Overview
ISO 23168:2019 - Paints and varnishes - Determination of water content - Gas‑chromatographic method defines a standardized gas‑chromatography (GC) procedure for measuring the water content of water‑borne coating materials and their raw materials. The method uses an internal standard, dilution in a dry organic solvent, chromatographic separation and detection by a thermoconductivity detector (TCD). The preferred working range is a water mass fraction of 15 % to 90 %, although the procedure can be applied outside this range.
Keywords: ISO 23168:2019, paints and varnishes, water content, gas chromatographic method, GC water determination, thermoconductivity detector, TCD.
Key Topics and Requirements
- Principle: Internal standardization, dilution of sample, chromatographic separation of water, TCD detection and quantification from peak areas.
- Scope: Suited for water‑borne coatings and raw materials; preferred range 15–90 % water by mass.
- Apparatus: Requirements for GC system components including variable‑temperature injection block with splitter, oven (40–300 °C), capillary column (bonded porous polymer technology), TCD, injection syringe, inert sample vials, gas filter, analytical balance and bottle‑top dispenser.
- Carrier gas: High‑purity hydrogen (≥99.995 %) or helium recommended; carrier gas must be dried/filtered.
- Reagents: Anhydrous internal standard (e.g., 2‑propanol or n‑propanol cited as suitable), dry dilution solvent (e.g., DMF noted), water meeting ISO 3696, and molecular sieve (2–3 Å) for drying.
- Procedure essentials: Optimize GC conditions for each product; determine dilution solvent water by Karl Fischer titration (ISO 760); calibrate response factor; prepare samples in “ready for use” state per ISO 1513.
- Quality and reporting: Includes calibration, precision (repeatability and reproducibility), and required test report information. Annexes provide example GC conditions and precision information.
Applications and Users
ISO 23168:2019 is intended for:
- Quality control and batch release testing in paint and coatings manufacturing
- Raw‑material acceptance testing (binders, additives, solvents)
- Formulation development and stability studies in R&D labs
- Supplier audits and regulatory compliance checks
- Analytical laboratories performing moisture analysis in high‑water‑content coatings
This method is particularly valuable when Karl Fischer titration is impractical (e.g., complex matrices) or when GC separation offers better specificity.
Related Standards
- ISO 760 - Determination of water - Karl Fischer method
- ISO 1513 - Examination and preparation of test samples
- ISO 3696 - Water for analytical laboratory use
- ISO 4618 - Paints and varnishes - Terms and definitions
- ISO 15528 - Sampling for paints and varnishes
For implementation, users should consult the full ISO 23168:2019 document for complete procedures, calibration details and precision data.
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