ISO 22195-5:2021

Overview

ISO 22195-5:2021 sets the international standard for identifying the index ingredient chemical-laccic acid C-within coloured textiles dyed using lac dye. This test method applies to both natural fibers and man-made fibers coloured with lac, a natural resinous secretion from lac insects (Kerria lacca). The standard is part 5 of the ISO 22195 series focusing on the determination of natural colourants in textiles.

Accurate identification of lac dye is essential for verifying natural dye claims, which are increasingly important for environmental sustainability in textile production. This method uses chromatographic analysis (HPLC-PDA) to extract and detect laccaic acid C, the key chemical marker of lac dye.

Key Topics

• Scope and Application
  Targets textiles coloured with lac dye on both natural and synthetic fibers. Establishes a reproducible procedure to identify the index ingredient chemical from coloured fabrics.

• Principle
  Lac dye contains a unique chromophore-laccaic acid C-that can be chemically extracted from textiles and detected by high performance liquid chromatography using a photodiode array detector (HPLC-PDA).

• Reagents and Apparatus
  Requires analytical-grade solvents such as acetonitrile, dimethylformamide (DMF), and trifluoroacetic acid. Essential equipment includes an ultrasonic bath for extraction, membrane filters, and HPLC-PDA system.

• Test Procedure

  1. Sample preparation by cutting textile into small pieces.
  2. Extraction of the lac dye using DMF in an ultrasonic bath.
  3. Filtration of the extract and analysis by HPLC-PDA, comparing retention time and absorbance with a laccaic acid C standard.
  4. Qualification based on chromatographic matching confirms lac presence.

• Test Reporting
  Comprehensive test report must include references, sample details, chromatographic conditions, results, deviations from procedure, and test date.

Applications

• Textile Quality Control
  Enables textile manufacturers and laboratories to verify natural dye usage, particularly lac dye, guaranteeing authenticity.

• Environmental Verification
  Supports environmental claims by confirming the use of natural lac dyes, which are valued for lower ecological impact compared to synthetic dyes.

• Cultural Heritage and Conservation
  Assists in scientific examinations of historical textiles, artworks, and manuscripts to identify natural lac-based colorants.

• Regulatory Compliance
  Provides standardized methods for regulatory agencies and certification bodies assessing natural dye content in textile products.

Related Standards

• ISO 22195 Series
  Covers the determination of index ingredients from various coloured textiles with natural dyes.

• ISO 3696: Water for analytical laboratory use
  Specifies quality requirements for water used in analysis, referenced for reagent preparation.

• ISO/IEC Directives Part 1 & 2
  Governs the editorial rules and development processes for ISO standards, ensuring consistency and clarity.

By implementing ISO 22195-5:2021, textile professionals can reliably detect lac dye presence using scientific extraction and chromatographic analysis methods. This enhances product transparency, supports sustainable textile practices, and preserves the integrity of textiles dyed with traditional natural colorants.