Overview
EN ISO 1833-15:2019 - Textiles: Quantitative chemical analysis, Part 15 - specifies a chemical method for determining the composition of textiles made from mixtures of jute and certain animal fibres (hair and/or wool). The method is based on measuring the sample’s nitrogen content (Kjeldahl principle) after removal of non‑fibrous matter, and calculating the proportion of each component from known nitrogen contents. This part of the ISO 1833 series is a standalone procedure and is not applicable to products or finishes that contain nitrogen‑based dyestuffs or treatments.
Key topics and requirements
- Scope: Determination of the proportion of jute and animal fibres in blended textiles (jute + hair and/or wool).
- Analytical principle: Nitrogen determination (Kjeldahl digestion, distillation and titration) and conversion of nitrogen percentage to fibre proportions.
- Pre‑treatment: Removal of non‑fibrous matter via solvent extraction (Soxhlet with toluene/methanol) and repeated water extraction, followed by drying - to ensure accurate nitrogen measurement.
- Apparatus & reagents: Kjeldahl digestion and distillation apparatus, Soxhlet extractor, sulfuric acid, potassium sulfate, selenium catalyst, sodium hydroxide, boric acid and standard titrant (sulfuric acid). Reagent and apparatus requirements follow good laboratory and ISO 1833‑1 practice.
- Test procedure: Sampling per ISO 5089, specimen weighing, Kjeldahl digestion, distillation into boric acid, titration and blank correction. Results are calculated as percentage nitrogen and converted to component proportions using the known nitrogen contents of jute and the animal‑fibre component.
- Limitations & safety: Not suitable when dye or finishing agents contain nitrogen. Toxic solvents (toluene, methanol) and corrosive reagents require appropriate safety controls. Precision and calculation details are provided in the standard.
Applications and users
- Who uses it: Textile testing laboratories, manufacturers of jute‑blend fabrics, quality control and R&D teams, import/export compliance bodies, and standards organizations.
- Practical uses:
- Verifying declared fibre composition for quality control and labeling compliance.
- Resolving disputes over product composition in commercial transactions.
- Supporting product development where precise fibre ratio (jute vs. animal fibres) affects performance, dyeing or mechanical properties.
- Regulatory and certification testing for natural fibre textiles.
Related standards
- ISO 1833‑1 - General principles of quantitative chemical analysis for textiles (note: this part differs in principle from ISO 1833‑1’s selective‑solubility methods).
- ISO 5089 - Preparation of laboratory test samples and test specimens for chemical testing.
Keywords: EN ISO 1833-15:2019, jute, nitrogen content, Kjeldahl, quantitative chemical analysis, textiles, Soxhlet extraction, wool, hair, ISO 1833 series.
