微波消解-恒pH滴定法快速测定粮食中的粗蛋白

RAPID DETERMINATION OF CRUDE PROTEIN IN GRAIN WITH CONSTANT pH METHOD BY MICROWAVE DIGESTION

为建立一种快速测定食品中粗蛋白质的新型分析方法，选择小麦为样品，用硫酸一过氧化氢混合溶液为消解剂，利用微波压力程序加热技术快速消解样品，用甲醛法将NH4^＋转化为H^＋，以KOH为标准溶液，用恒pH滴定法进行测定。结果表明：小麦干基粗蛋白的含量在14％～17％之间，RSD1．2％～2．1％（n=6或12）。与经典方法对照测定，经F检验和t检验表明两者之间无显著性差异（置信度95%）。该法操作简单、快速，试剂用量少，空白值低，工作效率大大提高，结果令人满意。

In order to establish a rapid analysis method of determination crude protein in food, we selected wheat as samples, which were digested with sulfuric acid -- hydrogen peroxide mixture solution, using the microwave pressure procedure heating technology for rapid digestion samples, using formaldehyde method which changed NH4^＋ into H^＋, and KOH as the standard solution, wheat samples were determinated by constant pH titration method. The results indicated that the content of crude protein in dry wheat is 14- 17%, the relatively standard deviation is 1.2% - 2.1% （n = 6 or 12）. The results compared with the classic Kjeldahl determination method showed that there was no significant differenee between them （95% confidence level） by the F-test and t-test. This method is simple, quick, less reagents consumption, low gap values and can improve the efficiency of work greatly, the result is satisfactory.