Method for detecting nitrogen content

A detection method and technology for nitrogen content, applied in the field of analytical chemistry, can solve the problems of high cost and cumbersome steps, and achieve the effects of high accuracy, avoiding foam accumulation, and obvious changes in the titration end point.

Active Publication Date: 2016-05-11
GUIZHOU RES INST OF CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Aiming at the problems of cumbersome steps and high cost in the existing determination methods, the purpose of the present invention is to provide an economical, reasonable, simple and feasible detection method

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The compound fertilizer was dried at 80°C to constant weight, and its moisture content was measured. Accurately weigh 0.3g of compound fertilizer with a precision electronic balance (the balance is accurate to 0.0001g) and place it in a flask, add 9mL of sulfuric acid with a concentration of 95% by mass, digest at 200°C for 4min, increase the temperature to 340°C and continue digestion for 15min, Lower the temperature to 80°C and heat for 4 minutes, cool to room temperature, add 27mL distilled water, 3 drops of phenolphthalein, and use 0.3mol / L sodium hydroxide to titrate the remaining sulfuric acid in the solution. Add 2 times the volume of dipropylene glycol in dimethyl sulfoxide, use phenolphthalein as an indicator, and use 0.6 mol / L sodium hydroxide solution to titrate ammonium ions, record the titration volume, and calculate the nitrogen content.

Embodiment 2

[0023] The compound fertilizer was dried at 90°C to constant weight, and its moisture content was measured. Weigh another 0.4g of compound fertilizer with a precision electronic balance (the balance is accurate to 0.0001g) and place it in a flask, add 16mL of sulfuric acid with a concentration of 96% by mass, digest at 210°C for 3min, raise the temperature to 345°C and continue digestion for 13min, Lower the temperature to 90°C and heat for 3 minutes, cool to room temperature, add 36mL distilled water, 3 drops of phenolphthalein, and use 0.5mol / L sodium hydroxide to titrate the remaining sulfuric acid in the solution. After the titration, add 1.5 times the solution volume of dipropylene glycol, Add dimethyl sulfoxide three times the volume of dipropylene glycol, use phenolphthalein as an indicator, and use 0.7mol / L sodium hydroxide solution to titrate ammonium ions, record the titration volume, and calculate the nitrogen content.

Embodiment 3

[0025] The compound fertilizer was dried at 100°C to constant weight, and its moisture content was measured. Accurately weigh 0.5 g of compound fertilizer with a precision electronic balance (the balance is accurate to 0.0001 g) and place it in a flask, add 25 mL of sulfuric acid with a mass percent concentration of 98%, digest at 220°C for 2min, increase the temperature to 350°C and continue digestion for 12min, and Lower the temperature to 80°C and heat for 4 minutes, cool to room temperature, add 50mL distilled water, 3 drops of phenolphthalein, and use 0.6mol / L sodium hydroxide to titrate the remaining sulfuric acid in the solution. After the titration, add dipropylene glycol twice the volume of the solution, add Dimethyl sulfoxide with 4 times the volume of dipropylene glycol, using phenolphthalein as an indicator, titrate ammonium ions with 0.8 mol / L sodium hydroxide solution, record the titration volume, and calculate the nitrogen content.

[0026] Total nitrogen conten...

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Abstract

The invention relates to a method for detecting the element content of a material and in particular relates to a method for detecting the nitrogen content of a compound fertilizer, belonging to the field of analytical chemistry. The method for detecting the nitrogen content comprises the following steps: drying the compound fertilizer till constant weight, drying the compound fertilizer till constant weight again after grinding and sieving the compound fertilizer, weighing required amount of compound fertilizer and digesting the compound fertilizer with sulfuric acid, neutralizing the remaining sulfuric acid with sodium hydroxide after digestion is completed, adding dipropylene glycol and dimethyl sulfoxide, using phenolphthalein as an indicator and titrating ammonium ions by utilizing a sodium hydroxide solution. The method has the beneficial effects that the method is simple and feasible and has the advantages that the three steps including alkalization distillation, boron absorption and acidometric titration are omitted compared with a kjeldahl method; besides, the required equipment and instruments, chemicals and reagents are articles commonly used in laboratories, so that the method has obvious economic benefits.

Description

technical field [0001] The invention relates to a method for detecting the content of material elements, in particular to a method for detecting the content of nitrogen in compound fertilizers, and belongs to the field of analytical chemistry. Background technique [0002] In the process of production practice, the nitrogen content of fertilizer is a very important factor. Traditional determination methods include the Kjeldahl method, which requires a special Kjeldahl instrument, and the steps are cumbersome and time-consuming. High-performance liquid chromatography or gas chromatography is often used in the modern determination of nitrogen content. Although the detection speed is fast, the equipment and maintenance costs are expensive, and it is difficult to be widely used in ordinary laboratories and production units. In addition, it also has high requirements for standard products, and the choice of mobile phase and chromatographic column has a great influence on the det...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/78
CPCG01N21/78
Inventor 田娟杨杰马福波周昌平陈文兴王瑶陈思帆
Owner GUIZHOU RES INST OF CHEM IND
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