Transfer of Methods between Poroshell 120 EC-C18 and ZORBAX Eclipse Plus C18 Columns

Significance of Topic

The comparison and transfer of reversed-phase liquid chromatography methods between superficially porous particle columns and sub-2 µm totally porous particle columns addresses key practical needs in analytical laboratories. Superficially porous columns such as Agilent Poroshell 120 EC-C18 combine high efficiency with reduced backpressure, enabling faster separations or longer columns without overloading system pressure limits. Demonstrating equivalence in selectivity and retention across a broad range of conditions supports method scalability from development to high-throughput and preparative workflows.

Study Objectives and Overview

This work evaluates the chromatographic equivalence of Agilent Poroshell 120 EC-C18 (2.7 µm superficially porous) and Agilent ZORBAX Eclipse Plus C18 (1.8 µm totally porous) columns. The goals were to compare retention behavior and selectivity over a wide pH range (3–6.5) in both acetonitrile- and methanol-based mobile phases, to assess backpressure differences under gradient conditions, and to confirm reliable method transfer in routine analyses of diverse compound classes.

Methodology and Instrumentation

A generic gradient (5→95 % organic over 2 min, hold 1 min) was applied at 2 mL/min using mobile phases buffered with 10 mM ammonium formate or acetate adjusted to pH 3.0, 3.8, 4.8, and 6.5. A set of 66 compounds encompassing environmental phenols, soft drink additives, acids, bases, and neutrals were injected individually to generate retention data for scatter-plot correlation. Pressure vs linear velocity profiles were recorded for 3 × 100 mm columns under representative solvent mixtures of 45/55 methanol/water and 10/90 acetonitrile/water at 25 °C.

Used Instrumentation

• Agilent 1200 Method Development LC System
• G1312B Binary Pump SL
• G1367D Automatic Liquid Sampler SL
• Two G1316C Thermostatted Column Compartments SL
• G1315C Diode Array Detector with 3 mm path/2 µL micro-flow cell
• ChemStation B.04.01 software for control and data processing

Main Results and Discussion

Retention time correlations between Poroshell 120 EC-C18 and Eclipse Plus C18 showed slopes near unity (0.985–0.993 with acetonitrile, 1.010–1.041 with methanol) and high coefficients of determination (R2 > 0.996), indicating almost identical selectivity across pH 3–6.5. Scatter plots of 66 compounds revealed proportional shifts in retention for ionizable species, reflecting similar hydrophobic and secondary interactions on both chemistries. Pressure profiling demonstrated that Poroshell 120 EC-C18 exhibits approximately 40 % lower backpressure than a 1.8 µm column at equivalent linear velocities, facilitating higher flow rates or longer column formats.

Benefits and Practical Applications

• Direct method transfer: Established sub-2 µm methods can be migrated to superficially porous columns with minimal reoptimization.
• Higher throughput: Lower pressure allows faster gradients or elevated flow rates on standard HPLC systems.
• Enhanced resolution options: Users can extend column length to improve separations without exceeding pressure limits.
• Versatility: Comparable performance with volatile MS-compatible buffers across a wide pH range supports diverse analyte classes.

Future Trends and Possibilities

Ongoing developments in superficially porous particle technology may expand pore sizes and surface chemistries to accommodate larger biomolecules or improve shape selectivity for polyaromatic compounds. Integration with ultra-high-throughput platforms and two-dimensional separations could further leverage low backpressure benefits. Additionally, coupling these columns with high-resolution mass spectrometry promises enhanced analytical workflows in proteomics, metabolomics, and environmental monitoring.

Conclusion

This comprehensive evaluation confirms that Agilent Poroshell 120 EC-C18 columns reproduce the selectivity of Agilent ZORBAX Eclipse Plus C18 columns across a broad range of mobile phase compositions and pH values while offering significantly reduced backpressure. Laboratories can confidently transfer or interchange methods between these column families, achieving high efficiency, flexibility in throughput, and extended column formats without sacrificing chromatographic performance.

References

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