New high temperature PEG GC column with ultra-low bleed level

Importance of the Topic

Polyethylene glycol (PEG)-based WAX columns are essential for analyzing polar compounds in flavor, fragrance and industrial quality control. However, conventional WAX phases are limited to ~250–260°C, suffer from high bleed, reduced sensitivity and limited lifespan. Developing a high-temperature PEG phase with low bleed and extended upper temperature limit can unlock advanced GC and GC×GC workflows with enhanced detection and robustness.

Objectives and Study Overview

This work introduces a novel High-Temperature WAX (HT-WAX) capillary column designed to operate up to 280–290°C with ultra-low bleed and improved inertness. The goals were:

• Assess bleed behavior across a range of maximum temperatures after standard conditioning
• Evaluate column inertness using stringent test probes (modified Grob and DB-WAX UI mixes)
• Compare HT-WAX performance against existing commercial WAX columns
• Demonstrate applicability in GC/MS and GC×GC configurations

Methodology and Instrumentation

The evaluation included bleed measurements at 250–290°C after 11 h conditioning. Inertness was probed with:

• DB-WAX UI test mix (including ketones, acids and alcohols at ng levels)
• Modified Grob test mix (phenolic derivatives, FAMEs and amines at ~2.5–5 ng)

Columns were 30 m × 0.25 mm id × 0.25 μm film. GC setups involved:

• FID detection at 260°C for bleed/inertness tests
• 5977B High Efficiency Source GC/MSD for phenol mix analysis in full scan mode (35–550 m/z)

Carrier gases were H₂ or He with typical flow rates (1.1–1.35 mL/min). Injector temperatures were 250°C with split ratios of 1:75 or 1:100.

Main Results and Discussion

Bleed levels on HT-WAX remained below 5 pA up to 280°C (0.8 pA at 250°C, 1.5 pA at 260°C, 1.9 pA at 270°C, 4.0 pA at 280°C) and rose to ~13.4 pA at 290°C. Commercial WAX benchmarks exhibited ~17 pA at 250°C. After 50 h conditioning at 250°C, HT-WAX showed stable low bleed and minimal baseline drift, outperforming competitors in longevity.
Inertness assessments demonstrated sharp, symmetric peaks for both test mixes. Phenolic compounds (~45 pg on-column) yielded higher signal-to-noise on HT-WAX versus the lowest-bleed commercial WAX. Chromatograms confirmed reduced tailing and improved peak shape, indicating superior inertness.

Benefits and Practical Applications of the Method

• Enhanced detection limits due to ultra-low bleed
• Extended operational range up to 280–290°C, broadening analyte scope
• Improved reproducibility and column lifetime in GC and GC/MS
• Compatibility with GC×GC as a second-dimension polar phase without major method changes
• Easy integration in existing workflows, reducing re-validation effort

Future Trends and Opportunities for Use

Further developments may:

• Enable stable operation beyond 290°C
• Support faster temperature programming for high throughput analyses
• Expand applications to complex petrochemical or environmental samples
• Integrate with advanced detectors and comprehensive two-dimensional systems
• Incorporate novel surface chemistries to tailor selectivity

Conclusion

The HT-WAX column represents a significant advancement in PEG-based stationary phases, delivering ultra-low bleed, robust inertness and an extended temperature range. This platform enhances sensitivity, durability and flexibility for GC, GC/MS and GC×GC analyses with minimal method adaptation.

References

1. Biermans F., Duvekot J. Patent Chromatography columns US 9034186 B2 (2005)
2. Oostdijk J., Dang N.A. New definition for maximum allowable operating temperature of WAX GC columns. Poster B.02, 40th ISCC (2016)