GB/T 25222-2010Inspection of grain and oils - Determination of phosphide residues in grain-spectrophotometric method (English PDF)
粮油检验 粮食中磷化物残留量的测定 分光光度法
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
September 26, 2010
Implementation date
March 1, 2011
Scope
GB/T 25222-2010 is the English-translated version of 粮油检验 粮食中磷化物残留量的测定 分光光度法.
GB/T 25222-2010 lays down a spectrophotometric procedure for measuring phosphide residues in grain, covering the terms and definitions, the measuring principle, the reagents and materials, the instruments and equipment, sampling, sample preparation, the test steps, and the calculation and expression of results.
Clause 1 states that the standard applies to the determination of phosphide fumigant residues in grain and fixes the detection limit of the method at 0.01 mg/kg.
The definitions in clause 3 treat a phosphide as a phosphorus-bearing compound used as a fumigant, such as aluminium phosphide, and express the residue as the mass fraction of phosphine in the sample.
The principle in clause 4 is that acid and water release phosphine from the sample, the gas is driven off and absorbed in acidic potassium permanganate solution where it is oxidised to phosphoric acid, the acid forms ammonium phosphomolybdate with ammonium molybdate, stannous chloride reduces this to molybdenum blue, and the absorbance is read against a standard curve.
Clause 5 sets out the reagents, among them two strengths of potassium permanganate solution, two dilutions of sulfuric acid, saturated sodium sulfite solution and ammonium molybdate solution, and requires analytical grade reagents and water meeting grade three of GB/T 6682.
Among the normative references is GB 5491 on sampling of grain and oilseeds. The standard was proposed by the national food authority and drafted by Nanjing University of Finance and Economics, with grain and oil quality supervision and inspection stations in Jiangsu, Nanjing and Jilin taking part. It was issued on 26 September 2010 and has applied since 1 March 2011.
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Document preview — GB/T 25222-2010
National Standard of the People's Republic of China
- ICS
- 67.060
- Classification
- B 20
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Terms and Definitions
- 4 Principle
- 5 Reagents and materials
Foreword
The standard proposed by the National Food Authority.
1 Scope
This standard specifies the spectrophotometric determination of residues in food in phosphide terms and definitions, principles, reagents and materials, instruments and Equipment for sampling, sample preparation, the steps, the results of the calculation and presentation.
This standard applies to the determination of phosphide fumigant residues in food. The detection limit of the standard method of 0.01mg/kg.
2 Normative references
The following documents contain provisions which, through reference in this standard and become the standard terms. For dated references, subsequent Amendments (not including errata content) or revisions do not apply to this standard, however, encourage the parties to the agreement are based on research Whether the latest versions of these documents. For undated reference documents, the latest versions apply to this standard.
GB 5491 grain and oilseeds testing for sampling, and sample method Laboratory use specifications and test methods
GB/T 6682 Analysis
3 Terms and Definitions
The following terms and definitions apply to this standard.
3.1 Phosphide
Phosphorus-containing compound used as a fumigant, such as aluminum phosphide and the like.
3.2 Phosphide residues
Under this standard are measured residual phosphide content in grain. Phosphine accounting sample mass fraction representation.
4 Principle
Phosphide samples under the action of acid and water to produce phosphine gas, evaporated and taken up in the acidic potassium permanganate solution is oxidized to phosphorus Acid, and then generate and ammonium molybdate ammonium phosphomolybdate effect, reduced to a blue molybdenum compound with stannous chloride --- blue, absorbance was measured using a standard curve Statutory amount.
5 Reagents and materials
Unless otherwise specified, the reagents used were of analytical grade. Test water should comply with GB/T 6682 in the three requirements.
5.1 Potassium permanganate solution
(16.5g/L). Weigh 16.5g of potassium permanganate, after dissolved in water and diluted to 1000mL, stand three or heating Boil 3min, cooled and allowed to stand overnight, filtered alternate with glass wool or asbestos.
5.2 Potassium permanganate solution (3.3g/L)
Take a certain amount of potassium permanganate solution (5.1) was diluted with water five times.
5.3 Sulfate (117)
Take 28mL 98% sulfuric acid was slowly added 400mL of water, 500mL water was added to the cooled.
5.4 Sulfate (15)
Take 83.3mL 98% sulfuric acid was slowly added 400mL of water, cooled water was added to 500mL.
5.5 Saturated sodium sulfite solution
Take 28.5g of anhydrous sodium sulfite, add about 70mL of water, micro-heat to dissolve, cooled and diluted to 100mL.
5.6 Ammonium molybdate solution
50g/L. […]
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 15 pages — is available in the English PDF.
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Related Standards
GB 5491-1985 — Inspection of grain and oilseeds-Methods for samplingand sample reduction
GB/T 6682-2008 — Water for analytical laboratory use - Specification and test methods
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