GB/T 2441.9-2010Determination of urea - Part 9: Methylenediurea content - Spectrophotometric method (English PDF)
尿素的测定方法 第9部分：亚甲基二脲含量 分光光度法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
June 30, 2010
Implementation date
January 1, 2011
Scope
GB/T 2441.9-2010 is the English-translated version of 尿素的测定方法 第9部分：亚甲基二脲含量 分光光度法.
GB/T 2441.9-2010 is Part 9 of GB/T 2441 and specifies the determination of the methylenediurea content of urea with the naphthalene dicarboxylic acid disodium salt, or chromotropic acid, method.
Clause 1 restricts the part to the determination of methylenediurea content in urea that contains only a small amount of it. Clause 2 cites a single document, HG/T 2843, to which clause 4 also refers for any reagent, solution or water whose specification and preparation method the part does not give.
The principle in clause 3 is that, under the action of concentrated sulfuric acid, the methylenediurea in the urea decomposes into formaldehyde and urea, and that the formaldehyde reacts with the chromotropic acid reagent to form a purple complex whose absorbance is measured with a spectrophotometer at an absorption wavelength of 570 nm.
Clause 4 opens with a caution that some of the reagents and solutions are corrosive, that splashes on the skin should be washed off at once with water or dealt with in a suitable way and that severe cases need immediate treatment, then gives sulfuric acid, a chromotropic acid solution at 10 g/L made from 1 g dissolved in 100 mL of water and kept in a brown bottle with ten days of stability, and a formaldehyde standard solution whose formaldehyde content is first determined by titrating with a sulfuric acid standard titration solution against 50 mL of a sodium sulfite solution of 126 g/L and three drops of a 1 g/L indicator solution whose name the draft garbles, the formaldehyde mass fraction then following from formula 1 with the molar mass of formaldehyde taken as 0.03003 g/mmol.
The draft breaks off inside that determination, so the clauses after 4.3.1 are not shown.
The foreword states that GB/T 2441 is divided into nine parts, that this part was proposed by the China Petroleum and Chemical Industry Association and is centralized by the national standardization technical committee of fertilizers and soil conditioners (SAC/TC105), and that the part was first released in 2001.
It replaces GB/T 2441.9-2001, was issued on 2010-06-30 and has applied since 2011-01-01.
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Document preview — GB/T 2441.9-2010
National Standard of the People's Republic of China
- ICS
- 65.080
- Classification
- G 20
- Replacing
- GB/T 2441.9-2001
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Principle
- 4 Reagents and solutions
Foreword
GB/T 2441 "Determination of urea" is divided into nine sections.
--- Part 1. total nitrogen content;
--- Part 2. biuret content spectrophotometry;
--- Part 3. Moisture Karl Fischer method;
--- Part 4. iron content - Phenanthroline spectrophotometric method;
--- Part 5. alkalinity volumetric method;
--- Part 6. Water-insoluble content - Gravimetric method;
--- Part 7. particle size sieving;
--- Part 8. sulphate content Visible turbidimetric method;
--- Part 9. methylene diurea content spectrophotometry.
This is Part 9 GB/T 2441's.
This Part replaces GB/T 2441.9-2001 "Determination of urea Determination of methylene diurea content spectrophotometry."
This part is proposed by the China Petroleum and Chemical Industry Association.
This part of the National Standardization Technical Committee and soil conditioners Fertilizers (SAC/TC105) centralized.
This section was first released in 2001.
1 Scope
This section GB/T 2441 with the provisions of the naphthalene dicarboxylic acid disodium salt (chromotropic acid) Determination of urea content of methylene diurea law.
This section applies only to a small amount of urea Determination of methylene diurea containing content.
2 Normative references
The following documents contain provisions which, through reference to GB/T 2441 to the present, constitute provisions of this section. For dated reference documents Member, all subsequent amendments (not including errata content) or revisions do not apply to this section, however, encouraged to reach under this section Parties to research agreement to use the latest versions of these documents. For undated reference documents, the latest versions apply to this section.
HG/T 2843 fertilizer products for chemical analysis commonly used standard titration solution, standard solution, reagent solution and indicator solution
3 Principle
The role of concentrated sulfuric acid, urea methylene diurea decomposition of formaldehyde and urea formaldehyde with naphthalene generate acid disodium salt (chromotropic acid) Reacts purple complex, the absorption wavelength at 570nm, absorbance was measured with a spectrophotometer.
4 Reagents and solutions
The following part-corrosive reagents and solutions, the operator should be careful as splashed on the skin should immediately wash with water or suitable Way to deal with severe cases should be treated immediately.
As used in this section reagent solution and water, in the specifications and method of preparation is not specified, it shall comply with the provisions of HG/T 2843's.
4.1 Sulfuric acid.
4.2 Naphthalene dicarboxylic acid disodium salt (chromotropic acid) solution (10g/L)
1g dissolved naphthalene dicarboxylic acid disodium salt (chromotropic acid) in 100mL of water (solution is stored in a brown bottle, 10 days stability).
4.3 Formaldehyde standard solution
4.3.1 Determination of formaldehyde content. Measure 50mL sodium sulfite solution (126g/L), placed in 250mL conical flask, add 3 drops of thymol Phthalate indicator solution (1g/L), with sulfuric acid standard titration solution [c (12H2SO4 ) = 1mol/L] titrated to colorless. Weigh 3mL formaldehyde solution (called Associate to 0.0002g), placed in the above solution, shake, sulfuric acid standard titration solution [c (12H2SO4 ) = 1mol/L] to the solution of titration Blue to colorless.
Formaldehyde (HCHO) content w1, the mass fraction (%) expressed by the formula (1).
w1 = c x V x 0.03003 x 100m1 (1)
Where.
C --- accurate titration standard solution of sulfuric acid concentration of value in units of moles per liter (mol/L);
Numerical V --- consumption of sulfuric acid standard titration solution volume in milliliters (mL);
Numerical mass m1 --- formaldehyde solution, in grams (g);
--- Formaldehyde 0.03003 mmol mass in grams per millimole of (g/mmol).
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
Referenced standards
Similar standards
Editions of GB/T 2441.9
| Edition | Title | Revision | Status |
|---|---|---|---|
| GB/T 2441.9-2010 | Determination of urea - Part 9: Methylenediurea content - Spectrophotometric method | current edition | Current |
| GB/T 2441.9-2001 | Determination of urea - Part 9: Methylenediurea content - Spectrophotometric method | previous edition | Superseded |
This page sells the current edition, GB/T 2441.9-2010. Earlier editions are listed for reference only.
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Related Standards
HG/T 2843-1997 — Chemical fertilizer products. Standard volumetric, standard, reagent and indicator solutions for chemical analysis
GB/T 2441.1-2008 — Determination of urea - Part 1: Total nitrogen content
GB/T 2441.2-2010 — Determination of urea - Part 2: Biuret content - Spectrophotometric method
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GB/T 2441.9-2010
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