Overview
EN ISO 21135:2024 (ISO 21135:2024) defines a standardized analytical method for determining the total (solvent-extractable) content of selected bisphenols in chemicals used by the leather tanning industry. The standard covers five target analytes: bisphenol A (BPA), bisphenol AF, bisphenol B, bisphenol F and bisphenol S (BPS). It specifies sample extraction and liquid chromatography (LC)-based instrumental analysis options to identify and quantify these bisphenols in tanning chemicals.
Key topics and technical requirements
- Scope: Quantification of solvent-extractable bisphenols in leather tanning chemicals (BPA, AF, B, F, S).
- Extraction principle: Methanol extraction assisted by an ultrasonic bath (sample preparation details and equipment characteristics specified).
- Instrumentation (LC-based):
- LC coupled to single quadrupole MS, triple quadrupole MS/MS, UV detector (LC‑UV), diode array detector (LC‑DAD), or fluorescence detector (LC‑FLD).
- Note: Bisphenol S cannot be detected by FLD.
- Sample handling: Use of PTFE syringe membrane filters (0.2 µm or 0.45 µm), LC vials and analytical glassware; recommendations for ultra‑pure solvents for LC‑MS/MS.
- Calibration and quantification: Procedures for calculation with and without internal standards; use of mass-labeled internal standards is highly recommended for LC‑MS/MS to mitigate matrix effects.
- Documentation: Method annexes provide chromatographic operating parameters and method precision/reliability data.
Applications and practical value
- Quality control (QC) for chemical suppliers and tanneries to monitor bisphenol residues in tanning agents and intermediates.
- Regulatory compliance and risk assessment where bisphenols are restricted or classified (e.g., reproductive toxicity, endocrine disruption concerns noted in regulatory guidance).
- Product safety testing to reduce bisphenol contamination in leather goods and to support supplier declarations.
- Method transfer and laboratory validation: Laboratories can validate the method for other bisphenols beyond the five listed, provided proper validation is performed.
Who should use this standard
- Analytical testing laboratories performing leather chemical analyses.
- Leather manufacturers and chemical suppliers conducting in‑house QC.
- Regulatory bodies and conformity assessment organizations evaluating chemical safety in leather production.
- R&D teams optimizing tanning formulations to minimize bisphenol residues.
Related standards
- Published under ISO/IULTCS in collaboration with CEN/TC 289 (Leather). Users should consult other ISO/IULTCS and CEN leather testing standards and national transpositions for complementary methods, quality systems and legal requirements.
Adopting EN ISO 21135:2024 helps laboratories and industry stakeholders implement a harmonized, LC‑based procedure for accurate detection and quantification of bisphenols in leather tanning chemicals.
