前处理对液相色谱法测定婴幼儿配方奶粉中维生素C含量的影响

Effect of pretreatment on determination of vitamin C in infant formula by liquid chromatography

中文关键词:  液相色谱法  婴幼儿配方乳粉  维生素C  前处理

英文关键词:liquid chromatography  infant formula  vitamin C  pretreatments

中文摘要:

      目的 研究液相色谱操作条件、标准溶液配制及保存、样品提取等前处理对液相色谱法测定婴幼儿配方奶粉中维生素C含量的影响。方法 测定不同流动相下维生素C峰面积及保留时间; 比较不同酸性溶液配制的标准溶液保存一定时间后峰面积的变化; 用不同浓度的乙酸溶液作为提取液, 在不同水浴温度、超声时间下对奶粉样品进行提取, 测定其峰面积。结果 样品溶液在0.05 mol/L磷酸二氢钾(pH=3.0)甲醇流动相下, 经TechMate ST-C18色谱柱分离, 在245 nm条件下进行检测, 可获得较大的响应值及合适的保留时间。维生素C的最佳提取条件为: 提取液为1%乙酸溶液、水浴温度不宜超过20 ℃、提取时超声时间为20 min。采用确定的条件对婴幼儿配方奶粉中维生素C含量进行测定, 维生素C在1~100 mg/L范围内线性良好, r2大于0.999。加标回收率在76.5%~91.4%之间, RSD在5%以下。结论 本研究建立的前处理方法能够满足维生素C的测定要求。

英文摘要:

      Objective To study effect of pretreatments (liquid chromatography (LC) operating condition, standard solution preparation and preservation, sample extraction) on the determination of vitamin C in infant formula by LC. Methods The peak area and retention time of vitamin C in different flow phases were measured. The changes in the peak area of standard solution prepared by different acid solutions after preserved a certain time were compared. The sample was extracted under different water bath temperature and ultrasonic time with different concentration of acetic acid solution as the extract, and the peak area was determined. Results With 0.05 mol/L KH2PO3 (pH=3.0)-methanol as mobile phase, samples were separated by TechMate ST-C18 chromatographic column and detected at 245 nm, which could obtain the larger response value and suitable retention time. The best condition of vitamin C were as follows: extract solution was 1% acetic acid, bath temperature was less than 20 ℃, ultrasonic time was 20 min. The vitamin C content in infant formula milk powder was determined, it had good linear in the range of 1~100 mg/L, and the correlation coefficients were more than 0.999. The spiked recoveries were 76.5%~91.4%, with the relative standard deviations under 5%. Conclusion The pretreatment method can meet the requirement for the determination of vitamin C.