WAX Column Technology Update

Significance of the Topic

Polar GC stationary phases based on polyethylene glycol (PEG), known as WAX columns, play a vital role in analyzing polar analytes such as alcohols, glycols, organic acids, free fatty acids and flavor compounds. Their high polarity complements non-polar columns in comprehensive GC workflows, enabling reliable separations in food analysis, petrochemistry, environmental monitoring and quality control.

Study Objectives and Overview

This whitepaper presents an update to Agilent’s WAX column portfolio, focusing on new or improved phases: HP-INNOWax, CP-WAX 52 CB, DB-WAX Ultra Inert (UI), DB-FATWAX UI and DB-HeavyWAX. The goal is to demonstrate enhancements in inertness, thermal stability, bleed performance, reproducibility and selectivity across typical WAX applications.

Applied Instrumentation

Evaluation was conducted primarily on an Agilent 7890B GC equipped with FID detection. Carrier gases (helium, hydrogen or nitrogen) and flow modes were optimized for each test. Column dimensions ranged from 10 m to 60 m in length, 0.10 mm to 0.32 mm internal diameter, film thicknesses 0.10–0.50 µm. Temperature programs extended to 280–290 °C for DB-HeavyWAX trials.

Methodology

Performance was assessed using:

• Standard test mixtures (ketones, phenols, acids, alkanes) to gauge inertness and bleed after extended high-temp cycles.
• Real-world samples including lavender oil, menhaden fish oil, distilled beverages, water-soluble organic acids and pyrolysis gasoline.
• FAME/ fatty acid profiling with EPA/DHA critical pair resolution and trans-cis isomer separations.
• Retention time stability tests up to maximum allowable operating temperatures (MAOT).

Key Results and Discussion

• HP-INNOWax and CP-WAX 52 CB exhibit improved column inertness and reproducibility for diols, amines and acids, tolerating repeated cycles to upper temperature limits.
• DB-WAX Ultra Inert achieves superior peak shape and low bleed, replacing acid-modified FFAP columns for free fatty acid analysis without derivatization.
• DB-FATWAX UI offers exceptional inertness and selectivity for saturated and polyunsaturated FAMEs, organic acids and fish-oil matrices, fully resolving challenging C24:0/DHA pairs and VOCs in water.
• DB-HeavyWAX extends WAX polarity into higher temperature regimes (isothermal to 280 °C, programmed to 290 °C) with minimal bleed, stable retention, reduced carry-over and shorter runtimes for high-boiling compounds and GC×GC workflows.

Benefits and Practical Applications

These improved WAX phases deliver:

• Enhanced signal-to-noise ratios via reduced bleed at elevated temperatures.
• Stable retention times and selectivity over prolonged high-temperature use.
• Elimination of derivatization steps for organic acid analyses, streamlining QA/QC.
• Flexible column choices for food/flavor profiling, petro-aromatics, biodiesel FAME testing and environmental VOC monitoring.

Future Trends and Applications

Ongoing development will likely focus on:

• Further lowering of bleed while increasing MAOT for next-generation WAX phases.
• Integration with comprehensive GC×GC-MS techniques for broader analyte coverage.
• Automated, high-throughput workflows in industrial QA/QC leveraging ultra-inert columns.
• Expanded applications in metabolomics, lipidomics and environmental micro-contaminant analysis.

Conclusion

Agilent’s updated WAX column portfolio offers a versatile set of tools for polar compound separations. From enhanced inertness in DB-WAX UI and DB-FATWAX UI to the high-temperature capability of DB-HeavyWAX, analysts gain improved sensitivity, stability and throughput across diverse applications.