GB/T 19941.2-2019Leather and fur -- Determination of formaldehyde content -- Part 2: Colorimetric method (English PDF)

Foreword

GB/T 19941 "Leather and fur - Determination of formaldehyde content" consists

of the following 3 parts.

- Part 1.High performance liquid chromatography method;

- Part 2.Colorimetric method;

- Part 3.Formaldehyde emissions.

This Part is Part 2 of GB/T 19941.

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

This Part replaces colorimetric method in GB/T 19941-2005 "Leather and fur-

Chemical tests - Determination of formaldehyde content".

Compared with GB/T 19941-2005, the main technical changes in this Part are

as follows.

- added references of QB/T 1273, QB/T 2717, GB/T 19941.1; deleted

references of QB/T 1266 and QB/T 2707 (see Clause 2 of this Edition,

Clause 2 of Edition 2005);

- modified "3 Principle" (see Clause 3 of this Edition, 5.1 of Edition 2005);

- added "sodium lauryl sulfate" as extraction solution (see 4.2 of this Edition);

- modified expiry date of Nessler's reagent (see 4.3 of this Edition, 5.2.2 of

Edition 2005);

- deleted air conditioning requirements before weighing in the preparation of

samples (see 5.4.2.3 of Edition 2005);

- modified types and specifications of glassware in instruments and

equipment (see Clause 5 of this Edition, 5.3 of Edition 2005);

- modified composition of blank solution in "Inspection of other compounds

that develop color with acetylacetone"; added the processing method when

the absorbance value is higher than 0.05 (see 6.5 of this Edition, 5.4.6 of

Edition 2005);

- added regulations for the direct preparation of formaldehyde standard

solutions from commercially available reference materials (see 6.6 of this

Edition);

- modified calculation formula of formaldehyde content (see 6.7 of this Edition,

1 Scope

This Part of GB/T 19941 specifies the method for determination of free and

hydrolyzed formaldehyde content in leather and fur by colorimetric method.

This Part is applicable to determination of formaldehyde content in various

leathers, furs and their products.

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

Under the specified conditions, use the extraction solution to extract the sample.

Mix the resulting extract with acetylacetone. Through the reaction, a yellow

compound (3,5-diacetyl-1,4-dihydrolutidine) is produced. Determine the

absorbance of the compound at the specified wavelength.

4 Reagents and materials

Unless otherwise specified, all reagents used are analytical reagents, and all

solutions are aqueous solutions.

5 Instruments and equipment

Spectrophotometer. wavelength is 412nm, equipped with suitable cuvette.

It is recommended to use 20mm cuvette; 40mm or 50mm cuvette can also be

used.

6 Test steps

The preparation of leather samples is carried out in accordance with QB/T 2716.

The preparation of fur samples is carried out in accordance with QB/T 1272.

In order to determine the absorbance of the filtrate (6.2) itself, transfer 5mL of

filtrate into a 25mL Erlenmeyer flask (5.2). Add 5mL of ammonium acetate

solution (4.4).

7 Result representation

The free formaldehyde content in the sample is expressed in mg/kg, to the

nearest of 0.1mg/kg.

8 Test report

Annex A

(informative)

Structural changes in this Part compared with ISO 17226-2.2018

Compared with ISO 17226-2.2018, this Part has more structural adjustments.

See Table A.1 for the comparison of specific chapter numbers.

Annex B

(informative)

Technical differences between this Part and ISO 17226-2.2018 and their

reasons

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