高效液相色谱法测定婴儿配方奶粉中乳糖和蔗糖含量的前处理方法优化

目的优化GB 5413.5-2010《食品安全国家标准婴幼儿食品和乳品中乳糖、蔗糖的测定》(第一法)中前处理步骤。方法样品先用15 mL热水溶解,再加入乙酸锌、亚铁氰化钾溶液各2 mL,涡旋振荡超声,加水定容到50 mL,离心过滤,最终通过高效液相色谱仪测定。结果测定乳糖含量较低的样品时,国标测定的结果与本方法相近,2种方法的相对标准偏差为0.22%。国标方法的样品加标回收率为99.0%,本方法为99.7%。本方法样品重复6次,蔗糖重复性的相对标准偏差为0.593%,乳糖为1.24%。当国标方法测定乳糖含量较高的样品时,会出现糖析出的问题,测得乳糖的含量远低于本方法。结论本方法解决了国标前处理出现的样品糖析出问题。研究结果表明本方法的精密度高、准确度高,线性范围良好,操作简单,是测定婴儿配方奶粉中蔗糖和乳糖含量的有效方法。

Optimization of pretreatment method for determination of sucrose and lactose in infant formula by high performance liquid chromatography

Objective To optimize the pretreatment steps in GB 5413.5-2010 National food safety standard-Determination of lactose and sucrose in foods for infants and young children, (method 1). Methods The sample was first dissolved in 15 mL of hot water, then 2 mL zinc acetate and 2 mL potassium ferrocyanide solutions were added, vortexed and sonicated, after adding water to 50 mL, the solution was centrifuged, and finally detected by high-performance liquid chromatography. Results For samples with low lactose content, the result of national standard method was similar to that of this method, with a relative standard deviation of 0.22%. The recovery rate of spiked samples was 99.0% in national standard and 99.7% in this method. This method was repeated for 6 times with the relative standard deviation of sucrose reproducibility of 0.593% and lactose of 1.24%. When the national standard method was used to determine samples with high lactose content, the problem of sugar precipitation would occur, and the measured lactose content was far lower than that of this method. Conclusion The problems of turbidity and sugar precipitation in the pretreatment process in the national standard are solved. The results show that this method has high precision, high accuracy, good linear range and simple operation, which is an effective method for the determination of sucrose and lactose in infant formula milk powder.