Size-exclusion electrochromatography with controlled pore flow

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Size-exclusion electrochromatography (SEEC) relies on an optimal pore-to-interstitial flow ratio for maximizing chromatographic resolution.
• Controlling this flow ratio is crucial for effective separations, particularly with different particle pore sizes.

Purpose of the Study:

• To investigate two methods for controlling the pore-to-interstitial flow ratio in SEEC: mobile phase ionic strength adjustment and superimposed hydrodynamic flow.
• To evaluate the efficiency and applicability of these methods using silica particles with 10 nm and 50 nm pores.

Main Methods:

• Method 1: Modifying mobile phase ionic strength to alter flow ratios.
• Method 2: Applying external pressure (hydrodynamic flow) in conjunction with electroosmotic flow.
• Chromatographic analysis using silica particles of 10 nm and 50 nm pore diameters with varying ionic strength mobile phases.

Main Results:

• Varying ionic strength effectively adjusted the flow ratio for 10 nm pore particles but was insufficient for 50 nm pore particles.
• Superimposed hydrodynamic flow (pressure) proved applicable to both particle types, enabling precise control over the pore-to-interstitial flow ratio.
• Pressurized SEEC significantly improved separation efficiency due to enhanced mass transfer from intra-particle electroosmotic flow, achieving efficiencies comparable to pure SEEC.

Conclusions:

• Superimposed hydrodynamic flow is a versatile method for optimizing pore-to-interstitial flow ratios in SEEC across different particle types.
• Pressurized SEEC offers a powerful approach to enhance separation efficiency while minimizing selectivity loss compared to pressure-driven size-exclusion chromatography.