Abstract: An ultra-high performance liquid chromatography method was established for the determination of citric acid in dairy products. The samples were precipitated by K3Fe(CN)6 and (CH3COO)2Zn, then extracted by ultrasound, cryogenically frozen and centrifuged to precipitate protein and fat,.The chromatographic separation was accomplished with Poroshell 120 Aq-C18 (2.7μm 4.6×100mm) using gradient elution with a mobile phase consisting of a mixture of methanol and ammonium dihydrogen phosphate solution.The samples were detected by UV detector and quantified by external standard method. The results showed that the standard curve was linear, the correlation coefficient was above 0.9999, the average recovery was 95.2%-101.0%, the detection limit was 100 mg/kg, and the relative standard deviation was 1.08%-2.22%. The method is simple, rapid and has good separation effect. It is suitable for the quantitative analysis of citric acid in milk and dairy products.

Key words: citric acid, Ultra-high performance liquid chromatography (UPLC), Sterilized milk, Fermented milk, Dairy products.

摘要： 建立超高效液相色谱方法测定如及乳制品中柠檬酸的含量。样品经亚铁氰化钾和乙酸锌沉淀，超声提取，低温冷冻离心沉淀蛋白脂肪，取上清液，Poroshell 120 Aq-C18 （2.7μm 4.6×100mm）分离，以磷酸二氢铵溶液-甲醇为流动相进行梯度洗脱，运用紫外检测器进行检测，外标法定量。结果表明：标准曲线线性良好，相关系数在0.9999以上，平均加标回收率为95.2%～101.0%,检出限为100 mg/kg，相对标准偏差为1.08%～2.22%。该方法简便、快速、分离效果好，适用于乳及乳制品中柠檬酸的定量分析

关键词: 柠檬酸, 超高效液相色谱（UPLC）, 灭菌乳, 发酵乳, 乳制品