Determination of Volatile Organic Compounds in Water-based Paints and Varnishes Using Gas Chromatography

Significance of the Topic

The release of volatile organic compounds (VOCs) during application and drying of paints poses health and environmental risks. Water-based paints with low VOC content have expanded in market share, necessitating reliable analytical methods to verify compliance with regulations. Rapid, accurate determination of VOCs in these formulations supports quality control, regulatory adherence and safer indoor environments.

Objectives and Study Overview

This work aimed to develop and validate a fast, robust gas chromatography (GC) method for quantifying thirty common VOCs in water-based paints and varnishes. The method follows the Chinese standard GB 18582-2008, adapts it for accelerated analysis and demonstrates its application to commercial indoor and outdoor paint samples.

Instrumentation

Gas chromatograph: Shimadzu GC-2025 with AOC-20i auto-injector
Column: J&W DB-1701, 30 m × 0.25 mm × 0.25 µm film thickness
Detector: Flame ionization detector (FID-2010)
Carrier gas: Helium (99.9997 %) at constant linear velocity mode (37.5 cm/s)
Temperature program: Initial 35 °C (1 min), ramped in steps to 240 °C over 10.5 min total run time

Methodology

Stock solutions of thirty VOCs, two internal standards (dimethyl glycol, dimethyl diglycol) and a boiling point marker (diethyl adipate) were prepared in acetonitrile. Paint samples (1 g) were spiked with internal standards, sonicated, centrifuged, filtered and diluted to 10 mL with acetonitrile. A one-point internal standard calibration was applied, requiring prior estimation of VOC concentration in the sample. Compounds eluting after the boiling point marker (>251 °C) were excluded as non-VOCs per GB 18582-2008.

Main Results and Discussion

The optimized GC method achieved baseline separation of 35 peaks, including thirty VOCs, two internal standards and the boiling point marker in 10.5 minutes. Repeatability (%RSD, n=5) was below 0.5 % at 300 mg/L and below 2 % at 30 mg/L for all detectable compounds. Xylenes were quantified as a total, merging m/p-isomers and o-isomer peaks. Two commercial water-based paints were analyzed: an indoor formulation with total VOC content of 32.8 g/L and an outdoor coating with 50.2 g/L, both within the 120 g/L regulatory limit. Unknown peaks eluting before the boiling point marker were quantified using assumed response factors and contributed minor amounts.

Benefits and Practical Applications

• Fast analysis (10.5 min) enhances laboratory throughput.
• High precision supports reliable quality control.
• One-point calibration simplifies routine testing.
• Compliance verification for regulatory standards and product labeling.

Future Trends and Potential Applications

Further development may include coupling to mass spectrometry for enhanced identification of unknowns, automation of sample preparation workflows, application to other low-VOC matrices (e.g., adhesives, sealants) and miniaturized instrumentation for field screening. Integration with data analytics could improve process control in industrial paint manufacturing.

Conclusion

A rapid, precise GC-FID method was established for quantifying thirty VOCs in water-based paints. The approach meets regulatory requirements, delivers excellent repeatability and is suitable for routine QC laboratories. Its simplicity and speed make it a valuable tool for enforcing VOC limits and ensuring product safety.

References

• G. Wieslander, D. Norbäck, E. Björnsson, Int. Arch. Occup. Environ. Health 1997, 69, 115–124.
• US EPA, An Introduction to Indoor Air Quality, 2014.
• PaintQuality.com, Water-Based vs. Solvent-Based Paints, 2014.
• GB 18582-2008, Indoor Decorating and Refurnishing Materials – Limit of Harmful Substances of Interior Architectural Coatings.
• ISO 11890-2:2013, Paints and Varnishes – Determination of Volatile Organic Compound (VOC) Content – Part 2: Gas-Chromatographic Method.