【摘要】 提出了一种有效去除三聚氰胺等非蛋白氮干扰的凯氏定氮法测定牛奶中真蛋白质的含量的方法。在5mL样品中加入甲醛3 mL,漩涡混匀1 min,于70℃水浴加热10 min后,加入150g·L-1三氯乙酸溶液5mL沉淀蛋白质,抽滤分离后,应用自动凯氏定氮仪测定沉淀中的蛋白质含量。经配对t检验分析,本法与国家标准方法测定牛血清白蛋白标准溶液中蛋白质含量、与考马斯亮蓝G-250法测定牛奶中真蛋白质含量以及干扰试验中各干扰物添加组与对照组中蛋白质含量的测定结果均无显著性差异。被分离的滤液中干扰物的回收率在98.4%~100%之间。更多还原

【Abstract】 A new Kjeldahl nitrogen method for the determination of true protein in milk which could effectively remove the interference of melamine and other non-protein nitrogen was proposed.3mL of formaldehyde was added into 5mL samples,then the mixture was vortexed for 1min and heated in 70 ℃ water bath for 10 min.5mL of 150g·L-1 trichloroacetic acid solution was added to precipitate proteins.After filtration,proteins in the precipitate were measured by automatic Kjeldahl nitrogen analyzer.The data found was analyzed using paired t-test and showed.No significant difference between bovine serum albumin standard solution determined by this method and the GB method,between true protein in milk determined by this method and Coomassie brilliant blue G-250 method,between protein of interference group and control group in interference test.Values of recovery of disruptors in filtrate found was in the range of 98.4%-100%.更多还原