GB/T 2441.2-2001 Urea determination method - Determination of biuret content - Spectrophotometric method GB/T2441.2-2001 Standard download decompression password: www.bzxz.net

GB/T 2441.2—2001
This standard is a revision of GB/T2443-1991 "Spectrophotometric method for determination of dihydrogen phosphate content in urea". This standard adopts ISO2754:1973 "Spectrophotometric method for determination of dihydrogen phosphate content in industrial urea" in a non-equivalent manner. The main technical differences between this standard and GB/T2443-1991 and ISO2754:1973 are as follows: The basic standard HG/T2843-1997 for the chemical industry is quoted, and the GB/T601 series standards are no longer quoted. 1
2 The test solution preparation in the analysis steps is simplified.
This standard is the second part of GB/T2441 "Determination method of urea". GB/T2441 also includes the following parts:
Part 1 GB/T2441.1-2001
Part 3
GB/T 2441.3—2001
GB/T2441.4—2001
Part 4
Part 5
Part 6
Part 7
GB/T 2441.5--2001
GB/T 2441.6—-2001
GB/T 2441.7—2001
Part 8
GB/T 2441.8—2001
Part 9
GB/T2441.9—2001
Determination of urea
Determination of total nitrogen content
Determination of water content Karl Fischer method
Determination of urea
Determination of urea
Determination of urea
Determination of urea
Determination of urea
Determination of urea
Determination of urea
This standard shall replace GB/T2443--1991 from the date of its implementation. This standard is proposed by the State Bureau of Petroleum and Chemical Industry. Determination of iron content o-phenanthroline spectrophotometric method Determination of alkalinity Volumetric method
Determination of water-insoluble matter content
Gravimetric method
Determination of particle size Sieving method
Determination of sulfate content Visual turbidimetry
Determination of methylene disulfide content Spectrophotometric method This standard is under the jurisdiction of the National Technical Committee for Standardization of Fertilizers and Soil Conditioners and is responsible for its interpretation. Drafting units of this standard: National Fertilizer Quality Supervision and Inspection Center (Shanghai), PetroChina Urumqi Petrochemical Company Fertilizer Plant, Sinopec Jiujiang Branch, Hainan Fudao Chemical Co., Ltd. Main drafters of this standard: Zhang Qiuzhen, Sha Yanping, Jiang Jianxin, Yang Jiqun, Guo Zutan. This standard was first issued in 1981.
GB/T 2441.2—2001
ISO Foreword
ISO (International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The formulation of international standards is usually carried out through ISO technical committees. Each member body interested in the project of an established technical committee has the opportunity to join the technical committee, and governmental or non-governmental international organizations associated with ISO can also participate in this work. The draft international standard adopted by the technical committee must be sent to the member bodies for approval before being approved as an international standard by the ISO Council.
ISO2754 international standard was drafted by ISO/TC47 Chemical Technical Committee and sent to member units in June 1972. This standard has been approved by member organizations of the following countries:Austria
Belgium
Hungary
Ireland
Italy
New Zealand
Portugal
Romania
Turkey
The International Union of Pure and Applied Chemistry (IUPCA) has also approved this standard. The following member countries disagree with this standard for technical reasons. Netherlands
1 Scope
National Standard of the People's Republic of China
Determination of urea
Determination of biuret contentSpectrophotometric method
This standard specifies the determination of biuret content in urea by the copper complex salt spectrophotometric method. GB/T 2441. 2—2001
neq ISO 2754:1973
Replaces GB/T2443—1991
This standard applies to the determination of the content of urea biuret for industrial and agricultural use synthesized from ammonia and carbon dioxide. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. HG/T2843-1997 Commonly used standard titration solutions, standard solutions, reagent solutions and indicator solutions in chemical analysis of fertilizer products 3 Principle
Biuret forms a purple-red complex in an alkaline solution of copper sulfate and potassium sodium tartrate, and its absorbance is measured at a wavelength of 550 nm.
4 Reagents and solutions
Unless otherwise specified, the reagents, solutions and water used in this test method shall comply with the requirements of HG/T 2843. 4.1 Copper sulfate solution, 15 g/L
4.2 Potassium sodium tartrate alkaline solution, 50 g/L; 4.3 Dipivoxel standard solution, 2.00 g/L. 5 Instruments
General laboratory instruments and
5.1 Water bath, 30℃±5℃;
5.2 Spectrophotometer with 3 cm absorption cell. 6 Analysis steps
6.1 Drawing of standard curve
6.1.1 Preparation of standard colorimetric solution
As shown in Table 1, inject the dipivoxel standard solution into eight 100 mL volumetric flasks in turn. Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on July 26, 2001 and implemented on January 1, 2002
Volume of standard biuret bath solution, mL
GB/T 2441.2—2001
Table 1 Amount of biuret standard solution added
Corresponding amount of biuret, mg
Each volumetric bottle is diluted with water to about 50 mL, and then 20.0 mL of potassium sodium tartrate alkaline solution and 20.0 mL of copper sulfate solution are added in sequence, shake well, dilute to the scale, and immerse the volumetric bottle in a water bath at 30℃±5℃ for about 20 minutes, shaking from time to time. 6.1.2 Absorbance determination
Within 30 minutes, use the solution with zero biuret as the reference solution, and use a spectrophotometer to measure the absorbance of the standard colorimetric solution at a wavelength of 550nm. www.bzxz.net
6.1.2 Drawing of standard curve
Use the mass (mg) of diaminobenzene contained in 100mL standard colorimetric solution as the horizontal axis and the corresponding absorbance as the vertical axis to draw a graph, or find the linear regression equation.
6.2 Determination
6.2.1 Preparation of test solution
According to the different contents of diaminobenzene in urea, determine the sample weight according to Table 2 and weigh the sample accurately to 0.002 g. Then carefully transfer the weighed sample to a 100mL volumetric flask, add a small amount of water to dissolve (the amount of water added should not exceed 50mL), place it at room temperature, add 20.0mL potassium sodium tartrate alkaline solution and 20.0mL copper sulfate solution in turn, shake well, dilute to the scale, and immerse the volumetric flask in a water bath at 30℃±5℃ for about 20 minutes, shaking from time to time.
Table 2 Weighing sample amount Biuret (X), %
Weighing sample amount, g
6.2.2 Blank test
0.3
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