Rtx-Wax: A Rugged and Reliable Choice for the Analysis of Glycols in Water

Significance of the Topic

Glycols such as ethylene and propylene glycol are widely used in industrial processes, from deicing fluids to hydraulic fracturing. Accurate detection and quantification of these polar compounds in aqueous matrices are essential for environmental monitoring and quality control in industrial laboratories.

Study Objectives and Overview

This evaluation compared the analytical performance of a Restek Rtx-Wax polyethylene glycol (PEG) column against two competitor PEG columns (Column A and Column B) to determine suitability for direct aqueous injection in the gas chromatographic analysis of glycols.

Methodology

The study assessed three columns (30 m × 0.53 mm i.d. × 1.0 µm) under optimized split injection conditions. Key performance parameters included linearity across 0.5–100 ng on-column, column lifetime under repeated water injections, and column bleed at elevated temperatures.

Instrumentation Used

• Gas chromatograph: Agilent/HP6890 GC with FID detector
• Injection: 1 µL split (50:1 for lifetime tests; 20:1 for bleed studies)
• Carrier gas: Helium at constant flow; FID make-up gas nitrogen; hydrogen and air at 40 mL/min and 450 mL/min respectively
• Oven program: 40 °C hold then ramp to 240–260 °C at 30 °C/min

Main Results and Discussion

• Linearity: Rtx-Wax achieved R² = 0.9999 for both ethylene and propylene glycol from 0.5 to 100 ng, while competitor columns failed to detect low-level standards due to high bleed.
• Lifetime: Rtx-Wax maintained peak symmetry above 0.9 after 600 aqueous injections, with extended tests exceeding 1,600 injections without performance loss; competitor columns were excluded from lifetime testing.
• Bleed: At 240 °C, Rtx-Wax exhibited the lowest baseline bleed, supporting sensitive detection down to 0.5 ng and offering a wider temperature range up to 250 °C.

Benefits and Practical Applications

The Rtx-Wax column’s combination of low bleed, high sensitivity, and robust lifetime under repeated water injections makes it ideal for trace-level glycol analysis in environmental water testing, industrial process monitoring, and quality control laboratories.

Future Trends and Opportunities

• Adoption in high-throughput automated sampling and screening workflows.
• Development of next-generation PEG phases with further enhanced water resistance.
• Application to other polar analytes requiring ultra-low detection limits in aqueous matrices.

Conclusion

The Rtx-Wax PEG column outperforms competing columns in linearity, durability, and bleed characteristics, establishing it as a rugged and reliable solution for glycol analysis in water.

References

• Restek Application Note EVAN2873, Restek Corporation