Submitted to: Journal of the Association of Official Analytical Chemists
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/11/2007
Publication Date: 12/1/2007
Citation: Schneider, M.J., Reyes-Herrera, I., Donoghue, D. 2007. Evaluation of Serum as a Potential Matrix for Multiresidue Determiantion of Fluoroquinolone Antibiotics in Chicken using Liquid Chromatography-Fluorescence-Mass Spectrometry. Journal of the Association of Official Analytical Chemists. 90(6):1716-1723. Interpretive Summary: Fluoroquinolone antibiotics (FQs) have been used in both medical and veterinary applications. Recently, the U.S. FDA withdrew approval for use of these drugs in chicken, due to concerns over increased microbial resistance. The E.U. allows use of several FQs in chicken, but has set maximum residue limits (MRLs). Whether banned or allowed with a MRL, it is important to have efficient methods available for monitoring chicken for FQ residues. We have now developed a multiresidue method for determination of FQs in both chicken serum and muscle. This method uses extraction followed by liquid chromatography to isolate and separate the FQs. Detection is achieved using two powerful techniques: fluorescence, for measurement of the amount of each FQ present, and mass spectrometry(n) for confirming the identity of each FQ. With this method, we were able to quantitate and confirm the presence of 8 FQs in fortified chicken muscle and serum samples. We also were able to successfully analyze FQ levels in incurred muscle and serum samples. Serum was found to be a much easier matrix to extract, and the ability to use this method with serum, together with the method's efficiency in allowing simultaneous quantitation and confirmation, provides a promising tool for use by regulatory agencies.
Technical Abstract: An efficient multiresidue method was developed for the determination of fluoroquinolones (FQs) in chicken serum, as well as muscle. In this method, FQs are extracted from matrix with ammoniacal acetonitrile, the extracts are defatted and then evaporated. After addition of basic phosphate buffer and filtration, the samples are analyzed by liquid chromatography-fluorescence-mass spectrometryn. This approach allows for simultaneous quantitation (fluorescence) and confirmation (MSn) of the FQs. Using this method, 8 FQs were determined in fortified chicken serum and muscle at levels of 10, 20, 50, and 100 ng/g. Recoveries ranged from 68-90% for muscle and 71-99% for serum, with excellent relative standard deviations (<10%). Limits of quantitation for the FQs ranged from 0.05-5 ng/g for serum and from 0.1-5 ng/g for muscle. Confirmation was achieved by comparison of MS2 or MS3 product ion ratios with those of standard FQ samples. Muscle and serum samples from enrofloxacin-dosed chickens were also analyzed with this method. The results show that enrofloxacin can be determined in both serum and muscle of chickens dosed at a U.S. FDA formerly approved level, for up to at least 48 hrs after withdrawal from dosing, and suggest that serum can provide an efficient matrix for monitoring FQ levels in chicken.