Overview
EN ISO 17234-2:2011 (ISO 17234-2:2011) specifies a chemical test procedure for the detection and determination of 4‑aminoazobenzene in dyed leathers. This part is supplementary to ISO 17234‑1 and is intended to reveal the use of certain azo colorants (including Solvent Yellow 1) that can release 4‑aminoazobenzene either as a free amine or after reductive cleavage. The standard is published by CEN in collaboration with IULTCS and is directly relevant to regulatory compliance under REACH (EC No. 1907/2006, Annex XVII) where 4‑aminoazobenzene is prohibited.
Key topics and technical requirements
- Scope: Special procedure to detect azo colorants that can form 4‑aminoazobenzene; complementary to ISO 17234‑1.
- Principle: Degrease and reductively cleave samples using sodium dithionite in alkaline medium at (40 ± 2) °C in a closed vessel. Released 4‑aminoazobenzene is extracted into tert‑butyl methyl ether and concentrated for analysis.
- Analytical methods: Identification/determination by HPLC with DAD (preferred for quantification), HPLC‑MS, GC‑MS, CE‑DAD; qualitative confirmation by TLC/HPTLC. Positive findings from one method must be confirmed by an alternative method.
- Sampling and sample prep: Follow ISO 2418 (sampling location) and ISO 4044 (preparation of chemical test samples).
- Reagents and standards: Use analytical‑grade reagents (NaOH, sodium dithionite, solvents), certified 4‑aminoazobenzene standard and appropriate internal standards for GC.
- Safety: 4‑aminoazobenzene is a suspected human carcinogen; strict lab safety and disposal procedures required.
- Reporting & reliability: Includes calibration, system checks and guidance on calculation with/without internal standard and method reliability.
Practical applications and users
This standard is primarily used for:
- Regulatory compliance testing (REACH / Annex XVII) for prohibited aromatic amines.
- Quality control in leather manufacturing and finishing to ensure dyes do not release hazardous amines.
- Independent testing laboratories and third‑party conformity assessment bodies performing chemical safety testing on dyed leathers and leather goods.
- Importers, brand owners and product safety managers verifying supplier compliance and preventing hazardous azo colorant use.
Keywords: EN ISO 17234-2:2011, 4‑aminoazobenzene testing, azo colorants, leather chemical tests, HPLC DAD, GC‑MS, REACH compliance.
Related standards
- ISO 17234‑1 - Determination of certain aromatic amines from azo colorants (complements Part 2)
- 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