Analysis of Solvents in Industrial Atmospheres by Capillary GC

Significance of the Topic

Industrial solvents are ubiquitous in manufacturing, chemical processing, and maintenance operations. Inhalation of these volatile compounds can pose significant health risks to workers, leading regulatory bodies such as OSHA to mandate routine monitoring of solvent concentrations in workplace air. Reliable chromatographic methods are essential for identifying and quantifying complex solvent mixtures to ensure compliance with exposure limits and to maintain a safe working environment.

Objectives and Study Overview

This application note evaluates the complementary use of two capillary gas chromatography columns—with differing stationary phase polarities—to achieve comprehensive separation and identification of industrial solvents collected on adsorbent tubes. The study compares the performance of a highly polar SUPELCOWAX 10 column against a nonpolar PTE-5 column, demonstrating how combined retention information enhances analytical confidence in complex samples.

Methodology and Instrumentation

Samples of mixed industrial solvents were collected on adsorbent tubes, thermally desorbed, and split between two GC systems, each equipped with a flame ionization detector. The SUPELCOWAX 10 column (30 m × 0.53 mm ID, 1.0 μm film) exploits polarity differences, while the PTE-5 column (30 m × 0.32 mm ID, 1.0 μm film) separates primarily by boiling point. Both columns used helium carrier gas and temperature programming from 40 °C to 200 °C at 5 °C/min for SUPELCOWAX 10 (5 min initial hold) and 40 °C to 130 °C at 4 °C/min for PTE-5.

Main Results and Discussion

The SUPELCOWAX 10 column achieved baseline resolution of o-, p-, and m-xylenes and near-baseline separation of p- and m-cresols, highlighting its strong retention of polar compounds. In contrast, the PTE-5 column separated compounds roughly in boiling-point order, with nonpolar species eluting earlier. Retention time shifts between the two columns provide an additional identification parameter. For example, methanol exhibited a significant shift due to its high polarity on SUPELCOWAX 10, improving peak symmetry compared to PTE-5. A comparative elution table summarized the order and retention behavior of 50 common industrial solvents on both phases.

Benefits and Practical Applications

• Enhanced Identification: Dual-column analysis reduces ambiguities arising from coelutions by providing orthogonal retention data.
• Improved Resolution of Polar Analytes: The polar phase delivers sharper, symmetric peaks for alcohols and other polar solvents.
• Regulatory Compliance: Accurate quantitation supports adherence to occupational exposure limits.
• Flexible Workflow: Analysts can perform simultaneous dual-detector analysis or confirm suspect peaks with a second column as needed.

Future Trends and Opportunities

Advances in multidimensional GC (GC×GC) and coupling with mass spectrometry will further increase separation power for complex solvent mixtures. Development of novel stationary phases tailored for specific classes of volatile organic compounds will improve selectivity. Integration of automated sampling, data processing with machine learning–based peak identification, and portable GC instruments will enable on-site real-time monitoring, enhancing industrial hygiene practices.

Conclusion

The combined use of a polar SUPELCOWAX 10 column and a nonpolar PTE-5 column offers a robust strategy for the comprehensive analysis of industrial solvents in workplace atmospheres. By leveraging complementary separation mechanisms, analysts can achieve reliable identification and quantitation across a broad range of compounds, ensuring worker safety and regulatory compliance.

Reference

Sigma-Aldrich Co. Application Note: “Analysis of Solvents in Industrial Atmospheres by Capillary GC.”