尿素、氯化铵、碳酸铵对牛奶样品微量凯氏定氮法的干扰

With an aim of exploring the impact of urea, ammonium chloride and ammonium carbonate in the Micro-Kjeldahl Determination on content of protein in milk samples. The Kjeldahl nitrogen determination are exploited to detect the content of protein in milk samples contained no urea, ammonium chloride and ammonium carbonate. Then the protein content in the milk samples which are added by defined urea, ammonium chloride and ammonium carbonate are check by the same method. Compared to the milk sample with nitrogen-contained substance, the results of the milk sample without additive have a higher repeatability and accuracy. Both of the relative errors of the detection results of the two samples exceed 5% almost. The non-protein nitrogen substance such as Urea, ammonium chloride, ammonium carbonate and could interfere with the detection results of Micro-Kjeldahl, and the strength of the interference is coincidence with the contents of the nitrogen in the non-protein substances.