Fast and selective determination of total protein in milk powder via titration of moving reaction boundary electrophoresis
Fast and selective determination of total protein in milk powder via titration of moving reaction boundary electrophoresis
复制标题
移动反应边界电泳滴定法快速、选择性测定奶粉中的总蛋白
DOI：
10.1002/elps.201300007
复制
发表时间：
2013-05-01
期刊：
影响因子：
2.9
通讯作者：
Cao, Cheng-xi
中科院分区：
文献类型：
--
作者：
Guo, Cheng-ye;Wang, Hou-yu;Cao, Cheng-xi
本文从移动反应边界（MRB）电泳的概念出发，建立了移动反应边界滴定法（MRBT），用于快速、准确地测定婴幼儿奶粉中的总蛋白。在该方法中，MRB由通过交联聚丙烯酰胺凝胶（PAG）固定的乳蛋白的氢氧根离子和酸性残基形成，用酸碱指示剂指示边界运动。作为概念验证，我们选择了五个品牌的婴儿奶粉，研究MRBT方法的可行性。基于MRB运动的视觉信号作为对数乳蛋白含量的函数，建立了婴儿奶粉样品的MRB速度与对数总蛋白含量的校准曲线。非蛋白氮（NPN）试剂（例如，三聚氰胺和尿素）对MRBT方法的影响，这是由于MRB是由氢氧根离子和捕获的乳蛋白的酸性残留物形成的，而不是碱性残留物或添加的NPN试剂。用MRBT法检测婴幼儿奶粉中总蛋白含量与经典凯氏定氮法结果一致。与凯氏定氮法相比，该方法具有更快的测定速度。
In this paper, moving reaction boundary titration (MRBT) was developed for rapid and accurate quantification of total protein in infant milk powder, from the concept of moving reaction boundary (MRB) electrophoresis. In the method, the MRB was formed by the hydroxide ions and the acidic residues of milk proteins immobilized via cross‐linked polyacrylamide gel (PAG), an acid‐base indicator was used to denote the boundary motion. As a proof of concept, we chose five brands of infant milk powders to study the feasibility of MRBT method. The calibration curve of MRB velocity versus logarithmic total protein content of infant milk powder sample was established based on the visual signal of MRB motion as a function of logarithmic milk protein content. Weak influence of nonprotein nitrogen (NPN) reagents (e.g., melamine and urea) on MRBT method was observed, due to the fact that MRB was formed with hydroxide ions and the acidic residues of captured milk proteins, rather than the alkaline residues or the NPN reagents added. The total protein contents in infant milk powder samples detected via the MRBT method were in good agreement with those achieved by the classic Kjeldahl method. In addition, the developed method had much faster measuring speed compared with the Kjeldahl method.