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item Schneider, Marilyn
item Vazquez Moreno, Luz
item Barraza Guardado, Ramon
item Ortega-nieblas, Magdalena

Submitted to: Journal of the Association of Official Analytical Chemists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2005
Publication Date: 8/1/2005
Citation: Schneider, M.J., Vazquez Moreno, L., Barraza Guardado, R., Ortega-Nieblas, M. 2005. Multiresidue determination of fluoroquinolone antibiotics in shrimp by liquid chromatography-fluorescence-mass spectrometry. Journal of the Association of Official Analytical Chemists. 88. pp. 1160-1166.

Interpretive Summary: Fluoroquinolone antibiotics are effective against a wide range of bacteria and are currently used in both medical and veterinary applications. Use of these antibiotics in animals intended for food production has generated concern as the presence of these residues in food may lead to increased microbial resistance in humans. Thus efficient multiresidue methods are required to detect, measure levels of, and confirm the identity of fluoroquinolones in edible animal tissue. We have now developed a method which allows for the simultaneous detection, measurement, and confirmation of 8 fluoroquinolones in shrimp tissue. This approach uses liquid chromatography with fluorescence detection to detect and sensitively measure levels of fluoroquinolones present, and mass spectrometry(n) to provide confirmation, taking advantage of the strengths of both techniques. With this method, we have successfully recovered, measured, and confirmed the identities of 8 fluoroquinolones from fortified shrimp tissue. The method was also successful in analysis of fluoroquinolones from shrimp incurred with the fluoroquinolone enrofloxacin. This efficient and sensitive multiresidue method allows both measurement and confirmation and provides a valuable tool for regulatory agencies.

Technical Abstract: An efficient multiresidue method for analysis of fluoroquinolones in shrimp has been developed in which quantitation by fluorescence and confirmation by MSn is achieved simultaneously. In this method, shrimp tissue is extracted with ammoniacal acetonitrile, the extract defatted, and then evaporated. After dissolution in basic phosphate buffer, fluoroquinolones in the extract are separated by liquid chromatography and quantitated, taking advantage of their intense fluorescence. Eluate from the fluorescence detector enters the MSn, which allows for confirmation by monitoring ratios of two prominent product ions in the MS3 or MS2 spectrum. Using this method, 8 fluoroquinolones have been analyzed in shrimp samples fortified at 10, 25, 50 or 100 ppb levels. Recoveries for desethylciprofloxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, orbifloxacin, sarafloxacin and difloxacin ranged from 75-92%, with RSDs < 6%. The limits of quantitation ranged from 0.1-1 ng/g. Enrofloxacin and ciprofloxacin were also successfully determined in enrofloxacin incurred shrimp using this method.