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GB/T 19941.1-2019 English PDF (GBT19941.1-2019)

GB/T 19941.1-2019 English PDF (GBT19941.1-2019)

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GB/T 19941.1-2019: Leather and fur -- Determination of formaldehyde content -- Part 1: High performance liquid chromatography method
This Part of GB/T 19941 specifies high performance liquid chromatography method (HPLC) to determine free and hydrolyzed formaldehyde content in leather and fur. This Part is applicable to the determination of formaldehyde content in various leather, fur and their products.
GB/T 19941.1-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Partially replacing GB/T 19941-2005
Leather and fur - Determination of formaldehyde
content - Part 1: High performance liquid
chromatography method
(ISO 17226-1:2018, Leather - Chemical determination of formaldehyde
content - Part 1: Method using high performance liquid chromatography,
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 ... 6
2 Normative references ... 6
3 Principle ... 7
4 Reagents and materials ... 7
5 Instruments and equipment... 7
6 Test steps ... 8
7 Result representation ... 11
8 Test report ... 11
Annex A (informative) Structural changes in this Part compared with ISO 17226- 1:2018 ... 12
Annex B (informative) Technical differences between this Part and ISO 17226- 1:2018 and the reasons ... 13
Annex C (normative) Determination of formaldehyde content in standard stock solution ... 15
Leather and fur - Determination of formaldehyde
content - Part 1: High performance liquid
chromatography method
1 Scope
This Part of GB/T 19941 specifies high performance liquid chromatography method (HPLC) to determine free and hydrolyzed formaldehyde content in
leather and fur.
This Part is applicable to the determination of formaldehyde content in various leather, fur 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/T6682-2008, ISO3696:1987, MOD)
GB/T 19941.2, Leather and fur - Determination of formaldehyde content - Part 2: Colorimetric method (GB/T 19941.2-2019, ISO 17226-2:2018, MOD)
QB/T 1267, Fur - Chemical, physical and mechanical and fastness tests - Sampling location (QB/T 1267-2012, ISO 2418:2002, MOD)
QB/T 1272, Leather - Chemical tests - Preparation of chemical test samples (QB/T 1272-2012, ISO 4044:2008, 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 2716, Leather - Preparation of chemical test samples (QB/T 2716-2018, ISO 4044:2008, MOD)
5.5 Thermometer: range is 0°C~100°C, division value is 0.1°C.
5.6 High performance liquid chromatography system (HPLC): equipped with ultraviolet detector (UV), wavelength is (355±5) nm.
5.7 Polyamide filter membrane: 0.45μm.
5.8 Analytical balance: accuracy is 0.1mg.
6 Test steps
6.1 Sampling and sample preparation
6.1.1 Sampling
Leather is sampled in accordance with QB/T 2706.
Fur is sampled in accordance with QB/T 1267.
If the sample cannot be sampled in accordance with the requirements of QB/T 2706 or QB/T 1267 (such as shoe uppers, leather on leather clothing), the sampling process shall be indicated in the report.
6.1.2 Sample preparation
The preparation of leather sample is carried out in accordance with QB/T 2716. The preparation of fur sample is carried out in accordance with QB/T 1272. During the sample preparation process, try to keep the coat intact to avoid damage to the coat.
6.2 Extraction
Weigh (2.0±0.1) g of sample, to the nearest of 0.01g. Put it in a 100mL Erlenmeyer flask. Add 50mL of extraction solution that has been preheated to 40°C (4.2). Close the stopper tightly. Gently shake (60±2)min in a water bath at (40±1)°C. The warm extract is immediately filtered through a glass fiber filter vacuum (vacuum degree is not less than 5kPa) into another Erlenmeyer flask. After sealing, cool the filtrate in the Erlenmeyer flask to room temperature (18°C~26°C).
NOTE: The sample/solution ratio cannot be changed. Extraction and analysis are completed on the same day.
6.3 Reaction with 2,4-dinitrophenylhydrazine
Transfer 4.0mL of acetonitrile (4.4), 5mL of filtered extract (6.2) and 0.5mL of Use the peak area as the Y-axis and the formaldehyde mass concentration (μg/10mL) as the X-axis to draw a formaldehyde standard working curve.
6.5.2 Drawing with 2,4-dinitrophenylhydrazine-formaldehyde derivative
In 6 10mL volumetric flasks, respectively add 4mL of acetonitrile (4.4). Then respectively add appropriate amount of 2,4-dinitrophenylhydrazine-
formaldehyde derivative to obtain standard working solutions respectively containing 1.0μg, 4.0μg, 8.0μg, 12.0μg, 16.0μg and 20.0μg of formaldehyde. Use distilled water to dilute to the scale. Shake well. Place 60min~180min. After filtering through the filter membrane (5.7), perform chromatographic analysis. Use the peak area as the Y axis and the mass concentration of formaldehyde (μg/10mL) as the X axis to draw a standard curve.
6.6 Calculation of formaldehyde content in leather and fur samples
Calculate the content of formaldehyde in the sample according to formula (1): Where,
wF - Formaldehyde content in the sample, in milligrams per kilogram (mg/kg); ms - Formaldehyde content in 10mL of color developing solution (6.3) obtained from the standard curve, in micrograms (μg);
F - Dilution factor;
m - Sample mass, in grams (g).
6.7 Determination of recovery rate
When necessary, test the recovery rate of standard addition as follows. Transfer 2.5 mL of the filtered extract (6.2) into a 10mL volumetric flask containing 4.0mL of acetonitrile (4.4). Then add an appropriate amount of formaldehyde standard solution to the volumetric flask to make the
formaldehyde content in the added formaldehyde standard solution almost equal to the formaldehyde content in the sample. Perform chromatographic analysis according to 6.3. The mass concentration of formaldehyde in the sample solution added with formaldehyde standard solution is recorded as ρs2. Record the results of the test in the test report. Calculate the recovery rate according to formula (2):
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.
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) that is filled with about 100mL of distilled water. Use distilled water to dilute to the scale. This solution shall be formaldehyde standard stock solution. C.3.2 Determination
Pipette 10mL of formaldehyde standard stock solution into a 250mL Erlenmeyer 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. Then add 2mL of starch solution (C.1.6). Excess iodine is titrated with sodium thiosulfate solution (C.1.5) until the color changes. Perform three parallel determinations.
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