Capolongo Francesca, Santi Annalisa, Tomasi Luciana, Anfossi Paola, Missagia Mauro, Montesissa Clara
Università degli Studi di Padova, Istituto di Patologia e Igiene Veterinaria, Agripolis Legnaro Padova, Italy.
J AOAC Int. 2002 Jan-Feb;85(1):8-14.
Residues of oxytetracycline (OTC) in edible tissues (muscle, liver, and kidney) of 18 turkeys were determined after continuous administration of the drug for 3 days in drinking water at the maximum recommended concentration of 400 mg/L. The European Union (EU) maximum residue limits (MRLs) set for OTC are 100 microg/kg in muscle tissues, 300 microg/kg in liver, and 600 microg/kg in kidney, as the sum of the parent compound and its derivative 4'-epi-oxytetracycline (4-epi-OTC). Cleanup of tissue samples was performed by metal chelate affinity chromatography (MCAC), but the original technique was miniaturized by the adoption of a mini solid-phase extraction column, allowing reduction of solvents, time, and hazardous waste. OTC and its 4'-epimer were quantitated by an isocratic liquid chromatography elution with UV detection. After 1 day of withdrawal, OTC plus 4-epi-OTC residues were greater than MRL values in muscle and liver; 3 days after the end of treatment, all tissue residues were far lower than the MRL values. At the first day after the end of treatment, 4-epi-OTC was detected at very low concentrations only in muscle, in liver after 1 and 3 days of withdrawal, and in kidney at all sampling times. The withdrawal time was calculated according to EU recommendations and was set at 5 days.
在以400 mg/L的最大推荐浓度通过饮水连续给药3天后，测定了18只火鸡可食用组织（肌肉、肝脏和肾脏）中土霉素（OTC）的残留量。欧盟（EU）为OTC设定的最大残留限量（MRLs）为：肌肉组织中100微克/千克，肝脏中300微克/千克，肾脏中600微克/千克，以母体化合物及其衍生物4'-表土霉素（4-表-OTC）的总和计。组织样品的净化通过金属螯合亲和色谱法（MCAC）进行，但采用微型固相萃取柱使原始技术小型化，从而减少了溶剂、时间和有害废物。OTC及其4'-差向异构体通过等度液相色谱洗脱并紫外检测进行定量。停药1天后，肌肉和肝脏中OTC加4-表-OTC的残留量高于MRL值；治疗结束3天后，所有组织残留量均远低于MRL值。在治疗结束后的第一天，仅在肌肉中以极低浓度检测到4-表-OTC，在停药1天和3天后在肝脏中检测到，在所有采样时间的肾脏中均检测到。停药时间根据欧盟建议计算并设定为5天。
