Determination Of Residues Of Decoquinate In Food Of Animal Origin

Decoquinate is a quinolone anticoccidial drug, developed by may&mark company in the early1970s, and was introduced in China in2006. It was widely used for the prevention and treatment of coccidiosis, due to its excellent actively against coccidia soft capsule.Although decoquinate has been widely used since1967in many countries, it has never been used in China and has little drug-resistance problems. So it is still used worldwide to prevent the coccidiosis in broiler chickens, but it was banned in Legehenne. The Ministry of Agriculture China and Japan Ministry of Health Labour Welfare have reported recommended maximum residue limits (MRLs) in edible tissues. Little is known about the absorption of orally administered decoquinate, and it was metabolized mainly in the form of parent compound with3other components occurring in rats. Today, several analytical methods are available for the determination of decoquinate in the tissues, but no formal residues studies have been carried out using the recommended dosage regime.The aim of the present study is to develop a rapid、sensitive and reliable LC-MS/MS method for the determination of decoquinate in edible tissues (muscle、liver) and egg, and applied to the depletion study of decoquinate in tissues. The results are as following:1. Development of a LC-MS/MS method for the determination of decoquinate in Chicken tissuesA rapid、sensitive and reliable LC-MS/MS method for the determination of decoquinate in muscle and liver samples is developed and validated. Analyte is effectively extracted by acetonitril using liquid-liquid extraction, and purified by HLB column. Chromatography separation is performed on a C18reversed-phase column with the mobile phase of water containing0.1%formic acid-acetonitrile. The analyte is detected by multiple reaction monitoring (MRM). The limit of detection and limit of quantification are1μg/kg and2.5μg/kg, respectively. The recoveries range from85.3%to104.9%when spiked with diffenent levels of analyte, with relative standard deviations generally below10.4%. 2. Development of a LC-MS/MS method for the determination of decoquinate in eggsA rapid and sensitive LC-MS/MS method for the determination of decoquinate in egg samples is developed and validated. Analyte is effectively extracted from sample by acetonitril-ethyl acetate and the extraction is passed through HLB column for further purification. Limits of detection and quantification for analyte are0.2μg/kg and0.8μg/kg, respectively, and the analyte has a good linearity at the range of0.8～240μg/kg, with related coefficient of R2>0.993. The recoveries range from90.7%to101.8%when spiked with diffenent levels of analyte, with relative standard deviations generally below11.4%.3. Residue depletion study of decoquinate in edible tissues and eggsThe developed method in this study is successfully applied to residue depletion study of decoquinate in edible tissues and egg. The animals are oral administrated of feed containing27.2ppm decoquinate for10consecutive days, and samples collected at different days are detected using the proposed method. The recommended withdrawal time based this experiment is3days in broiler chickens, and it is not detected in11days in eggs.In conclusion, a rapid, simple, sensitive and reliable LC-MS/MS method for the determination of decoquinate in edible tissues and egg was developed. The method satisfactory was validated with respect to specificity, sensitivity, accuracy, precision and stability. And, the method is successfully applied to residue depletion study.