Textiles - Determination of the banned azo colourants
WARNING——Persons using this document shall be familiar with normal laboratory practice. This document does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.
1 Scope
This document describes a method to determine the use of banned azo colourants in textile products that can decompose the carcinogenic aromatic amines listed in Annex B.
It applies to coloured textile products processed by dyeing, printing and coating.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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 23344 Textiles - Determination of 4-aminoazobenzene
3 Terms and definitions
No terms and definitions are listed in this document.
4 Principle
Under the specified conditions, the test specimen is placed in a citrate/sodium hydroxide buffer solution, and then reduced and cleaved with sodium dithionite to produce possible aromatic amines. Afterwards, any aromatic amine released in the process is transferred to t-butyl methyl ether by means of extraction using diatomaceous earth columns. The t-butyl methyl ether extract is then concentrated, and the residue is taken up in an appropriate solvent for determination of the aromatic amines using chromatography (see Annex C). If any aromatic amine is detected, then confirmation shall be made using one or more alternative chromatographic techniques.
Note: A screening method using liquid-liquid extraction without diatomaceous earth columns is described in Annex D.
5 Reagents and materials
Unless otherwise specified, analytical grade reagents shall be used.
5.1 Grade 3 water, complying with GB/T 6682.
5.2 Chromatographic grade acetonitrile.
5.3 Chromatographic grade methanol.
5.4 Analytical grade t-butyl methyl ether.
5.5 Citrate/sodium hydroxide buffer solution, c=0.06mol/L, pH=6.0.
5.6 Aqueous sodium dithionite solution, with an effective concentration of 200mg/mL, to be used within 1h after preparation.
5.7 Diatomaceous earth, porous and granular, burned at 600℃ for 4h, cooled and stored in a dryer for later use.
5.8 Aromatic amine standards: aromatic amines 1~24 (see Table B.1 in Annex B), and aniline and 1,4-phenylenediamine——all of highest available defined purity standards.
5.9 Standard solutions, see 5.9.1~5.9.5.
5.9.1 Standard stock solution of aromatic amines, with a mass concentration of equal to or greater than 300μg of each aromatic amine per millilitre of acetonitrile or an appropriate solvent.
Note: This standard stock solution shall be kept in a brown bottle with a small amount of anhydrous sodium sulfite, and shall be stored in the freezer of a refrigerator, with a shelf life of one month.
5.9.2 Standard working solution of aromatic amines, diluted from the standard stock solution of aromatic amines (see 5.9.1) to a mass concentration of 15μg/mL of each aromatic amine with acetonitrile or an appropriate solvent, freshly prepared.
5.9.3 Standard working solution of aromatic amines for quantification, with a mass concentration range from 2μg/mL to 50μg/mL of each aromatic amine, diluted from the standard stock solution of aromatic amines (see 5.9.1) with acetonitrile or an appropriate solvent, freshly prepared. If GC-MS is used for quantitative analysis, 10μL of internal standard solution (see 5.9.4) per millilitre must be added before injection. This solution shall be freshly prepared.
Note: Appropriate concentrations shall be chosen for establishing the calibration curve.
5.9.4 Internal standard solution (IS), ρ=1.0mg/mL in the appropriate solvent.
In the case of GC-MS analysis, one of the following internal standards may be used:
——IS1: naphthalene-d8, CAS No.: 1146-65-2;
——IS2: 2,4,5-trichloroaniline, CAS No.: 636-30-6;
——IS3: anthracene-d10, CAS No.: 1719-06-8.
5.9.5 Benzidine-d8, CAS No.: 92890-63-6.
It is prepared into a solution with a mass concentration of 0.5mg/mL with the internal standard solution (see 5.9.4). Benzidine-d8 is a suitable indicator for aromatic amine peaks in the later part of the GC chromatogram (see 8.3).
5.10 Sodium hydroxide aqueous solution, a mass fraction of 10%.
6 Apparatus
6.1 Reaction vessel (20mL~50mL) of heat-resistant glass, with tight closure.
6.2 Constant temperature heater that can control the temperature at (70±2)℃.
6.3 Glass or polypropylene column, inside diameter 25mm~30mm, length 130mm~150mm, packed with about 20g of diatomaceous earth (see 5.7), fitted with glass fibre filter at the outlet The diatomaceous earth columns are either bought pre-packed and used as is, or 20g of diatomaceous earth can be packed into a glass or polypropylene column.
6.4 Vacuum rotary evaporator with vacuum control and water bath. Other kinds of evaporation apparatus may be used, e.g. a nitrogen blower with water bath and nitrogen flow control.
6.5 Pipettes in required sizes or variables pipettes.
6.6 Chromatographic equipment, selected from the following:
6.6.1 High-performance liquid chromatograph (HPLC) with diode array detector (DAD) or mass selective detector (MS).
6.6.2 Gas chromatograph (GC) with mass selective detector (MS).
6.7 Polytetrafluoroethylene (PTFE) filter membrane with pore sizes of 0.22μm, 0.45μm or other applicable specifications.
Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents and materials
6 Apparatus
7 Test specimen sampling and preparation
8 Test procedures
9 Calculation and expression of results
10 Test report
Annex A (Informative) Technical differences between this document and ISO 14362-1:2017
Annex B (Normative) Carcinogenic aromatic amines
Annex C (Informative) Chromatographic analyses
Annex D (Informative) Procedure for liquid-liquid extraction without diatomaceous earth column
Annex E (Informative) Assessment guide - analysis and interpretation of results
Annex F (Informative) Pigments
Annex G (Informative) Textiles - Determination of the banned azo colourants - Extraction method
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