Overview
ISO 22518:2019 specifies a validated gas‑chromatographic method for the quantitative determination of solvents in water‑thinnable paints and varnishes, binder solutions, emulsions and dispersions. The method resolves single solvent components down to 0.02% (mass fraction) with the precision given in the standard. Note: ISO 22518:2019 is not intended for total VOC or SVOC content determination (see ISO 11890‑2 for VOC/SVOC methods).
Key topics and technical requirements
- Principle: Separation of solvent components by gas chromatography (GC) followed by quantification using an internal standard and peak‑area integration.
- Instrumentation:
- Capillary GC suitable for fused silica/glass columns; example column: 50 m × 0.2 mm i.d., film ~0.2 µm (stationary phase chosen for separation).
- Injection systems: hot injection, cold injection (temperature programmable to 300 °C), or automatic injector to improve precision. Choose cold injection when thermal decomposition or interfering products occur.
- Detector: Flame Ionization Detector (FID) operable up to 300 °C; detector temperature must be at least 10 K above maximum oven temperature. Mass spectrometer or FT‑IR may be coupled for identification if required.
- Syringes: 0.5–10 µL capacity with 0.1 µL graduations.
- Chromatographic performance:
- Peak resolution R ≥ 1.5 for components to be separated and quantified.
- Integration and data‑acquisition parameters must be consistent between calibration and sample analysis.
- Reagents and gases:
- Carrier gas: dry O2‑free He, N2 or H2 (≥ 99.996%).
- Detector gases: H2 (≥ 99.999%) and synthetic air free of organics.
- Internal standards: e.g., isobutanol or diethylene glycol dimethyl ether; must be inert and thermally stable.
- Diluents: methanol or tetrahydrofuran of ≥ 99% purity (or known purity).
- Sampling, calibration and reporting: Follow ISO 15528 for sampling; calibration uses high‑purity solvent standards; results expressed as percentage mass fraction. Precision details and test report requirements are specified in the standard.
Applications and users
ISO 22518:2019 is used by:
- Quality control and analytical chemistry laboratories in paint, varnish and coatings manufacturing.
- R&D and formulation teams for solvent profiling in water‑thinnable coatings.
- Third‑party and contract testing labs performing solvent identification and quantification in binder solutions, emulsions and dispersions.
- Regulatory or compliance testing where component‑level solvent analysis (not VOC totals) is required.
Practical benefits include reliable solvent quantification, guidance on instrument configuration (hot vs cold injection), and standardized reporting for product control and comparative studies.
Related standards
- ISO 11890‑2 - Determination of VOC and SVOC content (see for total VOC/SVOC methods)
- ISO 15528 - Sampling for paints and varnishes
- ISO 4618 - Terms and definitions for paints and varnishes
Keywords: ISO 22518:2019, gas chromatographic method, solvent determination, water‑thinnable paints, FID detector, capillary column, internal standard, paint testing, solvent analysis.