Validation of a Method for the Analysis of Nine Quinolones in Eggs by Pressurized Liquid Extraction and Liquid Chromatography with Fluorescence Detection

A multiresidue method for the analysis, in egg matrices, of residues of nine quinolones used in veterinary medicine, has been developed and validated according to the provisions of Council Decision 2002/657. Compounds were extracted by a pressurized liquid extraction (PLE) technique using a 1:1 mixture of acetonitrile and a phosphoric acid buffer (pH 3.0) at 70°C. The obtained extract was clear enough, so that no further clean-up was necessary. Analytes were determined by liquid chromatography (LC) with fluorescence detection (FL). Two chromatographic columns were compared: a high-purity silica Inertsil C(8) column and a newly developed Kinetex C(18) core-shell technology column. Validation was carried out at four concentration levels, using both chromatographic columns. Precision in terms of reproducibility standard deviation was between 7% and 23%, and good recoveries were obtained. Decision limit (CCα) and detection capability (CCβ) values obtained with the Inertsil and Kinetex columns were in the 0.2-19.8 μg kg(-1) and 0.4-33.5 μg kg(-1) concentration ranges, respectively. The proposed method allows residues of quinolones banned for use with laying hens to be detected and quantified in eggs. About twenty-four samples per day can be processed.