use in broiler chickens in the U.S. Treatment of animals used for food with fluoroquinolones has generated increasing concern as the presence of these residues in food may lead to increased microbial resistance in humans. Thus, effective methods are required to monitor levels of fluoroquinolone residues in meat and related products such as eggs. We have now developed, evaluated and compared two methods for the analysis of enrofloxacin in eggs, a microbial assay and a liquid chromatography-fluorescence-mass spectrometry(n) assay. Each method was used for analysis of a series of enrofloxacin-incurred eggs and the results were very comparable. The liquid chromatography-fluorescence-mass spectrometry(n) assay has the benefit of confirming the identity of the enrofloxacin present, while the microbial assay may be used as an effective, rapid, initial screening method for large numbers of samples. Both methods are promising tools for use by regulatory agencies such as FSIS.
Technical Abstract: Enrofloxacin is a fluoroquinolone antibiotic approved by the U.S. Food and Drug Administration for use in meat-type poultry but not poultry producing eggs for human consumption. Previous research has demonstrated that if enrofloxacin is therapeutically used for treatment of disease, it will transfer into eggs. Current analytical techniques to monitor for enrofloxacin residues in eggs, although accurate, are expensive and difficult to perform. Our laboratories have developed a bioassay which is rapid, easy to perform, and relatively inexpensive, to detect fluoroquinolone residues in eggs. The bioassay is an agar diffusion microbiological method using Klebsiella pneumoniae, (ATCC 10031) as an indicator organism. Assay plates are prepared with 8 mL of Mueller Hinton agar with Klebsiella pneumoniae at concentration of 1 x 10(6)/mL. The purpose of this study was to compare this bioassay with an LC-Fluorescence-MS(n) method to detect incurred enrofloxacin residues in eggs. Results demonstrate that both methods are capable of detecting incurred fluoroquinolone residues in eggs. During the three-day dosing period of hens (Day 1, 2 and 3) and following drug withdrawal (Days 5, 7 and 9), both of these methods were able to detect incurred enrofloxacin in eggs within a 99% confidence level above the zero tolerance established by the FDA. The LC-Fluorescence-MS(n) method has the benefit of providing confirmation for fluoroquinolones, while the bioassay may be used as an effective, rapid screening method for detection of illegal fluoroquinolone residues in eggs.