钙离子选择性电极法测定饮料中游离钙含量的影响因素及其应用

Application and Influencing Factors on the Content of Free Calcium in Beverage of Ca^(2+) Selective Electrode Method

目的:钙离子选择性电极法研究饮料中游离钙含量的影响因素及其应用。方法:配制不同浓度钙离子溶液并测定电位值,制作电极的校准曲线,应用该方法测定多种饮料、奶粉及乳清粉中游离钙的含量,并研究饮料中游离钙的回收率、离心对游离钙含量测定以及回收率测定的影响、研究p H值、磷酸盐或柠檬酸盐、多糖对饮料中游离钙含量的影响。结果:钙离子溶液的电位值与浓度的对数值之间呈现较高的线性相关,相关系数达0.99以上,应用校准曲线测定钙离子溶液时回收率达98.4%~100.5%,可以用于高低不同浓度游离钙含量的测定;测定饮料游离钙时离心与否不影响游离钙含量的测定,同时,由于存在螯合剂以及脂肪酸等物质回收率将明显偏低;pH、不同盐及不同盐的浓度、不同多糖明显影响饮料中游离钙的含量。结论:钙离子选择性电极法可以用于饮料及奶粉等粉末样品中游离钙含量的测定,同时,用于饮料中游离钙含量的各种影响因素的研究。

Objective：To study the application and influencing factors on the content of free calcium in beverage of calcium ion selective electrode method.Method：The calibration curves for the electrode were ob-tained by determining the potential values of different concentrations of calcium ion solution prepared.Apply-ing this method the contents of free calcium in several kinds of beverages,milk powder and whey protein were determined.In addition,the recovery of free calcium in beverage,the effect of centrifugation on the content of free calcium and the recovery as well as the effects of pH,phosphate or citrate and polysaccharides on the free calcium content in beverages were discussed.Result：The linear correlation between the potential value and the concentration was higher with more than 0.99 of the correlation coefficient and the recovery of 98.4%~100.5%when applied to determine in the Ca2＋solution,which could be used to determine the content of free calcium in different concentrations from lower to higher.The centrifugation didn’t affect the determination of free calcium content and due to the presence of chelating agents and fatty acids the recovery was significantly lower in beverage.Moreover,pH,different salts and their concentration and different polysaccharides signifi-cantly affected the content of free calcium in beverage.Conclusion：Calcium ion selective electrode method could be used to determine the content of free calcium in beverages and powders like milk powder and study the varied influencing factors which effect on the free calcium in beverage.