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GB/T 19942-2019 English PDF (GBT19942-2019)

GB/T 19942-2019 English PDF (GBT19942-2019)

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GB/T 19942-2019: Leather and fur -- Chemical tests -- Determination of banned azo colorants

This Standard specifies the determination method for banned azo colorants that can release carcinogenic aromatic amines in dyed leather and fur. This Standard is applicable to the determination of banned azo colorants in various dyed leather, furs and their products.
GB/T 19942-2019
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Replacing GB/T 19942-2005
Leather and fur - Chemical tests - Determination of
banned azo colorants
(ISO 17234-1:2015, Leather - Chemical tests for the determination of
certain azo colorants in dyed leathers - Part 1: Determination of certain aromatic amines derived from azo colorants, MOD)
ISSUED ON: DECEMBER 31, 2019
IMPLEMENTED ON: JULY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 7
4 Principle ... 8
5 Reagents and materials ... 8
6 Apparatus ... 9
7 Sampling and preparation of samples ... 10
8 Test procedure ... 11
9 Calculation and expression of results ... 12
10 Method feasibility ... 13
11 Test report ... 14
Annex A (Informative) Structural changes of this Standard compared with ISO 17234-1:2015 ... 15
Annex B (Informative) Technical differences between this Standard and ISO 17234-1:2015 and their reasons ... 16
Annex C (Informative) Chromatographic analyses ... 18
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009. This Standard replaces GB/T 19942-2005 "Leather and fur - Chemical tests - Determination of banned azo colourants".
Compared with GB/T 19942-2005, the main technical changes of this Standard are as follows:
- In "Normative references", delete the year number cited to GB/T 6682; ADD the reference to "GB/T 33392" (see Clause 2; Clause 2 of the 2005 edition); - In "Principle" clause, delete specific test conditions; ADD the method for determination of amine (see Clause 4; Clause 4 of the 2005 edition);
- ADD the purity requirement for methanol (see 5.2);
- ADD ethyl acetate (see 5.3);
- ADD the purity requirement and descriptive note for tert-butyl methyl ether (see 5.4);
- ADD the requirement for the storage time after the preparation of sodium dithionite solution (see 5.6);
- Modify the pre-heating temperature requirement for citrate buffer (see 5.11; 6.9 of the 2005 edition);
- In "Apparatus", modify the types of chromatographic analysis equipment (see 6.12; 5.11 of the 2005 edition);
- ADD the requirements for sampling of printed and multi-color splicing samples, and samples composed of leather and fur of different qualities (see 7.1);
- In reductive cleavage, add the temperature range of room temperature (see 8.2);
- In the liquid-liquid extraction, add the filtration operation of the solution before chromatographic analyses (see 8.3);
- ADD the requirement that each batch of samples be analyzed respectively with standard working solution (see 8.5; Clause 9 of the 2005 edition); - Adjust the chromatographic analysis parameters to Annex C; ADD liquid Leather and fur - Chemical tests - Determination of
banned azo colorants
WARNING - The personnel using this Standard shall have practical
experience in regular laboratory work. The aromatic amines are classified as substances known to be or suspected to be human carcinogens. This
Standard does not point out all possible safety problems. It is the
responsibility of the user to take appropriate safety and health measures and ensure compliance with the conditions of relevant national and local laws and regulations.
1 Scope
This Standard specifies the determination method for banned azo colorants that can release carcinogenic aromatic amines in dyed leather and fur.
This Standard is applicable to the determination of banned azo colorants in various dyed leather, furs and their products.
2 Normative references
The following documents are indispensable for the application of this document. For the dated references, only the editions with the dates indicated are applicable to this document. For the undated references, the latest edition (including all the amendments) are applicable to this document.
GB/T 6682 Water for analytical laboratory use - Specification and test
methods (GB/T 6682-2008, ISO 3696:1987, MOD)
GB/T 33392 Leather and fur - Chemical tests - Determination of 4-
aminoazobenzene derived from azo colorants (GB/T 33392-2016, ISO
17234-2:2011, 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 Fur - Preparation of chemical test samples (QB/T 1272-2012, ISO 4044:2008, MOD)
QB/T 2706 Leather - Chemical, physical and mechanical and fastness tests - Sampling location (QB/T 2706-2005, ISO 2418:2002, MOD)
Note: The impurities, which may be contained in analytical-grade tert-butyl methyl ether, will react with the aromatic amine after reduction and cleavage; resulting in the positive samples not detected or too small detected amount. Therefore, it is recommended to distill and purify tert-butyl methyl ether before use or directly use chromatographically-pure reagent.
5.5 Sodium dithionite; purity is ???87%.
5.6 Aqueous sodium dithionite solution, 200 mg/mL. Freshly prepare and use it immediately after placing it in a closed vessel for 1 h.
5.7 N-hexane.
5.8 Aromatic amine standards. See Table 1; highest purity.
5.9 Aromatic amine (5.8) stock solution, 400 mg/L. Solvent is ethyl acetate; used for TLC analysis.
5.10 Aromatic amine (5.8) stock solution, 200 mg/L. Solvent is methanol; used for GC, HPLC or CE analysis.
5.11 Citrate buffer, 0.06 mol/L; pH=6, preheated to (70??5)??C.
5.12 Aromatic amine standard working solution; the mass concentration of aromatic amine is 30 ??g/mL. According to the analysis method, it is freshly prepared from aromatic amine stock solution (5.9) or (5.10).
5.13 20% sodium hydroxide methanol solution; 20 g of sodium hydroxide is dissolved in 100 mL of methanol.
6 Apparatus
6.1 Suitable glass reactor, high-temperature resistant and sealable.
6.2 Constant-temperature water bath or sand bath (sea sand; particle size is 0.1 mm~0.3 mm), with temperature control device.
6.3 Thermometer; it can be accurate to 0.5 ??C at 70 ??C.
6.4 Volumetric flasks, different specifications.
6.5 Extraction column, polypropylene or glass column. Inner diameter is 25 mm~30 mm; length is 140 mm~150 mm. The end is equipped with porous
granular kieselguhr (about 20 g; lightly tap the glass column to make the packing firm).
Leather: It shall be in accordance with the provisions of QB/T 2716.
Fur: It shall be in accordance with the provisions of QB/T 1272. In the process of sample preparation, it shall avoid damaging the coat and keep the coat intact. It shall remove the glue and attachments on the surface of the sample as cleanly as possible; mix the sample evenly; and put it into a clean sample bottle for testing.
8 Test procedure
8.1 Degreasing
WEIGH 1.0 g of the cut sample into a 50 mL glass reactor (6.1); ADD 20 mL of n-hexane (5.7) and cover the stopper; PLACE it in an ultrasonic bath (6.9) at (40??2)??C for 20 min; decant the n-hexane (be careful not to lose the sample). USE 20 mL of n-hexane to treat it again in the same way. The degreased
sample is placed overnight in an open vessel, to completely volatilize the n- hexane.
8.2 Reductive cleavage
After the n-hexane in the sample is completely volatilized, add 17 mL of citrate buffer (5.11) preheated to (70??5)??C, and cover the stopper. Gently shake to make the sample wet; in a fume hood, place it in a water bath (or sand bath) preheated to (70??2)??C and heat it for (25??5)min. The inside of the reactor is always kept at 70 ??C.
USE a syringe (6.6) to add 1.5 mL of sodium dithionite solution (5.6); KEEP at 70 ??C and heat for 10 min. Then add 1.5 mL of sodium dithionite solution; continue to heat for 10 min, take out. PUT the reactor into cold water and cool to room temperature (20 ??C~25 ??C) within 2 min.
8.3 Liquid-liquid extraction
USE a glass rod to squeeze the fiber material in the reactor as much as possible; carefully transfer all the lysis solution to the kieselguhr extraction column (6.5); and allow to be absorbed for 15 min. ADD 5 mL of tert-butyl methyl ether (5.4) and 1 mL of 20% sodium hydroxide methanol solution (5.13) into the reactor with the sample; tighten the lid; after sufficient shaking, immediately transfer the solution to the extraction column (6.5).
Respectively use 15 mL and 20 mL of tert-butyl methyl ether to rinse the reactor and sample twice; and transfer all the washing liquid to the kieselguhr extraction column (6.5). Then, add 40 mL of tert-butyl methyl ether (5.4) to the extraction Ac - The peak area of aromatic amine in standard working solution;
V - The final sample constant volume after treatment according to 8.3, in milliliters (mL); it is 2 mL under standard conditions;
mE - The mass of sample, in grams (g).
9.2 Expression of results
According to the following recognition threshold, list and report separately: a) When the content of each aromatic amine component is ???30 mg/kg, the
test report shall indicate "Under the specified test conditions, no
carcinogenic aromatic amine listed in the standard is detected in the
sample". This means that, the banned azo colorants that can release the listed carcinogenic aromatic amines cannot be detected;
b) When the content of an aromatic amine component is >30 mg/kg, the test report shall indicate "Under the specified test conditions, the carcinogenic aromatic amine listed in the standard is detected in the sample"; and shall write the name of the aromatic amine. This means that, the sample used
banned azo colorants during production and treatment;
c) When the content of 4-aminodiphenyl and/or 2-naphthylamine is >30
mg/kg, based on current scientific knowledge, without other evidence, it cannot be unequivocally confirmed that banned azo colorants were used.
Note: According to the existing scientific knowledge, when dyed leather and fur are cleaved under the conditions of this test method and produce one or more of the aromatic amines listed in Table 1, and after testing, the content exceeds 30 mg/kg; then the sample is deemed to have used banned azo colorants during processing and treatment.
10 Method feasibility
The feasibility of the method is expressed by the recovery rate. TAKE 1.0 mL of aromatic amine standard solution (5.12); ADD it to the reactor (6.1) containing 16 mL of preheated citrate buffer (5.11); then, perform analysis according to the operation steps for treating samples (see 8.2 and 8.3). The recovery rate of aromatic amines shall meet the following requirements:
- The recovery rate of aromatic amines numbered 1~4, 7, 9~17 and 20~21
in Table 1 shall be greater than 70%;
- The recovery rate of aromatic amine numbered 8 in Table 1 shall be greater Annex C
(Informative)
Chromatographic analyses
C.1 General
As the instrumental equipment (6.12) of the laboratories may be different, it is impossible to provide a general chromatographic analysis operation guide. The following parameters have been proved to be feasible.
C.2 High-performance liquid chromatography (HPLC)
C.2.1 High-performance liquid chromatography/diode array detector
(HPLC/DAD)
Mobile phase 1: Methanol;
Mobile phase 2: 0.575 g of ammonium dihydrogen phosphate + 0.7 g of
disodium hydrogen phosphate are dissolved in 1000 mL of water; pH=6.9;
Stationary phase: LiChrospher 60 RP-select B (5 ??m); 250 mm??4.6 mm;
Flow rate: 0.7 mL/min~1.0 mL/min;
Gradient: Start: 15% mobile phase 1, linear increase to 80% mobile phase 1 within 45 min;
Column temperature: 40 ??C;
Injection volume: 10.0 ??L;
Detector: DAD;
Quantification: Determine at 240 nm, 280 nm and 305 nm.
C.2.2 High-performance liquid chromatography/mass selective detector
(HPLC/DAD/MS)
Mobile phase 1: Acetonitrile;
Mobile phase 2: 5 mmol of ammonium acetate is dissolved in 1000 mL of
water; pH=3.0;
Stationary phase: Zorbax Eclipse XDB C18 (3.5 ??m); 50 mm??2.1 mm;
Capillary 2: 56 cm; the coating is polyvinyl alcohol (PVA); inner diameter is 50 ??m; with extended light path;
Buffer: Phosphate buffer (c=50 mmol/L); pH=2.5;
Column temperature: 25 ??C;
Voltage: 30 kV;
Injection time: 4 s;
Rinse time: 5 s;
Detector: DAD; 214 nm, 240 nm, 280 nm, 305 nm.
C.5 Thin-layer chromatography (TLC); HPTLC or TLC only for
semiquantitative confirmation
C.5.1 Thin-layer plate (HPTLC)
Thin-layer plate (HPTLC): Silica gel 60, containing fluorescent indicator F254; 20 cm??10 cm;
Injection volume: 5 ??L, applied as a line with automatic applicator;
Mobile phase 1: Chloroform : glacial acetic acid=90 : 10 (volume ratio). C.5.2 Thin-layer plate (TLC)
Thin-layer plate (TLC): Silica gel 60, 20 cm??10 cm; saturated chamber;
Injection volume: 10 ??L, applied as a line with automatic applicator;
Mobile phase 2: Chloroform : ethyl acetate : acetic acid=60 : 30 : 10 (volume ratio).
Mobile phase 3: Chloroform : methanol=95 : 5 (volume ratio).
Mobile phases 2 and 3: Successively without drying of the plates.
C.5.3 Detection
Detection: 1. Ultraviolet (UV) lamp;
2. After treatment with reagents 2 and 3, reaction time is
approximately 5 min;
Reagent 1: 0.1% NaNO2 is dissolved in 1 mol/L KOH solution;

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