ISO 20418-2:2018

Overview

ISO 20418-2:2018 specifies a qualitative and quantitative proteomic procedure for determining the composition of animal hair fibre blends using MALDI‑TOF MS peptide detection. Designed for textile testing laboratories and quality control, the method complements microscopic and chemical textile standards to deliver objective species identification and percentage composition of blends (e.g., wool, cashmere, yak). The procedure is intended for animal hair fibres only; non‑animal fibres are measured by the ISO 1833 series and combined with MALDI results to give total fabric composition.

Key topics and technical requirements

• Analytical principle: Extraction of keratin proteins from hair, partial purification by SDS‑PAGE, enzymatic digestion (trypsin) and peptide profiling by MALDI‑TOF mass spectrometry. Species-specific peptide markers (m/z peaks) are used for identification and quantification.
• Sample workflow:
  • Preliminary fibre identification by light microscopy (per ISO/TR 11827).
  • Protein extraction with SDS/DTT/phosphate buffer.
  • Partial purification (mini‑SDS‑PAGE) and in‑gel trypsin digestion.
  • MALDI‑TOF MS analysis of tryptic peptides and calculation of species percentages via calibration curves.
• Reagents and consumables: SDS, dithiothreitol (DTT), iodoacetamide, sequencing‑grade trypsin, ammonium bicarbonate, CYMAL‑5 detergent, CHCA matrix and high‑purity water (ISO 3696).
• Apparatus: Ball mill or grinder, electrophoresis system, MALDI target and TOF mass spectrometer, standard lab pipettes and block baths.
• Limitations and scope: Not applicable when fibres from the same animal species (e.g., cashmere and mohair both goat-derived) co‑exist in a blend - such cases require microscopical quantification methods (e.g., ISO 17751 series).
• Quality and validation: Clauses cover calibration curves, calculation methods for binary and ternary mixtures, precision, interlaboratory trials and recommended test reporting.

Applications and users

• Textile testing and certification laboratories performing species identification and composition analysis.
• Quality assurance teams in wool and specialty animal-fibre supply chains (cashmere, yak, goat, sheep).
• Manufacturers and importers verifying label claims and blend percentages.
• Standardization bodies and researchers developing proteomic fibre analysis protocols.

Related standards

• ISO 20418 series (other parts)
• ISO/TR 11827 (microscopy identification)
• ISO 1833 (chemical analysis of non‑animal fibres)
• ISO 17751 series (microscopical quantification methods)
• ISO 3696 (water for laboratory use)

Keywords: ISO 20418-2:2018, MALDI‑TOF MS, proteomic analysis, animal hair fibres, peptide detection, textiles, SDS‑PAGE, trypsin digestion, calibration curve, fibre composition.