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This standard is developed 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 colorants.
Main technical changes have been made as follows, with respect to GB/T 19942-2005:
—The reference to the year of GB/T 6682 has been removed from and reference to “GB/T 33392” has been introduced to the normative references (see Clause 2; Clause 2 of 2005 edition);
—The specific test conditions have been removed from and an amine determination method has been introduced to the clause of “Principle” (see Clause 4; Clause 4 of 2005 edition);
—A requirement for methanol purity has been introduced (see 5.2);
—Ethyl acetate has been introduced (see 5.3);
—A purity requirement and explanatory note for t-butyl methyl ether have been introduced (see 5.4);
—A requirement for the standing time of prepared sodium dithionite solution has been introduced (see 5.6);
—The preheated temperature requirement for citrate buffer solution (see 5.11; 6.9 of 2005 edition);
—The types of chromatographic equipment have been modified in the clause “Apparatus” (see 6.12; 5.11 of 2005 edition);
—A requirement for sampling in the case of patchwork fabrics with varicolored patterns, various leather and fur qualities has been introduced (see 7.1);
—A range of room temperature for reductive cleavage has been introduced (see 8.2);
—A filter process before chromatographic analysis has been introduced to liquid-liquid extraction (see 8.3);
—A requirement that analysis of standard solution for process control shall be carried out with each batch of specimens has been introduced (see 8.5; Clause 9 of 2005 edition);
—The chromatographic analysis parameters have been moved to Annex C and parameters for liquid chromatography have been introduced (see Annex C; 10.1 of 2005 edition);
—The symbols in calculation formula have been modified (see clause 9; clause 11 of 2005 edition);
—“Feasibility of the method” has been moved to Clause 10 and a description for aromatic amines numbers 5, 6, and 22 have been introduced (see Clause 10; 8.4 of 2005 edition);
—The contents of test report have been modified (see Clause 11; Clause 12 of 2005 edition).
This standard is a redraft based on modified adoption of 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.
This standard is changed largely from ISO 17234-1:2015 in terms of structure. See Annex A for cross references to the clauses/subclauses between this standard and ISO 17234-1:2015.
Technical differences have been made in this standard with respect to cross reference, and have been listed together with the justification in Annex B.
For the convenience of users, this standard includes editorial changes as follows:
—The standard name has been changed to Leather and fur—Chemical tests—Determination of banned azo colorants;
—The example of the suitable product type in the note of “6.5 Polypropylene or glass column” of ISO17234-1: 2015 has been removed and a note of commercially available column has been introduced;
—A note has been introduced to “7.2 t-butyl methyl ether” of ISO 17234-1: 2015;
—A note “if the detected amount ... is over 30 mg/kg, it shall be assumed that the specimen submitted has been manufactured or treated using a certain banned azo colorants was used” has been introduced to 9.2;
—A GC/MS total ion chromatogram of aromatic amine reference has been introduced to Annex A of ISO 17234-1:2015;
—Annex B and Annex C of ISO 17234-1:2015 have been removed.
This standard was proposed by the China National Light Industry Council.
This standard is under the jurisdiction of the National Technical Committee on Leather of Standardization Administration of China (SAC/TC 252).
The previous edition of this standard is as follows:
—GB/T 19942-2005.
Leather and fur—Chemical tests—
Determination of banned azo colorants
Warning: Users of this standard shall be experienced in normal laboratory practicing. Aromatic amines are classified as substances known to be or suspected to be human carcinogens. This standard does not purport to address possible safety issues exhaustively. It is the user’s responsibility to use safe and proper techniques and guarantee compliance with the appropriate national and local laws and regulations.
1 Scope
This standard specifies a method for determining banned azo colorants, which can release carcinogenic aromatic amines, derived from dyed leather and fur.
This standard applies to the determination of banned azo colorants in various dyed 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)
GB/T 33392 Leather and fur—Chemical tests—Determination of 4-aminoazobenzene in banned 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)
QB/T 2716 Leather—Preparation of chemical test samples (QB/T 2716-2018, ISO 4044:2008, MOD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
banned azo colorants
colorants that can release, by reductive cleavage of azo group(s), one or more of the aromatic amines listed in Table 1
Table 1 24 carcinogenic aromatic amines
No. Aromatic amine CAS No.
1 4-aminodiphenyl 92-67-1
2 benzidine 92-87-5
3 4-chloro-o-toluidine 95-69-2
4 2-naphthylamine 91-59-8
5a 2-aminoazotoluene 97-56-3
6a 2-amino-4-nitrotoluene 99-55-8
7 p-chloroaniline 106-47-8
8 2,4-diaminoanisole 615-05-4
9 4,4'-diaminodiphenylmethane 101-77-9
10 3,3'-dichlorobenzidine 91-94-1
11 3,3'-dimethoxybenzidine 119-90-4
12 3,3'-dimethylbenzidine 119-93-7
13 3,3'-dimethyl-4,4'-diaminodiphenylmethane 838-88-0
14 p-cresidine 120-71-8
15 4,4'-methylene-bis-(2-chloroaniline) 101-14-4
16 4,4'-oxydianiline 101-80-4
17 4,4'-thiodianiline 139-65-1
18 o-toluidine 95-53-4
19 2,4-toluylenediamine 95-80-7
20 2,4,5-trimethylaniline 137-17-7
21 2-anisidine 90-04-0
22b 4-aminoazobenzene 60-09-3
23 2,4-xylidine 95-68-1
24 2,6-xylidine 87-62-7
a As shown by this method, 2-aminoazotoluene (CAS-number 97-56-3, No. 5) and 2-amino-4-nitrotoluene (CAS-number 99-55-8, No. 6) are further reduced to o-toluidine (CAS-number 95-53-4, No. 18) and 2,4-toluylenediamine (CAS-number 95-80-7, No. 19).
b As shown by this method, 4-aminoazobenzene (No. 22, CAS number 60-09-3) is able to form aniline and/or 1,4-phenylenediamine. The presence of aniline and/or 1,4-phenylenediamine shall necessitate a retest using GB/T 33392.
4 Principle
After degreasing, the specimen is treated with sodium dithionite in an aqueous buffer solution (specified pH) at a certain temperature in a closed vessel. The aromatic amines released in the process of reductive cleavage are transferred to a t-butyl methyl ether phase by means of liquid-liquid extraction using Kieselgur columns. The t-butyl methyl ether extract is then concentrated and the residue is dissolved in a suitable solvent until volume is made up. Determination of the amines is performed by means of high-performance liquid chromatography (HPLC) using a diode array detector (DAD) or mass selective detector (HPLC/MS), capillary gas chromatography with a mass-selective detector (GC-MS) or by capillary electrophoresis with a diode array detector (CE/DAD), or qualitatively with thin layer chromatography (TLC, HPTLC).
The amines shall be identified by means of at least two different chromatographic separation methods in order to avoid any possible misinterpretations caused by interfering substances (such as position isomers of the amines to be identified) and hence any incorrect statements. Amine quantification shall be performed by HPLC/DAD or GC/MS.
5 Reagents and materials
Use only reagents of recognized analytical grade, unless otherwise stated. All solutions are aqueous solutions.
5.1 Water, Grade 3 according to GB/T 6682, for test purpose.
5.2 Methanol: Chromatographic grade.
5.3 Ethyl acetate: Chromatographic grade.
5.4 t-butyl methyl ether: Analytical grade.
Note: t-butyl methyl ether of analytical grade may contain impurities that can react with the aromatic amines released in the process of reductive cleavage, resulting in detection failure or undervaluation of a positive specimen. It is recommended to evaporate t-butyl methyl ether for purification before use, or to use reagent of chromatographic grade.
5.5 Sodium dithionite, minimum 87% purity.
5.6 Aqueous sodium dithionite solution, 200 mg/ml, freshly prepared, to be used immediately after resting for 1 h in a closed vessel.
5.7 n-hexane.
5.8 Aromatic amine standards: listed in Table 1 (highest available purity standard).
5.9 Stock solution of the amines (5.8): 400 mg/l in ethyl acetate for TLC.
5.10 Stock solution of the amines (5.8): 200 mg/l in methanol for GC, HPLC, CE.
5.11 Citrate buffer solution, 0.06 mol/l, pH = 6, preheated to (70 ± 5) °C.
5.12 Standard solution for amine process control: 30 µg amine per milliliter solvent, freshly prepared from stock solutions 5.9 or 5.10 depending on the analytical method.
5.13 20% methanolic NaOH solution, 20 g NaOH dissolved in 100 ml methanol.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents and materials
6 Apparatus
7 Sampling and preparation of specimens
8 Test procedure
9 Calculation and expression of results
10 Feasibility of the method
11 Test report
Annex A (Informative) Structural changes of this standard with reference to ISO 17234-1:
Annex B (Informative) Technical differences between this standard and ISO 17234-1:2015, and justification
Annex C (Informative) Chromatographic analyses
