Linear voltage profiles and flow homogeneity in pressurized planar electrochromatography

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Planar electrochromatography (PEC) utilizes electroosmosis for solvent transport, offering faster flow rates and higher efficiencies than traditional thin-layer chromatography (TLC).
• Low-pressure PEC systems exhibit unstable electroosmotic flow (EOF) due to non-linear voltage drops across the separation path.

Purpose of the Study:

• To investigate the performance of high-pressure PEC, termed pressurized planar electrochromatography (PPEC), in achieving stable EOF and linear voltage drops.
• To compare PPEC with low-pressure PEC regarding plate equilibration, field strength utilization, and sample application.

Main Methods:

• Utilized a unique reader electrode grid to monitor voltage at eight discrete positions along a 10-cm separation path.
• Compared plate equilibration times, field strengths, and sample application designs between PPEC and low-pressure PEC.
• Investigated rhodamine B as a visual marker for reproducible migration and theoretical plate calculations.

Main Results:

• High-pressure PEC (PPEC) instruments demonstrate linear voltage drops and constant EOF.
• PPEC shows advantages in plate equilibration times compared to low-pressure PEC.
• Rhodamine B serves as an effective visual marker for migration reproducibility.

Conclusions:

• PPEC overcomes the limitations of low-pressure PEC by providing stable EOF and linear voltage profiles.
• The findings support PPEC as a more robust and efficient technique for planar chromatography.
• Optimized instrumental designs and markers like rhodamine B further enhance PEC applications.