婴幼儿配方奶粉中肌醇的测定及稳定性研究

Determination and stability research of myo-inositol in infant milk powder

建立了毛细管气相色谱-内标法测定婴幼儿配方奶粉中肌醇质量分数的方法。肌醇被体积分数为70%乙醇提取后,加入山梨醇为内标,经衍生试剂衍生,用正己烷萃取,采用氢火焰检测器(FID)的气相色谱仪检测。结果表明,肌醇的回收率是98.42%~100.97%,相对标准偏差(RSD)为0.54%~1.23%,线性范围在0~500μg之间,检出限为0.72 mg/100g。本方法可有效地减少基质中杂质的干扰,提高检测的准确性,与国标方法相比无显著性差异,适用于婴幼儿配方奶粉中肌醇质量分数的分析测定。同时采用本方法跟踪测定了婴幼儿配方奶粉开封后180 d内肌醇质量分数的变化情况,分析肌醇在婴幼儿配方奶粉中的稳定性。结果表明,肌醇质量分数随时间的延长而降低,在高温(37℃)存放时损失最快。

A method using gas chromatography （GC） with internal standard was established for the determination of myo-inositol in infant milk powder. Samples were extracted with 70% ethanol, add sorbitol as internal standard, the resulting extract was derived with derivatization reagent, then the N-Hexane was used to extract the derived myo-inositol, and the results were determined by GC with a hydrogen flame ionization detector （FID）. The results showed that the average recoveries for myo-inositol were ranged from 98.42% to 100.97%, with the relative standard derivation （RSD） ranging from 0.54% to 1.23%. The linear range was from 0 to 500 μg and the detection limit of the method was 0.72 mg/100 g. The method had higher repeatability and reduced the matrix interference to improve the accuracy of the results, and there were no significant difference between this method and GB 5413.25-2010, which could satisfy the demand on the determination of myo-inositol infant milk powder. The stability of infant milk powder in the storage process after opened to store for 180 days was affected by the external environment, and the content of myo-inositol decreased with the time passing and reduced fastest on high temperature （37℃ ）.