ISO 22195-4:2021

Overview

ISO 22195-4:2021 is an international standard developed by ISO that specifies a precise test method for identifying catechu as an index ingredient in coloured textiles. Catechu, a natural dye extract from the heartwood of the Acacia catechu tree, imparts a characteristic brown colour and can be applied on both natural and man-made fibres. This standard focuses on detecting catechin, the key chemical marker in catechu, through high performance liquid chromatography (HPLC) techniques.

Understanding and verifying the presence of natural colourants like catechu in textiles is crucial for authenticity, quality control, and supporting environmental claims related to sustainable dyeing processes. ISO 22195-4:2021 provides a validated analytical approach to identify catechu-based dyes, contributing to transparency and standardization in the textile industry.

Key Topics

• Scope: Identification of catechu dye in coloured textiles made from natural or synthetic fibres.
• Test Principle: Extraction of the dyed sample followed by chemical identification of catechin, the chromophoric compound in catechu, using HPLC with photo diode array detection.
• Reagents and Apparatus:
  • Use of high-purity reagents such as acetonitrile, dimethylformamide (DMF), and trifluoroacetic acid.
  • Equipment includes analytical balance, ultrasonic water bath, membrane filter, and HPLC system with PDA detector.
• Procedure:
  • Sample preparation involves cutting fabric, solvent extraction in DMF, and filtration of the extract.
  • HPLC analysis for retention time and absorption spectra matching catechin standard.
• Test Report: Must include sample identification, chromatographic conditions, presence and quantity of catechin, and adherence to the methodology.
• Chromatographic Conditions:
  • C-18 column with specific mobile phases (water with trifluoroacetic acid and acetonitrile).
  • Detection wavelength set at 300 nm.
  • Flow rate typically 0.8 ml/min with an 18-minute run time.

Applications

• Textile Authentication: Confirmation of textile dye origins, distinguishing catechu-based natural dyes from synthetic dyes or other natural colourants.
• Environmental Verification: Supporting environmental claims by accurately identifying natural dyes used in textile products, critical for green labeling and sustainability certifications.
• Quality Control: Ensuring consistency and authenticity in fabric production lines incorporating catechu as a natural dye.
• Research and Development: Facilitates studies on natural dyes, their chemical composition, and impacts on fibre types.
• Heritage Textile Analysis: Enables examination of historical textiles, artworks, manuscripts, and crafts dyed with traditional natural substances.

Related Standards

• ISO 3696 - Water for analytical laboratory use - Specification and test methods, providing guidelines for purity of water used in chemical analysis within this method.
• ISO 22195 Series - This part 4 standard is part of the broader ISO 22195 series, which covers determination of index ingredients from coloured textiles using various natural colourants.
• ISO/IEC Directives - Principles and rules for the development and maintenance of international standards, ensuring globally consistent and reliable procedures.
• Complementary standards on dye testing methods, textile fibre identification, and environmental impact assessments may support the use and interpretation of this method.

Keywords: ISO 22195-4:2021, catechu dye, natural colourant identification, textile dye testing, catechin detection, HPLC textile analysis, natural dyes verification, sustainable textiles, coloured fabric testing, textile standards, analytical method ISO, natural dye chromatography.