杜马斯燃烧法测定玉米淀粉蛋白质含量

Determination of Corn Starch Protein Content by Dumas Combustion Method

为探索杜马斯燃烧法测定玉米淀粉蛋白质含量的可行性,采用杜马斯燃烧法对3个标准物质的全氮或蛋白质含量及26个玉米淀粉样品的蛋白质含量进行测定,并与标准测定方法自动凯氏定氮仪法进行比较分析。结果表明:2种方法对标准物质的测定值均接近真实值,相对标准偏差(RSD)和相对误差(RE)杜马斯燃烧法比自动凯氏定氮仪法低;对同一玉米淀粉样品蛋白质含量多次(23次)重复测定,自动凯氏定氮仪法的测定值为0.247%~0.272%,最大值与最小值相差0.025百分点,杜马斯燃烧法测定值为0.257%~0.285%,最大值与最小值相差0.028百分点;对26个玉米淀粉样品蛋白质含量测定,2种方法测定值高度一致,RSD均小于5%;24个样品的K/D值(自动凯氏定氮仪法与杜马斯燃烧法测定值的比值)为0.951~1.055。2种方法测定玉米淀粉蛋白质含量方法稳定,精密度和准确度均较高,杜马斯燃烧法可以用于玉米淀粉蛋白质含量测定。

To explore the feasibility of Dumas combustion method to determine the protein content of corn starch,this study was conducted to examine the determination of protein content in 26 corn starch samples and protein content or total nitrogen(TN)content in three national standard substances using Dumas combustion and Kjeldahl methods,respectively.Results:The results of the two methods were close to the true value.RSD and RE of Dumas combustion method for determination of protein or TN content in three national standard substances were lower than Kjeldahl method.For the same sample’s repeated measurement(23 times),the protein content were ranging from 0.247%to 0.272%with Kjeldahl method and 0.257%to 0.285%with Dumas combustion method,and the maximum difference were 0.025%and 0.028%,respectively.For 26 corn starch samples,RSD of two methods were less than 5%and the ratio of Dumas combustion and Kjeldahl methods(D/K)was 0.951-1.055.Therefore,Dumas combustion and Kjeldahl methods are stable,precise and accurate methods for protein content determination of corn starch.Dumas combustion is applicable for the determination of protein content in corn starch.