Now There’s A WAX Column That Can Take The Heat

Significance of the Topic

The development of high-temperature polyethylene glycol GC columns expands analytical capabilities by combining polarity with enhanced thermal tolerance. WAX columns traditionally limit analysis of heavy or high-boiling analytes due to stationary phase degradation and column bleed above 250 °C. By extending temperature limits to 280–290 °C while maintaining PEG selectivity, analysts can improve throughput, data reliability, and broaden application scope in industries such as petrochemicals, flavor and fragrance profiling, and environmental testing.

Study Objectives and Overview

This work introduces the Agilent J&W DB-HeavyWAX GC column, designed to operate isothermally up to 280 °C and in temperature programs to 290 °C. The study aims to compare its thermal stability, retention time consistency, column bleed, and selectivity against conventional WAX columns, using standard BTEX mixtures, cold-pressed grapefruit oil, and pyrolysis gasoline samples.

Instrumentation

• Column: Agilent J&W DB-HeavyWAX (e.g., 60 m × 0.25 mm × 0.25 µm)
• Gas chromatograph: Agilent 7890B GC with FID detector
• Carrier gas: Helium at 1.0–1.2 mL/min constant flow
• Autosampler: Agilent 7693
• Temperature program: initial hold at 70 °C, ramp rates 5–20 °C/min to final 280 °C

Methodology and Analytical Approach

• Thermal stability test: Continuous isothermal operation at 280 °C for up to 100 hours, monitoring retention time shifts for o-xylene and BTEX standard.
• Column bleed assessment: Measurement of baseline bleed current after extended use at 280 °C compared to two commercial WAX columns.
• Grapefruit oil analysis: Comparison of ghost peak formation and carryover effects when final temperature held at 250 °C and extended to 280 °C.
• Pyrolysis gasoline application: Selectivity evaluation under ASTM D6563 to assess compatibility with existing WAX methods.

Key Results and Discussion

• Retention time stability: Agilent J&W DB-HeavyWAX showed negligible retention shift (<0.1 min) after 100 hours at 280 °C, whereas standard WAX columns drifted by ~2 minutes.
• Column bleed: Bleed currents remained <10 pA on DB-HeavyWAX, compared to 50–60 pA on competitor WAX columns after 100 hours.
• Carryover reduction: At 280 °C final temperatures, heavy components in grapefruit oil eluted cleanly without ghost peaks in subsequent injections.
• Throughput improvement: Higher temperature capability reduced run times by ~20%, improving laboratory efficiency.
• Selectivity retention: Comparable separation profiles for industrial compounds, flavors, and BTEX, enabling method transfer from existing WAX protocols.

Advantages and Practical Applications

• Extended temperature range without compromising PEG phase selectivity.
• Improved thermal stability and reproducibility over column lifetime.
• Minimized bleed and ghost peaks, enhancing sensitivity and data quality.
• Faster analysis for high-boiling and heavy-matrix samples in petrochemical, flavor, fragrance, and environmental sectors.
• Suitable for GC×GC and high-resolution GC/MS workflows requiring durable polar columns.

Future Trends and Potential Applications

With increasing demand for comprehensive profiling of complex matrices, robust high-temperature polar columns will enable:

• Advanced multidimensional GC analyses for petroleum and petrochemical sectors.
• Expanded use in GC-MS/MS for trace-level detection in food safety and environmental monitoring.
• Integration into high-throughput screening platforms in pharmaceutical and flavor research.
• Development of next-generation PEG phases with even higher temperature limits and tailored selectivity.

Conclusion

The Agilent J&W DB-HeavyWAX column addresses key limitations of traditional WAX phases by providing an extended upper temperature limit (280–290 °C) while preserving polar selectivity. It offers stable retention, low bleed, and reduced carryover, resulting in faster, more reliable analyses across a broad spectrum of applications without requiring major method changes.

Reference

1. ASTM D2306 Standard Test Method for C8 Aromatic Hydrocarbon Analysis by Gas Chromatography
2. ASTM D6563 Standard Test Method for Benzene, Toluene, Xylene (BTX) Concentrates Analysis by Gas Chromatography