Phenomenex ZB-624PLUS

Significance of the Topic

Gas chromatography (GC) relies on inert column surfaces and stable stationary phases to achieve accurate quantitation of volatile and semi-volatile analytes. Challenges such as adsorption of active compounds, column bleed, and thermal limitations can compromise peak shapes, sensitivity, and reproducibility. The Zebron™ ZB-624PLUS™ GC column series addresses these issues by combining advanced deactivation chemistry with a versatile stationary phase, enabling robust detection across environmental, pharmaceutical, food, and specialty chemical applications.

Study Objectives and Overview

• Develop a GC column with superior inertness for polar and high-boiling analytes.
• Enhance thermal stability and reduce bleed to improve signal-to-noise ratio in GC and GC–MS analyses.
• Evaluate column performance in key applications such as USP <467> residual solvent detection, EPA VOC methods, and cannabis profiling.
• Compare the new ZB-624PLUS phase against competitive 624 phases in terms of bake-out stability, peak shape, and reproducibility.

Methodology and Instrumentation

The ZB-624PLUS columns undergo an Engineered Self Cross-Linking (ESC™) process and proprietary deactivation to minimize active sites. Performance was assessed using:

• GC–FID for residual solvent and amine analysis on a 30 m × 0.32 mm × 1.8 µm ZB-624PLUS column with a Zebron PLUS Straight Z-Liner™.
• High-temperature bake-out tests up to 300/320 °C over 115 h to monitor bleed and retention consistency.
• GC–MS VOC screening (EPA 8260, 524, 624) at ppb levels on a 30 m × 0.25 mm × 1.4 µm ZB-624PLUS (MS certified) with helium carrier gas.
• Comparative separations against commercial 624 phases from Agilent® and Restek®.

Main Results and Discussion

• Bake-out Stability: Low bleed persisted after 115 h at 300 °C, with consistent sensitivity and retention.
• Inertness for Volatile Amines: ZB-624PLUS delivered sharp peaks and high signal even at 50–500 ppm, outperforming competitor inert 624 phases.
• Residual Solvent Screening: Achieved resolutions exceeding USP <467> system suitability (Rs > 1.5) for Class 1–3 solvents, including challenging pairs like pyridine.
• High-Throughput Methods: A 15 min GC–FID residual solvent method showed baseline resolution of nine common solvents, reducing analysis time by > 75 %.
• VOC GC–MS Performance: A 74-compound mix eluted in < 15 min with minimal bleed and stable baselines; ppb-level detection maintained after > 100 real sample injections.
• Cannabis Profiling: Comprehensive terpene separations and combined residual solvent analysis on a single ZB-624PLUS column simplified workflows and avoided column changes.
• Solvent Purity Checks: Key impurities in acetone, ethyl acetate, THF, and DMF were resolved efficiently, demonstrating broad applicability.

Benefits and Practical Applications of the Method

• Enhanced peak shapes for active and high-boiling analytes reduce quantitation errors.
• Lower detection limits in GC–MS and GC–FID due to reduced column bleed.
• High column-to-column reproducibility supports method validation in regulated environments.
• Single-column solution for diverse analyses—including residual solvents, VOCs, and terpenes—improves lab productivity.
• Extended bake-out and high-temperature capability up to 320 °C allows thorough contaminant removal and late-eluting analyte elution.

Future Trends and Applications

Advances in column deactivation and phase chemistry will continue to enhance GC inertness, enabling even trace-level analysis of polar and labile compounds. Future directions include:

• Integration with advanced sample introduction (e.g., cold trapping, headspace autosamplers) for ultratrace applications.
• Hybrid stationary phases combining 624 selectivity with chiral or ionic interactions for more complex sample matrices.
• Automated gas purity management and inert liners to further reduce maintenance and downtime.
• Applications expanding into metabolomics, forensic toxicology, and complex environmental screening.

Conclusion

The Zebron ZB-624PLUS GC column series offers a next-generation solution for inertness, sensitivity, and thermal stability in gas chromatography. By addressing common challenges—adsorption, bleed, and reproducibility—ZB-624PLUS supports rigorous quantitative and qualitative analyses across multiple industries, streamlining workflows and delivering reliable, high-quality data.

References

• Phenomenex Inc., Zebron ZB-624PLUS Product Brochure, 2018.