QuEChERS结合液相色谱-串联质谱法快速测定奶酪中多类兽药残留

建立了一种快速测定奶酪中大环内酯类、磺胺类、喹诺酮类和四环素类共50种兽药残留的分析方法。方法采用改进后的QuEChERS对奶酪进行前处理。样品在加入Na₂EDTA缓冲液和陶瓷均质子后,在5%(v/v)醋酸乙腈条件下进行振荡提取,氯化钠和无水硫酸钠用于盐析,经C₁₈吸附剂净化后,供液相色谱-串联质谱(LC-MS/MS)测定。目标化合物经ZORBAX-SB-C₁₈柱梯度分离,在正离子动态多反应监测模式下进行检测。结果表明,奶酪中50种兽药的定量限(LOQ)为0.05~20 μg/kg;在3个添加浓度(20、50、100 μg/kg)下(n=6),平均回收率在70%~120%范围内的比例分别为94%、92%和96%,相对标准偏差(RSD)为1%~14%。对市售的7个样品进行测定,其中两个样品分别检出了微量的罗红霉素和氟甲喹兽药残留。该方法快速简便,适用于奶酪中兽药残留的快速检测和日常监控。

Multi-residue determination of veterinary drugs in cheese by QuEChERS and liquid chromatography-tandem mass spectrometry

A rapid and sensitive method has been developed for the simultaneous determination of 50 veterinary drugs (including macrolides, quinolones, sulfonamides, and tetracyclines) in cheese using a modified QuEChERS method coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). After adding Na₂EDTA buffer solution and ceramic homogenizer, the cheese sample was extracted by 5% (v/v) acetic acid-acetonitrile, sodium chloride and anhydrous sodium sulfate were used for salting-out process. The resulting supernatant solution was purified by C₁₈ sorbent and the re-dissolved solution was analyzed by LC-MS/MS under dynamic multi-reaction monitoring (dynamic MRM) mode via positive electrospray ionization with a ZORBAX-SB-C₁₈ column. The limits of quantification (LOQ, S/N=10) of the target compounds ranged from 0.05 μg/kg to 20 μg/kg in cheese. At spiked levels of 20, 50, 100 μg/kg (n=6), the percentages of drug with a recovery between 70% and 120% were 94%, 92%, and 96%, respectively. The relative standard deviations (RSDs) were between 1% and 14%. This method has been applied to determine seven real samples from markets. Roxithromycin and flumequine have been detected in two samples separately. The results demonstrated that this simple, rapid and accurate method is suitable for the detection of multi-class veterinary drugs in cheese.