Overview
ISO 1833-15:2019 specifies a quantitative chemical analysis method for determining the composition of textiles that are mixtures of jute and certain animal fibres (wool and/or hair). The method calculates the proportion of each component by determining the total nitrogen content (Kjeldahl principle) after removal of non-fibrous matter. This part of ISO 1833 is a complete standalone procedure because its principle (nitrogen determination) differs from the selective-solubility methods in ISO 1833‑1. Note: the method is not applicable to products containing nitrogenous dyestuffs or nitrogen-containing finishes.
Key Topics and Requirements
- Scope and applicability
- Mixtures of jute with wool and/or hair; animal-fibre component may be hair, wool, or their blend.
- Excludes textiles with nitrogen-containing dyes or finishes.
- Sample preparation
- Representative reduced laboratory sample per ISO 5089.
- Solvent extraction in a Soxhlet (toluene:methanol 1:3) and aqueous extraction to remove non-fibrous matter.
- Drying to constant mass before analysis.
- Analytical principle
- Kjeldahl mineralization (H2SO4 with potassium sulfate and selenium dioxide) to convert organic nitrogen to ammonium sulfate.
- Alkaline distillation and trapping in boric acid, followed by titration with standardized sulfuric acid.
- Use of Kjeldahl distillation apparatus and titrator (accuracy ~0.05 ml).
- Calculations
- Percent nitrogen in the dehydrated test portion computed from titration volumes and acid concentration.
- Conversion to fibre composition using prescribed nitrogen contents: jute = 0.22% N, animal fibres = 16.2% N, and the provided formula (ISO 1833-15:2019) to calculate percent animal fibre.
- Reagents and safety
- Analytical-grade reagents: toluene, methanol, sulfuric acid, potassium sulfate, selenium dioxide, NaOH, boric acid.
- Safety precautions for toxic solvents and strong acids required.
Applications and Users
- Textile testing laboratories performing composition analysis for incoming materials, incoming quality control, and product verification.
- Manufacturers of blended jute products who need accurate blend ratios for labelling, process control, and quality assurance.
- Standards and conformity bodies verifying compliance with product specifications or regulations.
- Industry R&D and forensic textile analysts requiring reliable quantitative composition data where selective-solubility methods are unsuitable.
Keywords: ISO 1833-15:2019, textiles quantitative chemical analysis, jute blends, nitrogen determination, Kjeldahl method, Soxhlet extraction, textile composition analysis.
Related Standards
- ISO 1833-1 - General principles of quantitative chemical analysis of textiles (selective solubility methods).
- ISO 5089 - Preparation of reduced laboratory samples and test specimens for chemical tests.
Open preview (PDF)Textiles — Quantitative chemical analysis — Part 15: Mixtures of jute with certain animal fibres (method by determining nitrogen content)