Overview
ISO 14897:2023 specifies laboratory methods for the determination of water content in polyols used as raw materials for the production of polyurethanes. The standard describes two main approaches based on Karl Fischer titration:
- Method A - a manual amperometric titration (included to clarify Karl Fischer principles), and
- Method B - automated amperometric and coulometric titrations.
The coulometric procedure is an absolute method (no calibration required) and offers improved sensitivity compared with amperometric techniques. The standard is intended for quality control, specification testing and research in polyurethane production.
Key topics and technical requirements
- Measurement principles: Karl Fischer reaction (iodine/sulfur dioxide system) and detection by amperometry or coulometry.
- Method scope: Applicable to a wide range of polyether polyols, including colored polyols where visual end-points are obscured.
- Reagents and purity: Reagent-grade chemicals and grade 3 water (ISO 3696) are required. Recommendations include pyridine-free Karl Fischer reagents and guidance on preparing titration solvents. Typical reagent strength guidance is provided (e.g., ~2.5–3.5 mg H2O/ml for Method A).
- Apparatus and instrumentation: Manual titration vessel, platinum electrodes and depolarization indicator for Method A; commercial autotitrators and appropriate reagent systems for Method B.
- Interferences and sample suitability: Oxides, hydroxides and strong bases produce water-like artifacts (can give falsely high results). Amine-containing polyols can shift pH and require mitigation (e.g., addition of salicylic or benzoic acid).
- Procedure, calibration and calculation: Standardization procedures for amperometric titrants and the note that coulometric titration is absolute (no external titrant standardization).
- Precision, bias and reporting: Sections on method precision, bias and required test report content; interlaboratory study data provided in informative annex.
Applications and users
- Who uses it: Analytical laboratories, polyurethane raw-material manufacturers, QC/QA teams, R&D scientists, and regulatory/compliance units.
- Practical applications:
- Incoming raw-material inspection (polyol batches)
- In-process monitoring to prevent isocyanate consumption by water (avoiding CO2 generation and foam defects)
- Specification testing for product release and supplier qualification
- Research into formulation stability and moisture control
Related standards
Keywords: ISO 14897:2023, polyols, water content, Karl Fischer, coulometric titration, amperometric titration, automated titration, polyurethanes, quality control, laboratory method.
Open preview (PDF)Plastics — Polyols for use in the production of polyurethanes — Determination of water content
