GB/T 22807-2019Leather and fur - Chemical tests - Determination of chromium VI content (English PDF)

Foreword

This Standard was drafted according to the rules given in GB/T 1.1-2009.

This Standard replaces GB/T 22807-2008 "Leather and fur - Chemical tests -

Determination of chromium VI content".

Compared with GB/T 22807-2008, the main technical changes of this Standard

are as follows.

- ADD references to GB/T 6682 and GB/T 38402 (see Clause 2 of this

Standard, Clause 2 of 2008 edition);

- DELETE the specific test conditions involved in the principle, and ADJUST

some of the contents to "7.1 Preparation of analytical solution" (see Clause

3 and 7.1 of this Standard, Clause 3 of 2008 edition);

- ADD methanol in "Reagents and materials" (see 4.9 of this Standard);

- MODIFY the requirements for the frequency of oscillator (see 5.1 of this

Standard, 5.1 of 2008 edition);

- ADD filter paper and analytical balance in "Apparatus and equipment" (see

1 Scope

This Standard specifies the colorimetric method for the determination of

chromium content in leather and fur.

2 Normative references

The following referenced documents are indispensable for the application of

this document. 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)

3 Principle

Use phosphate buffer to extract the soluble chromium in the sample. If

necessary, it may use solid phase extraction to remove the co-extracted colored

substances that interfere with the test. After filtration, the chromium in the filtrate

is reacted with 1,5-diphenylcarbazide under acidic conditions to form a purple-

red complex.

4 Reagents and materials

Unless otherwise stated, all reagents used are of analytical grade.

5 Apparatus and equipment

Quartz cuvette, thickness of 2 cm, or other cuvettes of suitable thickness.

Solid phase extraction column, C18 or PA, or packing with equivalent effect.

Analytical balance, to the nearest 0.1 mg.

6 Sampling and preparation of samples

Leather. according to the provisions of QB/T 2716.

Fur. according to the provisions of QB/T 1272.

REMOVE the glue and attachments on the sample as cleanly as possible, MIX

the sample evenly, and PUT it into a clean sample bag for test.

7 Test procedure

PIPETTE 10 mL of the analytical solution obtained in 7.1, ADD an appropriate

amount of chromium standard solution, so that the content of chromium is close

to 2 times (+/-25 %) of the content of chromium in the original analytical solution

(7.1). The final volume of the solution after adding the chromium standard

solution does not exceed 11 mL.

8 Calculation and expression of results

Calculate the recovery rate according to formula (4).

For the chromium content in the sample, it takes the arithmetic mean value of

the two parallel test results as the test result, expressed in mg/kg, to the nearest

9 Test report

The test report shall include the following.

Annex A

(informative)

Structural changes of this Standard compared with ISO 17075-1.2017

Compared with ISO 17075-1.2017, this Standard has many adjustments in

structure. See Table A.1 for the comparison of specific clause numbers.

......