Method for measuring nonprotein nitrogen content in liquid

Abstract

The invention provides a method for measuring nonprotein nitrogen content in liquid, which includes the following steps: separating protein nitrogen from liquid so as to obtain a to-be-measured sample containing nonprotein nitrogen; adding potassium persulfate in the to-be-measured sample to obtain a mixed solution under the heating condition; performing ultraviolet catalysis and high-temperature heating to the mixed solution sequentially, so as to obtain a digestion product; detecting the digestion product to obtain ultraviolet spectrum data; and obtaining the nonprotein nitrogen content in the liquid as per the ultraviolet spectrum data and a predetermined standard curve. Through the adoption of the method provided by the invention, the digestion of the nitrogenous ingredient in the liquid sample is more complete, the digestion effect is better, the digestion of the nonprotein nitrogen as well as the digestion of the reductive ingredient in the liquid can be realized, the reductive function of the to-be-measured sample is lost, the interference in the nonprotein nitrogen digestion is reduced, so that the digestion effect becomes more uniform, the recovery rate of the nonprotein nitrogen measurement is improved, and the accuracy of the measurement result is improved.

Description

technical field [0001] The invention relates to the technical field of nitrogen analysis and determination, in particular to a method for determining the content of non-protein nitrogen in liquid. Background technique [0002] Protein is the material basis of life. Due to the complexity of protein composition and properties, the total nitrogen content is usually used to express the protein nitrogen content. However, total nitrogen also contains a large amount of non-protein nitrogen components such as amino acids, ribonucleic acid, alkaloids, nitrates, nitrites, and ammonia salts, which bring large errors to the determination of protein nitrogen. For example, in the determination of liquid nutrients, the method of replacing the protein nitrogen content with the above-mentioned total nitrogen content will cause the obtained protein content to be higher than the actual protein content, which will affect the evaluation of the quality of the liquid nutrients and give criminals a...

AI Technical Summary

Problems solved by technology

[0004] High-pressure digestion has a better digestion effect on inorganic nitrogen in non-protein nitrogen, but for certain nitrogen heterocyclic compounds and plant alkaloids, such as theophylline, due to its complex structure, there are Incomplete and incomplete digestion, resulting in low recovery of non-protein nitrogen determination, resulting in inaccurate test results

For liquid samples, especially liquid nutrients, most of the non-protein nitrogen is plant alkaloids or nitrogen heterocyclic compounds, and the liquid also contains reducing substances, such as sugars, which will react with oxidants, Thus affecting the digestion of nitrogen-containing components, when the non-protein nitrogen content is measured by the above method, the digestion product obtained is not complete and thorough, resulting in inaccurate measurement results

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