Azo dyes, accessible without extraction of the reducing agent, are substances used to color with pigments or dye:
Extraction-accessible azo dyes are those used to dye man-made fibers with disperse dyes. The following man-made fibers can be dyed with disperse dyes: polyester, polyamide, acetate, triacetate, acrylic, and chlorofiber.
The method described in this standard is valid for all colored textiles such as dyed, printed and coated textiles.
Some azo dyes may release one or more of the aromatic amines listed in the table titled “Targeted aromatic amines” by reductive cleavage of the azo groups.
After selecting a colored test sample from a textile, the test sample is tested using the colorant extraction method for disperse dyes or the direct reduction method for other colorant classes (pigments and dyes). The application of either method depends on the nature of the test sample's fibers (whether pure fiber or fiber blends) and the color process (dyeing or printing).
When using the colorant extraction method for disperse dyes, the colorant is first extracted from the fiber in the headspace using xylene under reflux. The extract is concentrated and transferred to a reaction vessel containing methanol for subsequent reduction with sodium dithionite in a citrate-buffered aqueous solution (pH = 6) at 70°C. If the textile sample is not completely decolorized after the xylene extraction, a new test sample must be prepared and reprocessed using the method for the non-removable classes of colorants.
When performing the method for non-removable colorant classes, the test sample is treated with sodium dithionite in a citrate-buffered aqueous solution (pH = 6) at 70°C in a closed container. After reduction, any amines released in the process are transferred to a t-butyl methyl ether phase by liquid-liquid extraction using diatomaceous earth columns. The t-butyl methyl ether extract is then concentrated, and the residue is taken up in a suitable solvent for amine detection and identification using chromatography.
A screening method using liquid-liquid extraction without diatomaceous earth columns is described in Appendix E. If any amine is detected by a chromatographic method, then confirmation should be made using one or more alternative methods.
EN ISO 14362-1 is an international standard that specifies a method for detecting certain carcinogenic azo dyes in textiles. These dyes can release aromatic amines that are harmful to human health. The aim of this standard is to ensure that textiles, particularly those in direct contact with human skin, are free of limited azo dyes that can degrade into carcinogenic aromatic amines.
This standard applies to all types of textile fibers. It covers both extractable and non-extractable colorants (i.e., controls both dyes that can and cannot be removed from textiles). It is used to screen for and verify the presence of prohibited aromatic amines released from azo dyes.
This standard targets 22 specific aromatic amines restricted by European regulations such as REACH. Azo dyes that can degrade to these amines under reducing conditions are considered hazardous.
Typical methods include:
This standard is widely used for compliance with bans on hazardous chemicals in apparel and home textiles, regulatory testing, consumer safety, quality control, and particularly for export to the European Union and other regulated markets.
Some aromatic amines, such as benzidine, 4-aminobiphenyl, and 2-naphthylamine, are classified as Group 1 carcinogens by the International Agency for Research on Cancer (IARC). This means there is strong evidence that they cause cancer in humans. These chemicals can bind to DNA, causing mutations that can lead to cancer.
Determining whether different azo dyes are used together in the same textile product is important because the combined use of some azo dyes can increase total aromatic amine release. Determining whether each azo dye is used alone in a product is critical, particularly for identifying aromatic amine derivatives subject to regulation.
Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, boasts a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the standard "EN ISO 14362-1 Textiles - Methods for the determination of certain aromatic amines derived from azo dyes - Part 1: Determination of the use of certain azo dyes accessible with or without fiber extraction."
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