Improve performance for basic analytes with low ionic strength mobile phases

Significance of the Topic

The analysis of basic compounds often suffers from poor peak shapes when using low ionic strength mobile phases in liquid chromatography. InfinityLab Poroshell 120 CS-C18 technology addresses this challenge by enabling improved chromatographic performance for analytes that require formic acid mobile phases without the complexity of buffer additives.

Objectives and Study Overview

• Establish a rapid, reproducible LC method for basic analytes using formic acid mobile phase.
• Compare performance of Poroshell 120 CS-C18 columns against conventional C18 phases with and without buffer.

Methodology and Instrumentation

The study employed superficially porous 2.7 µm Poroshell 120 CS-C18 columns coupled to an Agilent InfinityLab LC/MS system. Mobile phases included 0.1% formic acid and 5 mM ammonium formate. Chromatographic performance was evaluated by peak width, symmetry, and LC/MS sensitivity for basic probe compounds.

Main Results and Discussion

• Poroshell CS-C18 with formic acid yielded sharper peaks (peak widths reduced by up to 50%) compared to traditional C18.
• Metoprolol SNR of 311.9 on Poroshell vs 83.2 on conventional C18 with buffer.
• Superficially porous particles delivered comparable resolution to sub-2 µm phases at half the backpressure.
• Columns demonstrated stable performance across a wide pH range, enhancing method robustness.

Benefits and Practical Applications

• Simplified mobile phase composition avoiding high ionic strength buffers.
• Higher throughput through faster separations at standard HPLC pressures.
• Improved load capacity and peak shape for basic pharmaceuticals and metabolites.
• Enhanced LC/MS sensitivity with reduced ion suppression.

Future Trends and Possibilities

• Broader adoption of superficially porous stationary phases in routine analysis.
• Development of novel phases for extreme pH stability and selectivity.
• Integration with ultrahigh-throughput and automated workflows.
• Movement towards greener, additive-free mobile phases.

Conclusion

InfinityLab Poroshell 120 CS-C18 columns offer a robust solution for the analysis of basic compounds with low ionic strength mobile phases, combining simplicity, speed, and sensitivity in modern LC and LC/MS applications.

Reference

• Agilent Technologies. Application Note 5994-2094EN, 2020.