Determination of Antibiotics Residues in Milk Using a QuEChERS Method Using Full Factorial Design and Liquid Chromatography-Tandem Mass Spectrometry

This study evaluated different methods of extraction based on quick, easy, cheap, effective, rugged and safe (QuEChERS) method for analysis of the antibiotics ceftiofur, cloxacillin and enrofloxacin in milk using ultra-performance liquid chromatography-tandem mass spectrometry. The QuEChERS acetate method has been shown to be inefficient for extracting such antibiotics. The optimized QuEChERS method presented excellent recoveries, from 95 to 99%. A complete factorial design was used to evaluate the effects of variables of the clean-up step: anhydrous octadecylsilane (C18), primary secondary amine (PSA) and sodium acetate (NaAc). Linearity (R2) above 0.96 was achieved for all compounds. Accuracy and precision were assessed by recovery. Accuracy was 91-99%. Intraday precision with relative standard deviations (RSD) lower than 12.3% and interday precision lower than 12.4% were obtained. Limits of detection (LOD) and quantification (LOQ) were obtained between 1.4-6.8 and 1.5-8.7 µg L-1, respectively. The applicability was evaluated using 91 real milk samples.

本研究以超高效液相色谱-串联质谱法（ultra-performance liquid chromatography-tandem mass spectrometry）为分析手段，针对牛奶中头孢噻呋（ceftiofur）、氯唑西林（cloxacillin）与恩诺沙星（enrofloxacin）三种抗生素的检测，评估了多款基于快速、简便、廉价、高效、耐用且安全（QuEChERS）方法的提取方案。已有研究证实，传统QuEChERS乙酸盐法对这类抗生素的提取效率不佳。经优化后的QuEChERS方法回收率优异，可达95%~99%。本研究采用全因子析因设计，对净化步骤的变量效应进行了考察：无水十八烷基硅烷（C18）、伯仲胺吸附剂（PSA）与乙酸钠（NaAc）。所有目标化合物的线性相关系数（R²）均高于0.96。本研究通过回收率实验评估了方法的准确度与精密度：方法准确度介于91%~99%之间；日内精密度的相对标准偏差（RSD）低于12.3%，日间精密度的RSD低于12.4%。检出限（LOD）与定量限（LOQ）分别为1.4~6.8 µg·L⁻¹与1.5~8.7 µg·L⁻¹。本研究采用91份实际牛奶样本对该方法的适用性进行了验证。