Multiresidue determination of eleven quinolones in milk by liquid chromatography with fluorescence detection

Abstract

A liquid Chromatographic method with fluorescence detection was developed for simultaneous determination of norfloxatin, ofloxacin, dprofloxacin, pefloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxotinic acid, and flumequine in milk. The samples were extracted with 10% trichloroacetic acid/acetonitrile (9 + 1, v/v) and cleaned by Strata-X reversed-phase solid-phase extraction cartridges. The 11 quinotones were separated on a reversed-phase C18 column (Hypersil BDS-C18) with mobile phase gradient elution and detected with fluorescence by means of a wavelength program. The recoveries for milk fortified with the 11 quinolones at 3 levels were 69-88%, with acceptable relative standard deviations of <9% (intraday) and <14% (interday). The limits of detection were 23 μg/L for enrofloxacin, and 1-9 μg/L for the other 10 quinotones.