关于GB 29989-2013《婴幼儿食品和乳品中左旋肉碱的测定》几个关键步骤的探讨研究

目的探讨影响国家标准GB29989-2013《婴幼儿食品和乳品中左旋肉碱的测定》测定结果准确性的因素。方法研究样品前处理过程中pH调节方式,乙酰肉碱转移酶的配制,待测液静置时长,特殊基质前处理方法优化,酶反应过程避光与否等方面对测定结果的影响。结果 pH调节对结果准确性影响较大,待测液静置2h检测结果与过夜后恢复室温检测结果基本无差异,特殊医学用途配方食品加入高氯酸后无法直接沉淀过滤,酶反应过程需是否避光对检测结果有较大影响。结论测定过程中pH调节不可回调,待测液静置2 h后可直接检测,特殊医学用途配方乳粉前处理时应先加入α-淀粉酶水解,酶反应过程需避光。

Discussion on several key steps of GB 29989-2013 Determination of L-carnitine in food and dairy products for infants and young children

Objective To explore the factors influencing the accuracy of national standard GB 29999-2013 Determination of L-carnitine in food and dairy products for infants and young children. Methods The influence of pH regulation, the preparation of acetyl carnitine transferase, the standing time of the solution to be measured, the optimization of the pretreatment method of special substrate, and the avoidance of light during the enzyme reaction on the determination results were studied. Results The pH adjustment had a great influence on the accuracy of the results. There was basically no difference between the test results after 2 h standing and the test results after overnight. The formula foods for special medical purposes could not be directly precipitation filtration after adding perchloric acid, and whether the enzyme reaction process needed to be protected from light had a great influence on the detection results. Conclusion During the determination process, the pH can not be adjusted back, and the test solution can be directly detected after standing for 2 h. Alpha-amylase hydrolysis should be added to the pre-treatment of formula milk powder for special medical purposes. The enzyme reaction needs to be light-proof.