Overview
ISO 21437:2020 specifies an analytical method for determining the carbohydrate composition of wood pulps. The standard quantifies the five principal neutral monosaccharides - arabinose, galactose, glucose, mannose and xylose - in pulp samples, with detection down to 1 mg/g oven‑dry pulp. The procedure is based on a two‑step sulfuric acid hydrolysis followed by chromatographic determination of the released monosaccharides.
Key Topics and Requirements
- Scope: Measurement of individual anhydrous monosaccharides in wood pulp (mg/g oven‑dry pulp).
- Principle: Two‑step acid hydrolysis (72% H2SO4 followed by elevated‑temperature treatment) to depolymerize polysaccharides, then chromatographic analysis.
- Analytical methods:
- Ion chromatography (IC) with pulsed amperometric detection (HPAEC‑PAD) for direct monosaccharide analysis.
- Gas chromatography (GC‑FID) after reduction and acetylation to form alditol acetates.
- HPLC methods may be used if validated against ISO 21437 results.
- Sample preparation:
- Representative sampling and grinding.
- Acetone extraction recommended for groundwood / high‑yield pulps to remove resins (ISO 14453).
- Determination of dry matter per ISO 638; testing in duplicate.
- Quality control:
- Use of an internal standard (e.g., 2‑deoxy‑galactose) to validate recovery.
- Calibration with monosaccharide standards and inclusion of precision data (Annex A).
- Apparatus: grinder, filtration setup, water baths, autoclave (120 ±3 °C), IC or GC systems as applicable.
- Reporting: Results expressed in mg monosaccharide per g oven‑dry pulp; include method details, internal standard, and any deviations.
Applications
- Pulp and paper quality control: Monitor polysaccharide composition for product specification and consistency.
- Process optimization: Evaluate effects of pulping and bleaching on carbohydrate content and pulp yields.
- Raw material characterization: Differentiate softwood vs. hardwood or recycled raw materials by monosaccharide profile.
- Research & development: Support studies on biomass composition, enzymatic treatments, or downstream biorefining.
- Regulatory / certification: Provide standardized, comparable carbohydrate data for product claims or certification schemes.
Who uses this standard
- Analytical laboratories in the pulp and paper industry
- Mill process control and R&D teams
- Contract testing labs and certification bodies
- Academic researchers working on wood chemistry and biomass valorization
Related Standards
- ISO 638 - Dry matter content (oven‑drying)
- ISO 7213 - Sampling of pulps
- ISO 14453 - Acetone‑soluble matter (resin extraction)
- ISO 21436 - Lignin determination (linked to hydrolysis residues)
Keywords: ISO 21437, carbohydrate composition, wood pulp analysis, monosaccharides, sulfuric acid hydrolysis, ion chromatography, gas chromatography, pulp testing, HPAEC‑PAD, GC‑FID.
