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GB/T 19941 Leather and fur - Determination of formaldehyde content consists of the following three parts:
——Part 1: High performance liquid chromatography method;
——Part 2: Colorimetric method;
——Part 3: Formaldehyde emissions;
This is part 3 of GB/T 19941.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part has been redrafted and modified in relation to ISO 17226-3: 2011 Leather - Chemical determination of formaldehyde content - Part 3: Method using high performance liquid chromatography.
This part has been changed largely from ISO 17226-3: 2011 in terms of structure. A comparison for the clause numbers in this part and those in ISO 17226-3: 2011 is given in Annex A.
Technical differences have been made in this part with respect to ISO 17226-3: 2011, and relevant technical differences and their causes have been listed in Annex B.
The following editorial changes have been made in this part:
—— the standard name is changed to Leather and fur - Determination of formaldehyde content - Part 3: Formaldehyde emissions;
—— note is added in 6.3 for the operation when the formaldehyde content is too high;
—— the formula symbols are modified;
This part was proposed by China National Light Industry Council.
This part is under the jurisdiction of National Technical Committee 252 on Leather of Standardization Administration of China.
Leather and fur - Determination of formaldehyde content - Part 3: Formaldehyde emissions
1 Scope
This part of GB/T 19941 specifies a method for determining the emission of formaldehyde from leathers. This method is based on high performance liquid chromatography (HPLC).
This standard is applicable to the determination of formaldehyde emission of 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)
QB/T 1266 Fur - Physical and mechanical tests - Sample preparation and conditioning (QB/T 1266-2012, ISO 2419: 2006, MOD)
QB/T 1267 Fur - Chemical, physical and mechanical and fastness tests - Sampling location (QB/T 1267-2012, ISO 2418: 2002, 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 2707 Leather - Physical and mechanical tests - Sample preparation and conditioning (QB/T 2707-2018, ISO 2419: 2012, MOD)
QB/T 2717 Leather - Chemical tests - Determination of volatile matter (QB/T 2717-2018, ISO 4684: 2005, MOD)
3 Principle
A specimen with defined dimensions is held above deionized water in a sealed bottle and is heated at constant temperature for a specific period. Afterwards, the bottle is cooled and the formaldehyde absorbed into the water is analyzed. The water is mixed with 2, 4-dinitrophenylhydrazine, whereby aldehydes and ketones react to give the respective hydrazones. These are separated by means of a reversed-phase HPLC method, detected at specified wavelength and quantified.
4 Reagents and materials
Use only reagents of recognized analytical grade, unless otherwise stated. All solutions are aqueous solutions.
4.1 Water, which shall be of Grade 3 in accordance with GB/T 6682.
4.2 2, 4-Dinitrophenylhydrazine solution, consisting of 0.3 g 2, 4-dinitrophenylhydrazine (DNPH) dissolved in 100 mL concentrated o-phosphoric acid (85 % mass fraction).
4.3 Acetonitrile, chromatographically pure.
5 Apparatus
5.1 Specimen bottle, of capacity 1 L, with hook implement integrated in the lid (see Figure 1). Hook made of stainless steel with seals, is placed in the middle of the lid and does not react with formaldehyde.
5.2 Volumetric flasks, of capacities 10 mL and 500 mL.
5.3 Erlenmeyer flasks, of capacities 100 mL.
5.4 Pipettes, of capacities 1 mL, 5 mL and 50 mL.
5.5 Oven, capable of being maintained at (60 ± 2) °C.
5.6 Analytical balance, weighing to an accuracy of 1 mg.
5.7 HPLC system, equipped with UV detector.
5.8 Press knife, in accordance with QB/T 1266 or QB/T 2707, suitable for cutting specimens of 100 × 40 mm.
5.9 Hole punch for holes of 3 mm to 4 mm in diameter.
5.10 Membrane filter, polyamide, 0.45 μm.
Key:
1—— specimen bottle;
2—— specimen;
3—— deionized water.
Figure 1 Specimen bottle with specimen and water
6 Procedures
6.1 Sampling and preparation and storage of specimens
6.1.1 Sampling
Leather is sampled in accordance with QB/T 2706.
Fur is sampled in accordance with QB/T 1267.
If sampling in accordance with QB/T 2706 or QB/T 1267 is not possible (e.g. leathers from finished products like shoes, garments), provide details about sampling together with the test report.
6.1.2 Preparation of specimen
Sample 5 specimens of 100 mm × 40 mm with the press knife (5.8). To fasten specimens, punch a hole of 3 mm to 4 mm near the centre and 10 mm from the upper edge in each one.
6.1.3 Storage of the specimen
To avoid cross-contamination and loss of formaldehyde during shipment and storage, the leather samples shall be sealed in an inert gastight plastic bag.
Note: Multiple-layer polyethylene bags with a metal layer inside are appropriate.
6.2 Absorption of formaldehyde emission
Weigh the five specimens to the nearest of 0.01 g. Attach them to the hook of specimen bottles (5.1) with 50 mL deionized water respectively, and seal the 5 bottles. Pipette 50 mL aliquots of deionized water into an additional clean specimen bottle. Seal the bottle without a specimen. Use this bottle for a blank test. As soon as the bottles have been sealed, store them for (180 ± 15) min in a heated oven at (60 ± 2) °C. Remove the bottles from the oven and allow them to cool at room temperature for approximately 1 h. Then remove the specimens from the bottles and immediately analyze the formaldehyde absorbed in the water as described in 6.3.
Foreword i
1 Scope
2 Normative references
3 Principle
4 Reagents and materials
5 Apparatus
6 Procedures
7 Result calculation and expression
8 Test report
Annex A (Informative) Structural changes of this part with respect to ISO 17226-3:
Annex B (Informative) Technical differences between this part and ISO 17226-3: 2011 and their causes
Annex C (Normative) Determination of formaldehyde content in standard stock solution
