ISO 17234-2:2011

Overview

ISO 17234-2:2011 - Leather: Chemical tests for the determination of certain azo colorants in dyed leathers - Part 2: Determination of 4‑aminoazobenzene describes a specialised analytical procedure to detect and quantify 4‑aminoazobenzene (Solvent Yellow 1) in leather. Supplementary to ISO 17234‑1, this standard targets azo colorants that can release 4‑aminoazobenzene by reductive cleavage of azo groups and sets out sample preparation, extraction and chromatographic analysis steps for reliable detection and quantification.

Key topics and requirements

• Scope and purpose: Detects free 4‑aminoazobenzene and azo dyes that can generate it under reductive conditions; important for regulatory compliance (REACH Annex XVII).
• Sample preparation: Degreasing (n‑hexane ultrasonic treatment), grinding/sampling per ISO 2418 and ISO 4044, removal of adhesives and separation of colour zones for patchwork leather.
• Reductive cleavage: Treatment with aqueous sodium dithionite in alkaline medium at (40 ± 2) °C for 30 minutes in a gas‑tight vessel to release amines.
• Extraction and concentration: Liquid–liquid extraction into tert‑butyl methyl ether with salting‑out (NaCl); optional concentration by rotary evaporator with precautions to avoid analyte loss.
• Analytical techniques: Detection by HPLC/DAD, HPLC/MS, GC/MS, CE/DAD or TLC/HPTLC; quantification typically by HPLC/DAD or GC/MS (use internal standards for GC/MS).
• Calibration and performance checks: Calibration solutions and recovery checks (phase partition recovery ~95–100%; procedural check recovery ≥60%).
• Safety: 4‑aminoazobenzene is a suspected human carcinogen - follow national safety regulations, MSDS guidance and use PPE (gloves, eyewear, respirator for powders).

Practical applications and users

• Regulatory compliance testing: Laboratories verifying leather products against REACH Annex XVII limits and national chemical restrictions.
• Quality control in tanneries and manufacturers: Screening dyed leathers, footwear, garments and accessories for banned or hazardous azo colorants.
• Third‑party test labs and OEMs: Contract testing, supplier audits and material certification for import/export and retail safety.
• Research and method development: Analytical chemists developing confirmatory workflows using HPLC/DAD, GC/MS or CE/DAD.

Related standards and references

• ISO 17234‑1 - Determination of certain aromatic amines from azo colorants (parent method)
• ISO 2418 - Sampling location for leather tests
• ISO 4044 - Preparation of chemical test samples
• REACH (EC) No. 1907/2006 - Annex XVII restrictions on 4‑aminoazobenzene

Keywords: ISO 17234-2:2011, 4‑aminoazobenzene, leather testing, azo colorants, HPLC/DAD, GC/MS, REACH compliance, chemical tests for dyed leathers.