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GB/T 19941-2005 English PDF (GBT19941-2005)

GB/T 19941-2005 English PDF (GBT19941-2005)

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GB/T 19941-2005: Leather and fur -- Chemical tests -- Determination of formaldehyde content

This standard specifies the method for determining the formaldehyde content in a water extract from leather and fur products. This standard applies to all kinds of leathers, fur products, and their products.
GB/T 19941-2005
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Leather and fur - Chemical tests ?€?
Determination of formaldehyde content
(ISO/TS 17226.2003, Leather - Chemical tests ?€?
Determination of formaldehyde content in leather, MOD)
ISSUED ON. SEPTEMBER 26, 2005
IMPLEMENTED ON. APRIL 01, 2006
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
1 Scope ... 3
2 Normative references ... 3
3 Preparation and standardization of formaldehyde stock solution ... 3 4 Chromatographic HPLC method ... 5
5 Spectrophotometric method ... 8
6 Result expression ... 14
7 Test report ... 14
Appendix A (Informative) Reliability of test methods ... 15
Appendix B (Informative) Clause number comparison between this standard and ISO/TS 17226.2003 ... 16
Appendix C (Informative) Technical differences and causes between this
standard and ISO/TS 17226.2003 ... 18
Leather and fur - Chemical tests ?€?
Determination of formaldehyde content
1 Scope
This standard specifies the method for determining the formaldehyde content in a water extract from leather and fur products.
This standard applies to all kinds of leathers, fur products, and their products. 2 Normative references
The provisions in following documents become the provisions of this Standard through reference in this Standard. For the dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this Standard; however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies. GB/T 6682-1992 Water for analytical laboratory use - Specification and test methods (neq ISO 3696.1987)
QB/T 1266 Leather - Physical and mechanical tests - Sample preparation
and conditioning
QB/T 1267 Fur - Chemical, physical and mechanical and fastness tests -
Sampling location
QB/T 1272 Leather - Chemical tests - Preparation of chemical test samples 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/ 2716 Leather - Preparation of chemical test samples (QB/T 2716-2005, ISO 4044.1977, MOD)
3 Preparation and standardization of formaldehyde
V0 - Titer of the thiosulphate solution for the blank solution, in mL;
V1 - Titer of the thiosulphate solution for the sample solution, in mL; MFA - Molecular weight of formaldehyde, 30.08 g/mol;
c1 - Concentration of the thiosulphate solution, M.
4 Chromatographic HPLC method
4.1 Principle
The process is selective. Formaldehyde is separated and quantified as a derivative from other aldehydes and ketones by liquid chromatography.
Detected is the free formaldehyde and formaldehyde which is hydrolyzed during extraction to yield free formaldehyde.
The sample is eluted with water at 40 ??C. The elute is mixed with 2,4
dinitrophenylhydrazine, whereby aldehydes and ketones react to give the respective hydrazines. They are separated by means of a reversed-phase
HPLC method, detected at 350 nm and quantified.
4.2 Reagent and materials
Unless otherwise stated, it shall only use the reagent of analytical pure, demineralized water or deionized water or the water of equivalent purity, the water shall comply with the level 3 water requirements of GB/T 6682-1992. 4.2.1 0.1% sodium dodecylsulphonate (detergent), 1 g in 1000 mL of water; 4.2.2 0.3% DNPH (2,4-dinitrophenylhydrazine) in concentrated o-Phosphoric acid (85%). (DNPH recrystallized from 25% acetonitrile in water);
4.2.3 Acetonitrile.
4.3 Instrument and equipment
4.3.1 Strainer with glass fiber filter, GF8 (or glass filter strainer G 3, diameter 70 ~ 100 mm);
4.3.2 Water bath, thermostatically controlled to 40 ??C ?? 0.5 ??C, fitted with a flask shaker or stirrer;
4.3.3 Thermometer, with 0.1 ??C graduations over the range 20 ??C to 50 ??C; 4.3.4 HPLC system with UV detection, 350 nm;
CS - Concentration of formaldehyde obtained from the standard curve, in micrograms per 10 milliliters (??g/10 mL);
F - Dilution factor;
EW - Mass of specimen, in grams (g).
4.4.8 Determination of recovery rate
Respectively PIPETTE 2.5 mL of filtered extract (4.4.3) into two 10 mL
volumetric flasks, ADD appropriate amount of formaldehyde standard solution, to make formaldehyde content in the formaldehyde standard solution is almost equal to the formaldehyde content in the sample. ADD 4.0 mL of acetonitrile (4.2.3) and 0.5 mL of DNPH (4.2.2), USE distilled water to dilute it to the mark. CARRY out the determination in accordance with the provisions of clause 4.4.4, INDICATE the formaldehyde content in the sample solution in which the
formaldehyde standard solution is added as CS2, INDICATE the formaldehyde content of the sample solution in which the formaldehyde standard solution is not added as CS. CONDUCT parallel determinations, RECORD the results and average values of the two parallel determinations in the test report. USE the formula (3) to calculate the recovery rate.
Where.
RR - Recovery rate, % (accurate to 0.1%);
CS2 - The formaldehyde content in the sample solution in which the
formaldehyde standard solution is added, in the unit of micrograms per 10 milliliters (??g/10 mL);
CS2 - The formaldehyde content in the sample solution in which the
formaldehyde standard solution is not added, in the unit of micrograms per 10 milliliters (??g/10 mL);
CFA1 - The formaldehyde content in the added formaldehyde standard
solution, in the unit of micrograms per 10 milliliters (??g/10 mL).
5 Spectrophotometric method
5.1 Principles
been heated to 40 ??C, ADD the plug tightly, gently SHAKE the beaker in the 40 ??C ?? 0.5 ??C water bath (4.3.2) for 60 min ?? 2 min. The warm extract solution is immediately filtered by vacuum through a glass fiber filter (4.3.1) into a flask. The filtrate, in a closed flask, is cooled down to room temperature (18 ??C ~ 26 ??C).
Note. the specimen/solution ratio shall not be modified. Extraction and analysis shall be performed within the same working day.
5.4.4 Reaction with acetylacetone
PIPETTE 5 mL of filtrate (5.4.3) into a 25 mL conical flask, ADD 5 mL of acetylacetone solution (5.2.2), ADD the plug. Gently SHAKE the conical flask in the 40 ??C ?? 1 ??C water bath for 30 min ?? 1 min. COOL it down in the dark. USE the mixture of the 5 mL of sodium dodecylsulphonate solution (5.2.1) and 5 mL of acetylacetone solution (5.2.2) as the blank, DETERMINE the
absorbance at 412 nm, which is recorded as Ep.
To determine the absorbance of the extract (5.4.3) itself, TRANSFER 5 mL of filtrate (5.4.3) into a 25 mL conical flask, ADD 5 mL of ammonium acetate solution (5.2.3), then CARRY out determination in accordance with the sample determination method, the corresponding absorbance is recorded as Ee.
Note. when the formaldehyde content is relatively high (> 75 mg/kg), it may reduce the specimen weighing amount; when the pipetted filtrate is less than 5 mL, the distilled water is used to make it reach to 5 mL.
5.4.5 Verification of acetylacetone for absence of formaldehyde
USE the mixture of the 5 mL of sodium dodecylsulphonate solution (5.2.1) and 5 mL of water as the blank, USE a 20 mm cuvette to determine the absorbance of the mixture of the 5 mL of sodium dodecylsulphonate solution (5.2.1) and 5 mL of acetylacetone solution (5.2.2) at the 412 nm. If the determined
absorbance is not more than 0.025, it indicates that ther...

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