DIN EN ISO 17234-2:2011-06

This part of ISO 17234 is supplementary to ISO 17234-1 and describes a special procedure to detect the use of certain azo colorants in commodities, which can release 4-aminoazobenzene. The procedure also detects 4-aminoazobenzene (Solvent Yellow 1) which is already available as free amine in commodities without reducing pretreatment. Azo colorants that are able to form 4-aminoazobenzene generate, under the conditions of ISO 17234-1, the amines aniline and 1,4-phenylenediamine. The presence of these 4-aminoazobenzene colorants cannot be reliably ascertained without additional information (for example, the chemical structure of the colorant used) or without a special procedure. The use of certain azo colorants, which may release, by reductive cleavage of their azo group(s), one or more of the other aromatic amines listed in Annex XVII of Regulation (EC) No. 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), except 4-aminoazobenzene, cannot be determined quantitatively with this method. Certain azo colorants may release by reductive cleavage of their azo group(s), 4-aminoazobenzene, which is proscribed under Annex XVII of Regulation (EC) No. 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). If 4-aminoazobenzene is detected by one chromatographic method, confirmation shall be made using one or more alternative methods. Amine quantification is performed by HPLC/DAD. After degreasing, the leather sample is treated with sodium dithionite in an alkaline solution at 40 °C in a closed vessel. 4-Aminoazobenzene, which is released in the process, is transferred to a tert-butyl methyl ether phase by means of liquid/liquid extraction. An aliquot of the tert-butyl methyl ether phase is used for analysis. The detection and determination of 4-aminoazobenzene is performed using high-performance liquid chromatography (HPLC) with a diode array detector (DAD) or mass selective detector (HPLC/MS), capillary gas chromatography with a mass-selective detector (GC/MS) or capillary electrophoresis with a diode array detector (CE/DAD), or qualitatively with thin-layer chromatography (TLC, HPTLC). This document (EN ISO 17234-2:2011) has been prepared by Technical Committee CEN/TC 289 "Leather", the secretariat of which is held by UNI (Italy), in collaboration with the "International Union of Leather Technologists and Chemists Societies". The responsible German committee is NA 062-05-52 AA "Chemische Prüfverfahren für Leder" ("Chemical test methods of leather") of the Materials Testing Standards Committee (NMP) at DIN.