GB/T 38402-2019 in English

《GB/T 38402-2019皮革和毛皮 化学试验 六价铬含量的测定：色谱法》由TC252（全国皮革工业标准化技术委员会）归口，主管部门为中国轻工业联合会。

ChinaStandards.net is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.

This standard is developed in accordance with the rules given in GB/T 1.1-2009.

This standard has been redrafted and modified in relation to ISO 17075-2:2017 Leather - Chemical determination of chromium(VI) content in leather - Part 2: Chromatographic method.

This standard is changed largely from ISO 17075-2:2017 in terms of structure; the comparison between this standard and ISO 17075-2:2017 in clause/subclause number is listed in Annex A.

Technical differences have been made in this standard with respect to ISO 17075-2:2017, and relevant technical differences and their causes have been listed in Annex B.

The following editorial changes have also been made in this standard:

——The standard name is revised to Leather and fur - Chemical tests - Determination of chromium(VI) content: Chromatographic method;

——The model and specification of columns in Annexes B and C to ISO 17075-2:2017 are modified, and the instrument parameters are adjusted accordingly;

——The validation data in Annex A to ISO 17075-2:2017 is changed to the validation results from domestic laboratories;

——The test data in Annex D to ISO 17075-2:2017 is changed to the test data from domestic laboratories.

This standard was proposed by China National Light Industry Council.

This Standard is under the jurisdiction of the National Technical Committee 252 on Leather of Standardization Administration of China (SAC/TC 252).



Leather and fur - Chemical tests - Determination of chromium(VI) content: Chromatographic method

1 Scope

This standard specifies a chromatographic method for the determination of chromium(VI) content in leather and fur.

This standard is applicable to the determination of the chromium(VI) content in various leathers, furs and their products.

2 Normative references

The following documents are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T 6682-2008, ISO 3696:1987, MOD)
GB/T 22807 Leather and fur - Chemical tests - Determination of chromium (VI) content: Colorimetric method (GB/T 22807-2019, ISO 17075-1:2017, MOD)
QB/T 1267 Fur - Chemical, physical and mechanical and fastness tests - Sampling location (QB/T 1267-2012, ISO 2418: 2002, MOD)
QB/T 1272 Fur - Preparation of chemical test samples (QB/T 1272-2012, ISO 4044: 2008, MOD)
QB/T 1273 Fur - Chemical tests - Determination of volatile matter (QB/T 1273-2012, ISO 4684:2005, MOD)
QB/T 2706 Leather - Chemical, physical and mechanical and fastness tests - Sampling location (QB/T 2706-2005, ISO 2418: 2002, MOD)
QB/T 2716 Leather - Preparation of chemical test samples (QB/T 2716-2018, ISO 4044: 2008, MOD)
QB/T 2717 Leather - Chemical tests - Determination of volatile matter (QB/T 2717-2018, ISO 4684: 2005, MOD)

3 Principle

Extractable chromium(VI) is leached from the specimen in phosphate buffer solution. An aliquot of the filtered extract is analysed for Cr(VI) using ion-exchange chromatography with UV-VIS or DAD detector.

4 Reagents and materials

Unless otherwise specified, analytical grade chemicals shall be used.

4.1 Water: The test water shall be Grade 3 in accordance with GB/T 6682.

4.2 Phosphate buffer solution (0.1 mol/L): Dissolve 22.8 g of dipotassium hydrogenphosphate (K2HPO4·3H2O, with the relative molecular mass of 228) in 1,000 mL distilled water, adjusted to pH 8.0 ± 0.1 with phosphoric acid (4.3). Degas this solution with either argon or nitrogen (4.7) or ultrasonic bath.

Note: Phosphate buffer is recommended to be freshly prepared. However, the solution may be kept for up to one week in a refrigerator at 0℃ to 4℃ but shall be warmed to room temperature and degassed prior to use.

4.3 Phosphoric acid (H3PO4) solution: Dilute 700 mL phosphoric acid (with a mass fraction of 85% and a density of 1.71 g/mL) to 1,000 mL with distilled water.

Note: First add 200 mL of distilled water into a 1,000 mL volumetric flask, and then add 700 mL of phosphoric acid and dilute to the mark with distilled water.

4.4 Potassium dichromate (K2Cr2O7) standard: dried for (16 ± 2) h at (102 ± 2)℃.

4.5 Chromium(VI) standard stock solution (1 mg/mL): Weigh 2.829 g of potassium dichromate (4.4), dissolve with distilled water, and then transfer, rinse, and dilute it to the mark into a 1,000 mL volumetric flask. One millilitre of this solution contains 1 mg of chromium.

4.6 Chromium(VI) standard solution (1 μg/mL): Pipette 1 mL of chromium(VI) standard stock solution (4.5) into a 1,000 mL volumetric flask and make up to the mark with phosphate buffer solution (4.2). One millilitre of this solution contains 1 μg of chromium.

Note 1: The solution can be kept for up to one week in a refrigerator at 0 ℃ to 4 ℃ but shall be warmed to room temperature prior to use.

Note 2: The 1 μg/mL stock solution of chromium(VI) at this concentration level is an alternative available commercially. The standard samples of chromium (VI) on the market include "Standard Solution of Cr (VI)".

4.7 Argon (or nitrogen, argon is recommended): oxygen-free, purity ≥ 99.99%.

Note: The relative density of argon is higher than that of air, and it is not easy to escape upward when opened.

Foreword i
1 Scope
2 Normative references
3 Principle
4 Reagents and materials
5 Apparatus
6 Sampling and preparation of specimens
7 Test procedures
8 Calculation and expression of results
9 Test report
Annex A (Informative) Structural changes of this standard with respect to ISO 17075-2:
Annex B (Informative) Technical differences between this standard and ISO 17075-2:2017 and their causes
Annex C (Informative) Chromatographic conditions for direct detection method
Annex D (Informative) Chromatographic conditions for method with post-column reaction
Annex E (Informative) Precision
Annex F (Informative) Comparison between the colorimetric method (GB/T 22807) and the ionic chromatography method (GB/T 38402)