Salting-Out Assisted Liquid-Liquid Extraction Coupled to UPLC-MS/MS for Determination of Tetracyclines in Milk Powder(盐析液液萃取-超高效液相色谱-串联质谱法测定奶粉中四环素类抗生素)
摘要
The use of salting-out assisted liquid-liquid extraction (SALLE) combined with UPLC-MS/MS has been evaluated for the determination of tetracyclines in milk powder. The samples were extracted with Na<sub>2</sub>EDTA-Mcllvaine buffer, and then the target analytes were extracted with acetonitrile assisted with (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>. After concentrated, the target analytes were separated on a BEH C18 column with gradient elution using acetonitrile and water containing volume fraction 0.1% formic acid as mobile phase. MS detection was performed with the positive ion mode in multi-reaction monitoring. The samples were quantified with external standard method. The result showed that, under the assisted with (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, the extraction and purification effect of acetonitrile was improved. The limit of detection was 0.36μg/kg, which was much lower than 50μg/kg for the solid-phase extraction method. The linear range was from 1 to 100μg /kg with the correlation coefficient R>0.999. The recoveries of the method were ranged from 71.88% to 107.13% at the spiked levels of 1,5, 50μg/kg and the relative standard deviation was less than 8%. This method was simple, sensitive, economical, reliable and environmentally friendly. The method was suitable for the qualitative and quantitative of tetracyclines in milk powder.(建立了盐析液液萃取-超高效液相色谱-串联质谱法检测婴儿配方奶粉中四环素、土霉素、金霉素和强力霉素4种四环素类抗生素的方法。奶粉样品经Na<sub>2</sub>EDTA-Mcllvaine缓冲液提取,在硫酸铵辅助下采用少量乙腈萃取浓缩后,以体积分数0.1%甲酸水溶液和乙腈为流动相梯度洗脱,经BEH C18柱分离,ESI+电喷雾模式扫描,MRM多反应模式检测,外标法进行定量。结果显示,在硫酸铵作用下,乙腈对目标化合物的提取净化效果较好；该方法下4种四环素类抗生素的最低检出限为0.36μg/kg,远远低于国标固相萃取法的50μg/kg；质量浓度为1～100ng/mL时,4种化合物的线性相关性好,相关系数都在0.9990以上；加标浓度为1、5、50μg/kg时的回收率为71.88%~107.13%,相对标准偏差都小于8%。研究结果可为婴儿配方奶粉中四环素类抗生素的定性定量分析提供参考。)