Abstract: To develop a method for simultaneous determination of 10 water-soluble vitamins (nicotinic acid, nicotinamide, vitamin B2, pyridoxine, pyridoxal, pyridoxine, pantothenic acid, biotin, folic acid and vitamin B12) in infant milk by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were dissolved in water, and adjusted to pH 1.7 with 5 mol/L HCl solution and then to pH 4.5 with 5 mol/L NaOH solution to precipitate proteins. The supernatant was added with a mixed solution of isotope internal standard, and separated on an ACQUITY UPLC HSS T3 column (2.1 mm × 50 mm, 1.8 μm) by gradient elution using a mobile phase composed of 10 mmol/L ammonium formate aqueous solution (containing 0.1% formic acid) and 10 mmol/L ammonium formate methanol solution (containing 0.1% formic acid). Detection was performed by electrospray ionization in the positive ion mode with multiple reaction monitoring (MRM). The external standard method was used for the quantification of pyridoxine, pyridoxal and pyridoxine, and the internal standard method for the other seven vitamins. Good linearity of the calibration curves for the 10 water-soluble vitamins was obtained in the range of 10–5 000 ng/mL with correlation coefficients (R2) above 0.99, and the recoveries for spiked samples ranged from 73.9% to 106.0%, with relative standard deviations (RSDs) of 0.9%–8.0%. The proposed method is simple, rapid, sensitive and accurate, and can meet the requirements for the determination of the 10 water-soluble vitamins in infant formula.

Key words: infant formula; water-soluble vitamin; ultra performance liquid chromatography-tandem mass spectrometry; internal standard method; external standard method

摘要： 建立超高效液相色谱-串联质谱法同时测定婴幼儿配方乳粉中10 种水溶性维生素（烟酸、烟酰胺、VB2、吡哆醇、吡哆醛、吡哆胺、泛酸、生物素、叶酸和VB12）的方法。样品用水溶解后，先用5 mol/L盐酸溶液调节pH值至1.7，再用5 mol/L NaOH溶液调节pH值至4.5，以沉淀蛋白质，然后加入混合同位素内标溶液，经ACQUITYUPLC HSS T3色谱柱（2.1 mm×50 mm，1.8 μm）分离，以10 mmol/L甲酸铵水溶液（含0.1%甲酸）和10 mmol/L甲酸铵甲醇溶液（含0.1%甲酸）为流动相梯度洗脱，电喷雾电离正离子模式下以多反应监测方式检测，除了吡哆醇、吡哆醛、吡哆胺采用外标法定量外，其他7 种维生素采用内标法定量。结果表明：10 种水溶性维生素在质量浓度10～5 000 ng/mL具有良好的线性关系，相关系数（R2）大于0.99，加标回收率为73.9%～106.0%，相对标准偏差为0.9%～8.0%。该方法简便、快速、灵敏、准确，可满足婴幼儿配方乳粉中10 种水溶性维生素的检测要求。

关键词: 婴幼儿配方乳粉；水溶性维生素；超高效液相色谱-串联质谱法；内标法；外标法