Quantitative determination of quinolones residues in milk by HPLC-FLD

Abstract

Veterinary drugs have become an integral part of the livestock production and play an important role in maintenance of animal welfare. The use of veterinary medicines may be cause of the presence of drug residues in animal food products if appropriate withdrawal periods are not respected or if contaminated feeds are used. This work presents the development of an HPLC-FLD method for the quantitative detection of eight quinolones -norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, difloxacin, oxolinic acid, nalidixic acid, flumequine-in bovine milk. After deproteination and extraction with a metaphosphoric acid 1% w/v / methanol / acetonitrile (60/20/20 v/v/v) solution, the sample is partially evaporated and cleaned up on a reversed phase SPE cartridge.The extract is analyzed using an high performance liquid chromatograph with fluorescence detector. Mean recovery ranged between 65% -88%. All the analytes can be identified and quantified in the concentration range 15 -60 µg/Kg for danofloxacin and 25 -150 µg/Kg for the other quinolones.