Eighty layers of 32-week-old laying hens weighing about 1.6 kg were chosen in this experiment.For test groups, the dose of sulfamonomethoxine was set at 159 mg·L-1 (label recommended maximum dose) and 79.5 mg·L-1in drinking water, respectively.After continuous medication for 5 days, the addition of sulfamonomethoxine in drinking water was stopped and eggs were collected every day.Sulfamonomethoxine residues in egg samples were pretreated with Qu ECh ERS method and quantified by ultra performance liquid chromatography-mass spectrometer/mass spectrometer (UPLC-MS/MS).The results showed that the residual amount of sulfamonomethoxine in 159 mg·L-1test group was 2 497.3, 220.1, 38.9, 6.0, 1.3, 0.5, 0.1μg·kg-1on the 1st, 3rd, 5th, 10th, 16th, 20th, 24th day, respectively.The residues of sulfamonomethoxine in 79.5 mg·L-1test group were 694.3, 45.2, 15.5, 1.5, 0.1μg·kg-1on the 1st, 3rd, 5th, 10th, 16thday, respectively.Sulfamonomethoxine depletion rate in eggs was 0.4-0.6μg·kg-1·d-1.According to the maximum residue limit (MRL) of sulfamonomethoxine in animal tissue set by China, the residual amount in eggs was lower than MRL on 5thand 3rdday in 159 mg·L-1and 79.5 mg·L-1test group, respectively, without drug application.To guarantee food safety, the proposed withdrawal period should be set at more than 5 days if the label recommended maximum dose of sulfamonomethoxine was applied.%随机选择32周龄、体质量1.6 kg的蛋鸡80羽进行试验, 在饮水中分别添加159 mg·L-1 (标签推荐最高剂量) 和79.5 mg·L-1的磺胺间甲氧嘧啶, 连续用药5 d, 分别作为高剂量组和低剂量组, 停药后收集鸡蛋样品.鸡蛋样品采用Qu ECh ERS方法进行前处理, 采用超高效液相色谱-串联质谱 (UPLC-MS/MS) 对鸡蛋样品中磺胺间甲氧嘧啶的残留量进行定量测定.结果发现, 高剂量组在休药后第1、3、5、10、16、20、24天鸡蛋磺胺间甲氧嘧啶残留量分别为2 497.3、220.1、38.9、6.0、1.3、0.5、0.1μg·kg-1, 低剂量组在休药后第1、3、5、10、16天鸡蛋磺胺间甲氧嘧啶残留量分别为694.3、45.2、15.5、1.5、0.1μg·kg-1.磺胺间甲氧嘧啶在鸡蛋中的消除速率为0.4～0.6μg·kg-1·d-1.高、低剂量组分别在停药后第5天和第3天鸡蛋中磺胺间甲氧嘧啶残留量低于国家限量标准.从食品安全角度考虑, 如采用标签推荐最高剂量, 建议休药期控制在5 d以上.
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