GB/T 19941.3-2019 PDF English
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Leather and fur -- Determination of formaldehyde content -- Part 3: Formaldehyde emissions
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GB/T 19941.3-2019: PDF in English (GBT 19941.3-2019) GB/T 19941.3-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Leather and fur - Determination of formaldehyde
content - Part 3: Formaldehyde emissions
(ISO 17226-3:2011, Leather - Chemical determination of formaldehyde
content - Part 3: Determination of formaldehyde emissions from leather, MOD)
ISSUED ON: DECEMBER 31, 2019
IMPLEMENTED ON: JULY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Principle ... 6
4 Reagents and materials ... 6
5 Instruments and equipment... 6
6 Test steps ... 7
7 Result calculation and representation ... 9
8 Test report ... 10
Annex A (informative) Structural changes in this Part compared with ISO 17226-
3:2011 ... 11
Annex B (informative) Technical differences between this Part and ISO 17226-
3:2011 and their reasons ... 12
Annex C (normative) Determination of formaldehyde content in standard stock
solution ... 14
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 3 of GB/T 19941.
This Part was drafted in accordance with the rules given in GB/T 1.1-2009.
This Part uses redrafting method by adopting ISO 17226-3:2011 “Leather -
Chemical determination of formaldehyde content - Part 3: Determination of
formaldehyde emissions from leather”.
Compared with ISO 17226-3:2011, this Part has more structural adjustments.
Annex A gives a list of comparisons between this Part and I ISO 17226-3:2011
on chapter numbers.
Compared with ISO 17226-3:2011, there are technical differences in this Part.
Annex B gives a list of corresponding technical differences and their reasons.
This Part also made the following editorial modifications:
- changed the standard name to “Leather and fur - Determination of
formaldehyde content - Part 3: Formaldehyde emissions”;
- added a note on operation when the formaldehyde content is too high in
6.3;
- modified formula symbol.
This Part was proposed by China National Light Industry Council.
This Part shall be under the jurisdiction of National Technical Committee on
Leather Industry of Standardization Administration of China (SAC/TC 252).
The drafting organizations of this Part: Chongqing Testing and Certification
(Group) Co., Ltd., National Leather Quality Supervision and Inspection Center
(Zhejiang), Foshan Nanhai District Jinda Footwear Company Limited, Test
Instruments (Fujian) Co., Ltd., China Leather and Footwear Research Institute
Co., Ltd., Dongguan Huikeda Footwear Company Limited.
Leather and fur - Determination of formaldehyde
content - Part 3: Formaldehyde emissions
1 Scope
This Part of GB/T 19941 specifies high performance liquid chromatography
(HPLC) method for the determination of formaldehyde emission in leather and
fur.
This Part is applicable to determination of formaldehyde emission 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)
QB/T 1266, Leather - 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 (QB/T 2717-
2018, ISO 4684:2005, MOD)
Use the die knife (5.8) to cut 5 samples with a size of 100mm×40mm. In order
to fix the sample, at 10mm from the edge of each sample, make a hole with a
diameter of 3mm~4mm.
6.1.3 Sample storage
To avoid cross-contamination and formaldehyde loss during transportation and
storage, leather and fur samples shall be transported in inert plastic sealed bags.
NOTE: It is recommended to use multi-layer polyethylene plastic bags with metal inner
films.
6.2 Absorption of released formaldehyde
Weigh 5 samples, to the nearest of 0.01g. Respectively place on the hooks in
5 sample bottles (5.1) containing 50mL of water. Seal. Take another sealed
sample bottle that contains only 50mL of water as a blank. After each sample
bottle is sealed, immediately put into a (60±2)°C oven. Place for (180±15) min.
Cool the sample bottle at room temperature for 1h. Take out the sample. The
aqueous solution that contains formaldehyde is immediately tested in
accordance with 6.3.
6.3 Reaction with dinitrophenylhydrazine to develop color
Transfer 4.0mL of acetonitrile (4.3), 5.0mL of aqueous formaldehyde solution
(6.2) and 0.5mL of 2,4-dinitrophenylhydrazine solution (4.2) into a 10mL
volumetric flask. Use distilled water to dilute to the scale. Shake well and place
for 60min~180min. After filtering through a filter membrane (5.10), perform
chromatographic determination.
NOTE: When the formaldehyde content is high (>100mg/kg), it may reduce the amount of
filtrate pipetted. When the pipetted filtrate is less than 5mL, use distilled water to make up
to 5mL (for dilution).
6.4 Chromatographic (HPLC) conditions (recommended)
It shall confirm the reliability of the HPLC test system daily. Follow the steps
specified by the standard curve (6.5) to determine a standard solution with
formaldehyde mass concentration of 2mg/L. Verify the reliability of the method
by recovery rate.
The following chromatographic conditions are recommended chromatographic
conditions:
Flow rate 1.0mL/min
Mobile phase Acetonitrile: water=60:40
Separation column C18 reverse phase column + pretreatment column (1cmPR18)
D - Dilution factor, which is 1 under standard specified conditions; only when
the formaldehyde content in the sample exceeds the detection range of the
standard working curve, it needs to be diluted;
m - Sample mass, in grams (g).
The detection limit of this method is 5.0mg/kg.
If the test result is based on the absolute dry state, the test result shall be
multiplied by the conversion factor 100/(100-w). w is the volatile content (%),
determined according to QB/T 1273 or QB/T 2717.
Take the average of 5 measured values as the calculation result. When the
deviation of the measured value from the average value exceeds 20%, it shall
conduct double sampling to retest. Re-calculate the average of the retest result
and the effective measurement value obtained for the first time.
8 Test report
The test report shall contain the following:
a) Reference to this Part;
b) Sample name, number, type, manufacturer (or trademark);
c) Average amount of formaldehyde released, in milligrams per kilogram
(mg/kg);
d) Total number of test samples;
e) Any deviation from the method specified in this Part;
f) If the test result is based on the absolute dry state, it shall be noted in the
report.
Annex C
(normative)
Determination of formaldehyde content in standard stock solution
C.1 Reagents and materials
C.1.1 Formaldehyde solution: mass fraction is about 37%.
C.1.2 Iodine solution: 0.05mol/L, that is 12.68g/L.
C.1.3 Sodium hydroxide solution: 2.0mol/L.
C.1.4 Sulfuric acid solution: 2.0mol/L.
C.1.5 Sodium thiosulfate solution: 0.1mol/L.
C.1.6 Starch solution: 1%, that is, 1g of starch is dissolved in 100mL of distilled
water.
C.2 Instruments and equipment
C.2.1 Volumetric flask: 1000mL.
C.2.2 Erlenmeyer flask: 250mL.
C.2.3 Pipettes: 5mL, 10mL, 50mL.
C.3 Determination method
C.3.1 Preparation of formaldehyde standard stock solution
Transfer 5.0mL of formaldehyde solution (C.1.1) into a 1000mL volumetric flask
(C.2.1) filled with about 100mL of distilled water. Use distilled water to dilute to
the scale. This solution is formaldehyde standard stock solution.
C.3.2 Determination
Pipette 10mL of formaldehyde standard stock solution into a 250mL conical
flask (C.2.2). Add 50mL of iodine solution (C.1.2). After mixing well, add sodium
hydroxide solution (C.1.3) until it turns yellow. Place in an environment of
18°C~26°C (15±1) min. Then add 15mL of sulfuric acid solution (C.1.4).
Oscillate. Add 2mL of starch solution (C.1.6). Use sodium thiosulfate solution
(C.1.5) to titrate excessive iodine until the color changes (blue disappears).
Conduct three parallel determinations.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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