Superseding
Chinese Name	Ƥ���ëƤ ��ѧ���� ��ȩ�����IJⶨ
English Name
Chinese Standard Classification
Professional Classification
ICS Classification
Issued on	2005-09-26
Implemented on	2006-04-01
Abolished on
Issued by	AQSIQ, SAC
Chinese Pages
Word Count	5000 words

1  Scope

This standard specifies the method for the determination of free and hydrolyzed formaldehyde content in leather and fur products.
This standard is applicable to various of leather and fur as well as their products.

2  Normative Reference

The following normative documents contain provisions which, through reference in this standard, constitute provisions of this standard. For dated reference, subsequent amendments (excluding amending error in the text) to, or revisions of, any of these publications do not be applied. However, the parties whose enter into agreement according to these specifications are encouraged to research whether the latest editions of these references are applied or not. For undated references, the latest editions of the normative documents apply.
GB/T 6682-1992  Water for Laboratory Use; Specifications (neq ISO 3696: 1987)
QB/T 1266  Fur Products  Air Conditioning of Test Pieces for Physical Properties Test
QB/T 1267  Fur Products  Positions and Markings of Sample Pieces
QB/T 1272  Fur Products  General Principles for the Preparation of Chemical Analysis Samples and Chemical Analysis
QB/T 2706  Leather -- Chemical, Physical and Mechanical and Fastness Tests -- Sampling Location (QB/T 2706 - 2005, ISO 2418: 2002, MOD)
QB/T 2707  Leather -- Physical and mechanical Tests--Sample Preparation and Conditioning (QB/T 2707 - 2005, ISO 2419: 2002,MOD)
QB/T 2716  Leather -- Preparation of Chemical Test Samples (QB/T 2716 - 2005, ISO 4044:1977, MOD)

3  Preparation and Standardization of Formaldehyde Stock Solution

3.1  Reagents
Unless otherwise specified only confirmed analytically pure reagent and distilled water or deionized water or the water with equivalent purity are to be used during the analysis. The water shall meet the requirements of Grade 3 in GB/T 6682 - 1992.
3.1.1  Formaldehyde solution, concentration 37%~40%.
3.1.2  0.05M iodine solution (12.68g iodine/L).
3.1.3  2M sodium hydroxide solution.
3.1.4  1.5M sulfuric acid solution.
3.1.5  0.1M sodium thiosulfate solution.
3.1.6  1% starch solution.
3.2  Preparation of Formaldehyde Stock Solution
3.2.1  5 ml of the formaldehyde solution (3.1.1) is pipetted into a 1000 ml volumetric flask which contains approximately 100 ml demineralized water and is subsequently diluted by demineralized water to the mark. This solution is the formaldehyde stock solution.
3.2.2  From this solution, 10 ml is pipetted into a 250 ml Erlenmeyer flask and mixed with 50 ml iodine solution (3.1.2) and sodium hydroxide (3.1.3) is added until it turns yellow. It is allowed to settle for 15 min ± 1 min at 18 °C to 26 °C and then 50 ml of sulphuric acid (3.1.4) is added while swirling. After addition of 2 ml of starch solution (3.1.6), the excess iodine is titrated with sodium thiosulphate (3.1.5) until the color changes. Three individual determinations shall be made.
A blank solution is titrated in the same manner.
3.3  Calculation of Formaldehyde Stock Solution Concentration
a