ISO 5983-2:2009规定了根据凯氏定氮法测定动物饲料的氮含量的方法，以及计算粗蛋白质含量的方法。 适用于使用块状消解，铜催化剂和蒸汽蒸馏成硼酸的半微速快速常规方法。 该方法适用于动物饲料，宠物食品及其原料中大于0.5％质量分数凯氏定氮的测定。 该方法不测量氧化形式的氮和杂环氮化合物。 该方法不区分蛋白质氮和非蛋白氮

ISO 5983-2:2009 specifies a method for the determination of nitrogen content of animal feeding stuffs according to the Kjeldahl method, and a method for the calculation of the crude protein content. It is suitable for use as a semi-micro rapid routine method using block digestion, copper catalyst, and steam distillation into boric acid. The method is applicable to the determination of greater than 0,5 % mass fraction Kjeldahl nitrogen in animal feeding stuffs, pet foods, and their raw materials. The method does not measure oxidized forms of nitrogen nor heterocyclic nitrogen compounds. The method does not distinguish between protein nitrogen and non-protein nitrogen.