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GB/T 28019-2011Adornment - Determination of Chromium (VI) - 1, 5-Diphenylcarbohydrazide spectrophotometric method (English PDF)

饰品六价铬的测定二苯碳酰二肼分光光度法

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

October 31, 2011

Implementation date

February 1, 2012

Scope

GB/T 28019-2011 is the English-translated version of 饰品六价铬的测定二苯碳酰二肼分光光度法.

GB/T 28019-2011 is the Chinese standard "Adornment - Determination of Chromium (VI). 1, 5-Diphenylcarbohydrazide spectrophotometric method". Its scope clause reads: This standard specifies the 1,5-Diphenylcarbohydrazide spectrophotometric method for Chromium (VI).

This Standard applies to the determination of Chromium (VI) in adornment. Its clauses include method and principle; reagents and materials; apparatus; analysis steps; representation of the result; test report.

It was issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Sta on OCTOBER 31, 2011 and took effect on FEBRUARY 1, 2012.

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Document preview — GB/T 28019-2011

National Standard of the People's Republic of China

ICS: 39.060
Classification: Y 88

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

Foreword3
1 Scope4
2 Method and Principle4
3 Reagents and Materials4
4 Apparatus5
5 Analysis Steps6
6 Representation of the Result7
7 Test Report8

Foreword

This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.

1 Scope

This standard specifies the 1,5-Diphenylcarbohydrazide spectrophotometric method for Chromium (VI).

This Standard applies to the determination of Chromium (VI) in adornment.

2 Method and Principle

Use alkaline leaching solution to leach the water-soluble and water-insoluble hexavalent chromium compounds from the sample. In acidic solution, the hexavalent chromium from the leachate reacts with the diphenylcarbazide and the reaction forms the purple-red complex. At the wavelength of 540 nm, perform spectrophotometric determination.

3 Reagents and Materials

Unless otherwise stated, in analysis, it can only use the reagents, which are confirmed as the analytic reagents and distilled water, or deionized water, or the water with the equal purity.

3.1 Nitric acid - guarantee reagent.

3.2 Sulfuric acid - guarantee reagent.

3.3 Sodium hydroxide.

3.9 Acetone.

3.10 Sulfuric acid solution (1+9).

3.11 Nitric acid solution - c (HNO3) = 5mol/L. Weigh and take 31mL of nitric acid (3.1); add it into 69mL of water. Nitric acid with brown smoke shall not be used for preparation.

3.15 Standard solution of hexavalent chromium - c [Cr (VI)] = 5.0mg/L. Pipette 5.0mL of standard stock solution of hexavalent chromium (3.14) in a 100 mL volumetric flask; dilute it to the mark with water; shake it evenly. Prepare it when it is used.

3.16 Diphenylcarbazide (DPC) solution. Weigh and take 0.5g of diphenylcarbazide (3.8); dissolve it in 100 mL of acetone (3.9); store it in a brown bottle. When solution's color fades, it should be reconstituted.

4 Apparatus

Common laboratory apparatus and the following items.

4.1 Spectrophotometer - wavelength 420nm~700nm.

4.2 Oscillating water bath kettle. […]

5 Analysis Steps

5.1 Sample Preparation

5.1.1 Metal Material

Process the sample into the crumb or strip whose diameter are no more than 1 mm and whose length are no more than 5 mm.

5.3 Color Rendering

Add 2.0mL of diphenylcarbazide (DPC) solution (3.16) into the filtrate (5.2); mix it evenly; add sulfuric acid solution (3.10); make filtrate's pH reach 2±0.5; then transfer the whole filtrate into a 100mL volumetric flask; use water to dilute it until the mark; shake it evenly; place it for 0.5h.

5.4 Calibration Solution

Respectively pipette 0.0mL, 2.0mL, 4.0mL, 6.0mL, 8.0mL and 10.0mL of standard solution of hexavalent chromium (3.15) into the 100mL volumetric flask; add 50mL of water; add 2.0mL of diphenylcarbazide (DPC) solution (3.16); mix it evenly; add 2 drops of sulfuric acid solution (3.10); make filtrate's pH reach 2±0.5; use water to dilute it until the mark; shake it evenly; place it for 0.5h.

5.5 Determination

Adopt 1 cm absorption pool; at the place whose absorption wavelength is 540 nm, use ultraviolet-visible spectrophotometer (4.1) to measure the absorbance value of the calibration solution; draw the calibration curve by corresponding the absorbance value with the concentration value.

6 Representation of the Result

In the sample, the content of hexavalent chromium shall be counted in mass fraction - w. The numerical value shall be expressed in milligrams per kilogram (mg/kg) and shall be calculated according to formula (1).

7 Test Report

Test report shall at least include the following information. […]

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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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