ISO 5773:2023

Overview

ISO 5773:2023 - Textiles - Determination of components in flax fibres - defines standardized laboratory methods to quantify the main chemical components of flax fibres. The standard covers test procedures for cellulose, hemicellulose, lignin, pectin, fat and wax content in flax and serves as a reference for testing other bast fibres. Methods combine physical/chemical extraction with gravimetric analysis, titration and spectrophotometry.

Key topics and technical requirements

• Scope: Quantitative analysis of individual fibre components (cellulose, hemicellulose, lignin, pectin, fats and waxes); applicable to flax and useful as a reference for other bast fibres.
• Principle: Sequential physical and chemical treatments to isolate components followed by gravimetric and colorimetric/spectrophotometric determination.
• Reagents and purities: Standard lists include sodium hydroxide, sulfuric and hydrochloric acids, ammonium oxalate, anthrone, carbazole, DNS reagent, glucose and galacturonic acid standards, acetone, ethanol, barium chloride, etc., with specified purity requirements.
• Apparatus: Soxhlet extraction apparatus, spectrophotometer (200–800 nm, 1 cm cuvette), analytical balances (0.0001 g resolution), ventilated oven, oil bath, fritted filter (P40), volumetric glassware, thermostatic water bath.
• Test procedure detail: Preparation of multiple standard solutions (galacturonic acid, glucose, DNS chromogenic solution, anthrone in sulfuric acid), sampling and specimen preparation (drying to constant mass), extraction (e.g., acetone Soxhlet for fat and wax), hydrolysis and spectrophotometric assays for polysaccharides and lignin, and calculation/reporting requirements.
• Measurement methods: Gravimetric extraction, titration and ultraviolet/visible spectrophotometry; standard curves for glucose and galacturonic acid are specified.

Applications and users

ISO 5773:2023 is designed for:

• Textile testing laboratories performing fibre composition analysis and quality control.
• Fibre producers and processors (flax growers, retting/process engineers) monitoring biochemical composition.
• Research institutions studying natural fibre properties, biodegradability and fiber-to-textile conversion.
• Manufacturers evaluating raw material suitability for composites, yarns and technical textiles where cellulose/hemicellulose/lignin ratios affect performance.

Practical benefits include consistent, comparable test results across laboratories, improved quality control, and support for material selection in textile and composite applications.

Related standards

• ISO 1130 - Sampling methods for textile fibres (referenced for representative sampling)
• ISO 3696 - Water for analytical laboratory use (reagent water quality)
• ISO 4793 - Laboratory fritted filters (porosity classification)

ISO 5773:2023 provides a complete, reproducible framework for chemical component analysis of flax fibres and is essential for laboratories and industry stakeholders requiring reliable, standardized fibre composition data.