Agilent ZORBAX Eclipse Plus C18 - Data Sheet

Importance of the topic

The analysis of acidic, basic and polar compounds by reverse-phase liquid chromatography is essential in fields such as pharmaceutical development, environmental monitoring and quality control. Achieving sharp, reproducible peaks for diverse analytes requires columns with minimal secondary interactions and robust performance across variable conditions. The Agilent ZORBAX Eclipse Plus C18 packing addresses these challenges through optimized surface chemistry and rigorous quality control.

Objectives and Study Overview

This summary reviews the design principles, performance characteristics and practical guidelines for the Eclipse Plus C18 column. Key aims include explaining the stationary phase construction, evaluating chromatographic performance under standard conditions and outlining recommended practices for operation and maintenance.

Methodology

The stationary phase comprises a dense monolayer of dimethyl-n-octadecylsilane chemically bonded to ultra-high-purity (>99.995% SiO₂) ZORBAX Rx-SIL porous silica. A proprietary double endcapping process deactivates residual silanol groups, reducing undesired adsorption. Uniform particle size (5 µm), surface area (160 m²/g) and pore diameter (95 Å) are achieved via high-pressure slurry loading, delivering consistent bed density and high efficiency.

Instrumentation

• Column: Eclipse Plus C18, 4.6 mm × 150 mm, 5 µm
• Mobile phase: 85% methanol / 15% water
• Flow rate: 1.0 mL/min
• Temperature: ambient
• Injection volume: 5 µL
• Detector: UV at 254 nm
• Test analytes: Uracil (5 µg/mL), Phenol (200 µg/mL), 4-Chloronitrobenzene (25 µg/mL), Toluene (850 µg/mL)

Main Results and Discussion

Quality control chromatograms demonstrate sharp, symmetric peaks for both neutral and ionizable analytes, confirming minimal secondary interactions. The column delivers high efficiency and excellent peak shape across a broad pH range (2–9) and tolerates pressures up to 400 bar and temperatures up to 60 °C. Endcapping significantly improves performance for basic and highly polar compounds compared to conventional C18 packings.

Benefits and Practical Applications

• Superior peak shape for basic and polar analytes
• Wide operational pH range with extended column lifetime
• Compatibility with water, methanol, acetonitrile and common buffers
• Suitable for pharmaceutical assays, environmental analyses and food testing
• Use of guard columns recommended to protect and prolong packing life

Future Trends and Potential Applications

Advances in column technology are moving toward smaller particles (<2 µm), core–shell designs and novel stationary phases offering even greater inertness and pH stability. Integration of advanced materials promises further reduction of non-specific interactions. These developments will enhance high-throughput screening, metabolomics and proteomics workflows.

Conclusion

The Agilent ZORBAX Eclipse Plus C18 column provides a robust, high-efficiency solution for the separation of acidic, basic and polar compounds in reverse-phase LC. Its specialized bonding and endcapping deliver reproducible performance, broad pH compatibility and long operational life, making it a versatile choice for diverse analytical challenges.

Reference

• Agilent Technologies, ZORBAX Eclipse Plus C18 Data Sheet, April 2006.
• Claessens H. A., van Straten M. A., Kirkland J. J., J. Chromatogr. A, 728 (1996) 259.