From the Kjeldahl nitrogen analyzer to the semi-automatic Kjeldahl nitrogen analyzer, and then to the fully automatic nitrogen analyzer, although each step is a small technological advancement, for the operator, it does solve many real operational problems. At present, the automatic nitrogen analyzer is very popular in the industry due to its high sensitivity, fast analysis speed, and high degree of automation. However, in essence, the automatic nitrogen analyzer is also based on the Kjeldahl method, so it is fully automatic The scope of application of the nitrogen analyzer is actually the scope of application of the Kjeldahl nitrogen analyzer. The measurement principle of the Kjeldahl nitrogen analyzer can be simply understood as calculating the protein content by measuring the nitrogen content, and the conversion is based on the ratio of the protein content in the food to the nitrogen content in the food, such as the ratio of protein to nitrogen content in milk It is 6.38, the ratio of protein to nitrogen in soybeans is 5.71, and the ratio of protein to nitrogen in ordinary foods is 6.25. The specific measurement experiment is that the sample is digested by high-temperature concentrated sulfuric acid to convert the organic nitrogen in the sample into inorganic ammonium. After the digestion solution is cooled, excess alkali is added to convert the inorganic ammonium into volatile ammonia. After the ammonia is distilled off, it is titrated with a hydrochloric acid standard solution, and finally the nitrogen content in the sample is calculated based on the volume of the consumed hydrochloric acid standard solution. Since the Kjeldahl method based on the automatic nitrogen analyzer is digested by sulfuric acid at high temperature, it can only convert organic nitrogen into inorganic ammonium, but not nitrate nitrogen (such as nitrate and nitrite). Therefore, the Kjeldahl method is suitable for food, agricultural products, cosmetics, medicine, etc. that do not contain nitrate nitrogen. In other words, the scope of application of the automatic nitrogen analyzer is food, agricultural products, cosmetics, medicine, etc. that do not contain nitrate nitrogen. Gost Dn500 Pn6 Flange,Gost Plate Flange,Gost 12821 Steel Flange,Gost Carbon Steel Pipe Flange New Century Machinery Co., Ltd , https://www.ncmflange.com
