Overview
ISO 20418-3:2020 specifies a qualitative and quantitative proteomic procedure to determine the composition of animal hair fibre blends (wool, cashmere, yak, alpaca, camel, angora) using peptide detection by LC‑MS without protein reduction. Part of the ISO 20418 series (first edition 2020), this method combines light‑microscopy pre‑identification with trypsin digestion of mechanically powdered fibres and LC‑MS analysis of species‑specific marker peptides to calculate blending ratios and total fibre composition.
Keywords: ISO 20418-3:2020, LC-MS, peptide detection, proteomic analysis, animal hair fibres, cashmere authentication, textile testing.
Key technical topics and requirements
- Scope and applicability
- Designed for blends containing different animal species (e.g., cashmere + sheep wool + yak). Not applicable where fibres of the same species are blended (e.g., cashmere and mohair).
- Sample preparation
- Representative sampling, degreasing/washing, and mechanical powderization of fibres prior to digestion.
- Enzymatic digestion
- Direct trypsin digestion of powdered fibres to release peptides; the method selects cysteine‑free marker peptides, thereby omitting a traditional protein‑reduction step (faster sample prep).
- LC‑MS analysis
- Peptide separation and detection by liquid chromatography–mass spectrometry (LC‑MS) with appropriate mass range capability (e.g., ~m/z 200–1500).
- Use of selected ion monitoring (SIM) or mass chromatograms for species-specific peptides.
- Quantitation and correction
- Calculation of peak areas for marker peptides, application of correction factors (for species differences) and computation of blending ratios and Bovidae/Camelidae rates.
- Reporting and validation
- Criteria for data validity, documentation of test conditions, and test report content are specified.
Practical applications and users
- Textile and fibre testing laboratories - routine compositional testing and quality control of animal‑fibre products.
- Manufacturers and brands - verification of raw material claims (e.g., cashmere content) and prevention of mislabeling or adulteration.
- Regulatory bodies and customs - enforcement of labeling laws and import/export verification.
- Forensic and research labs - authentication of heritage textiles or research on fibre processing effects.
- Advantages include robust performance on processed samples, quantitative capability for blending ratios, and faster sample preparation by avoiding reduction steps.
Related standards (if applicable)
- ISO 20418-1 (related LC‑MS procedure with protein reduction)
- ISO 1833 (all parts) - quantitative chemical analysis of non‑animal fibres
- ISO/TR 11827 - microscopical morphological identification
- ISO 17751 (all parts) - microscopical quantitative analysis of animal fibres
- ISO 3696, ISO 1833-1 - referenced for reagents and sampling principles
This standard is essential for accurate, reproducible proteomic analysis of animal hair fibres and supports reliable textile authentication and compositional testing.