Method for measuring nonprotein nitrogen content in liquid

A determination method and non-protein technology, applied in the direction of color/spectral property measurement, etc., can solve the problems of incomplete and thorough digestion products, low recovery rate of non-protein nitrogen, inaccurate determination results, etc. The effect of improving detection efficiency

Inactive Publication Date: 2012-06-27
CHINA TOBACCO GUANGDONG IND
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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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  • Method for measuring nonprotein nitrogen content in liquid
  • Method for measuring nonprotein nitrogen content in liquid
  • Method for measuring nonprotein nitrogen content in liquid

Examples

Experimental program
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Effect test

Embodiment 1

[0067] 11 g of sodium nitrate was dissolved in 100 mL of distilled water to obtain a sodium nitrate stock solution with a mass concentration of 10.0%. Accurately pipette 1.0mL, 2.0mL, 4.0mL, 6.0mL, 8.0mL, 10.0mL of the standard stock solution, and use 0.5% acetic acid solution to dilute it to 100mL respectively to obtain a series of sodium nitrate standards solution to be tested. Take 2 mL of the standard solution to be tested respectively, pour it into the sample tube of the continuous flow analyzer and measure it in parallel three times respectively, and get the average value. In the continuous flow analyzer, the sample injection volume is 0.1mL / min, the injection time is 100s, and the flushing time is 120s. First at 90°C, add 2mL of potassium persulfate solution with a molar concentration of 0.3mol / L in the standard solution to be tested, the injection volume of potassium persulfate solution is 0.8mL / min, then the mixed solution obtained at 90 Under the acidic conditions ...

Embodiment 2

[0073] 3.6032g of theophylline was dissolved in distilled water and adjusted to 100mL to obtain a stock solution of theophylline with a mass concentration of 3.48%. Pipette 5 mL of the theophylline stock solution, and dilute to 100 mL with 0.5% acetic acid solution by volume fraction to obtain the theophylline solution to be tested. Pipette 2.0 mL of the theophylline solution to be tested, pour it into the sample tube of the flow analyzer and perform three parallel measurements, and get the average value. In the continuous flow analyzer, the sample injection volume is 0.1mL / min, the injection time is 100s, and the flushing time is 120s. First at 90 DEG C, in the theophylline solution to be tested, adding 2mL of potassium persulfate solution with a molar concentration of 0.3mol / L, the injection volume of potassium persulfate solution is 0.8mL / min, then the mixed solution obtained in Under the acidic conditions provided by hydrochloric acid at 90°C, UV lamps were irradiated for...

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/33
Inventor 孔浩辉
Owner CHINA TOBACCO GUANGDONG IND
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