Depletion of florfenicol and florfenicol amine residues in chicken eggs

1. The aim of this study was to develop a suitable method for the analysis of florfenicol (FF) and its metabolite florfenicol amine (FFA) in chicken eggs and to determine FF and FFA residue depletion in eggs of laying hens.2. The analytes were extracted from yolk, albumen and whole egg by phosphate buffer and ethyl acetate. Following purification, samples were analysed by high-performance liquid chromatography.3. Fifty laying hens were divided into 5 groups, and each hen received doses of 20 mg/kg FF: Group 1 (received a single oral dose by gavage); Group 2 (a single intramuscular dose); Group 3 (a single subcutaneous dose); Group 4 (multiple oral doses for 3 d) and Group 5 (multiple oral doses for 5 d).4. Limits of detection and of quantitation values were 1.94 and 6.45 g/109 g (ppb) for FF, respectively, and 0.48 and 1.58 ppb for FFA, respectively. Relative standard deviation values of intra-day and inter-day variation below 11% also confirmed the usefulness of the method for analysing FF and FFA in eggs.5. From the first day of both oral and parenteral administration, FF and FFA were detected at 0.1% and 0.08% of dosage, respectively, and 57% of the drugs were eliminated from the egg yolk. Elimination time of FF was 8 d in Groups 1, 2 and 3; 9 d in Group 4 and 10 d in Group 5.1. 本研究旨在建立一种适用于鸡蛋中氟苯尼考（florfenicol, FF）及其代谢物氟苯尼考胺（florfenicol amine, FFA）的分析方法，并测定产蛋鸡鸡蛋内氟苯尼考及氟苯尼考胺的残留消除规律。 2. 采用磷酸盐缓冲液与乙酸乙酯对蛋黄、蛋清及全蛋中的目标分析物进行提取；经净化处理后，采用高效液相色谱法（high-performance liquid chromatography）对样品进行分析。 3. 将50只产蛋鸡分为5组，每只鸡按每千克体重20 mg的剂量给予氟苯尼考：第1组采用单次灌服给药；第2组采用单次肌内注射给药；第3组采用单次皮下注射给药；第4组连续3日口服给药；第5组连续5日口服给药。 4. 氟苯尼考的检测限与定量限分别为1.94与6.45 g/109 g（ppb），氟苯尼考胺的检测限与定量限分别为0.48与1.58 ppb。日内与日间相对标准偏差均低于11%，证实了该方法用于鸡蛋中氟苯尼考及氟苯尼考胺分析的适用性。 5. 自口服与胃肠外给药首日起，即可检出占给药剂量0.1%的氟苯尼考与0.08%的氟苯尼考胺，且蛋黄中已有57%的药物被消除。第1、2、3组中氟苯尼考的消除时长为8 d，第4组为9 d，第5组为10 d。