Overview
EN ISO 23168:2020 - Paints and varnishes: Determination of water content - Gas‑chromatographic method (ISO 23168:2019) specifies a laboratory procedure to determine the water mass fraction in water‑borne coatings and their raw materials using gas chromatography (GC). The method uses an internal standard, dilution with organic solvent, chromatographic separation and detection (thermoconductivity detector) to quantify water. The preferred working range is 15% to 90% water mass fraction, but the procedure can be applied outside this range.
Key topics and technical requirements
- Principle: Internal standardisation, dilution, GC separation of water, detection by a thermoconductivity detector (TCD) and quantification from peak areas.
- Apparatus: Requirements for the gas chromatograph, variable‑temperature injection block with a sample splitter, oven capable of 40–300 °C, capillary column, silanized glass wool in the splitter to retain non‑volatile constituents, suitable injection syringe, carrier gas and filters.
- Sample handling: Guidance on sampling, sample vials, molecular sieves, and bottle‑top dispensers to avoid contamination and water loss.
- Reagents and calibration: Use of anhydrous internal standard, appropriate dilution solvent, and consideration of water content in the solvent; calibration procedures and quantitative determination steps are specified.
- Performance and quality: The standard includes requirements for data processing, precision assessment (repeatability and reproducibility limits), test reporting and example GC conditions (informative annexes).
Applications and practical value
- Quality control of water-borne paints and varnishes during manufacture, formulation and incoming raw‑material inspection.
- R&D and formulation laboratories assessing moisture content for process control, stability studies and troubleshooting (e.g., film formation issues, storage stability).
- Regulatory compliance and specification verification where documented, reproducible water measurements are required.
- Complementary or alternative method to Karl Fischer titration for systems where GC is advantageous (e.g., when volatile organics are present) - users should consider method applicability and intercomparisons.
Who should use this standard
- Coatings manufacturers, raw‑material suppliers and contract labs.
- Analytical chemists, QC managers and laboratory technicians in the paints & varnishes industry.
- Test houses and certification bodies performing standardized moisture determinations.
Related standards
- ISO 760 - Determination of water (Karl Fischer method)
- ISO 1513 - Sample preparation for paints and varnishes
- ISO 3696 - Water for analytical laboratory use
- ISO 4618 - Terms and definitions for paints and varnishes
- ISO 15528 - Sampling of paints and raw materials
Keywords: EN ISO 23168:2020, gas chromatography, water content determination, paints and varnishes, water‑borne coatings, thermoconductivity detector, internal standard, QC method.