Gajda Anna, Posyniak Andrzej
a Department of Pharmacology and Toxicology , National Veterinary Research Institute , Pulawy , Poland.
Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2015;32(7):1116-23. doi: 10.1080/19440049.2015.1041429. Epub 2015 May 5.
The depletion of doxycycline (DC) residues in eggs was determined after oral drug administration by drinking water to laying hens. The antibiotic was supplied to birds for 5 consecutive days and the eggs were collected during medication and 18 days after withdrawal. DC residues were determined by LC-MS/MS. DC was isolated from eggs with a solution of 0.02 M of oxalic acid (pH 4), 0.1 M Na2EDTA and acetonitrile. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 2 and 5 µg kg(-1), respectively. Analyses were performed on whole egg, egg white and yolk separately. DC was detectable 24 h after the beginning of administration. The concentration of antibiotic increased daily, resulting in the highest DC concentration in whole eggs at the first day of the withdrawal period. Thirteen days after withdrawal, the content of DC in whole eggs was below the LOQ of the method. However, some differences were found in the depletion curve of DC between egg white and yolk. Residues of DC in egg white were much higher during treatment and 1 day after withdrawal, but later the concentration in egg white decreased fairly rapidly and a higher DC content in egg yolk was observed. The depletion period was shorter for egg white than for yolk, and DC was detected in the egg white until 12 days after withdrawal and 2 days more in egg yolk than in white. DC reached a peak faster in egg white, but the residues were detectable for longer period in the yolk.
通过给产蛋母鸡饮用含有强力霉素（DC）的水进行口服给药后，测定了鸡蛋中DC残留的消除情况。抗生素连续5天供应给鸡群，并在给药期间和停药后18天收集鸡蛋。通过液相色谱-串联质谱法（LC-MS/MS）测定DC残留。用0.02 M草酸（pH 4）、0.1 M Na2EDTA和乙腈的溶液从鸡蛋中分离出DC。该方法的检测限（LOD）和定量限（LOQ）分别为2和5 μg kg(-1)。分别对全蛋、蛋清和蛋黄进行分析。给药开始后24小时可检测到DC。抗生素浓度每日增加，导致停药期第一天全蛋中DC浓度最高。停药13天后，全蛋中DC含量低于该方法的LOQ。然而，蛋清和蛋黄中DC的消除曲线存在一些差异。治疗期间和停药后1天，蛋清中DC残留量高得多，但随后蛋清中浓度下降相当迅速，且观察到蛋黄中DC含量更高。蛋清的消除期比蛋黄短，停药后12天内在蛋清中可检测到DC，蛋黄中比蛋清中多检测到2天。DC在蛋清中更快达到峰值，但在蛋黄中残留可检测的时间更长。
