Titanium dioxide coated surfaces for capillary electrophoresis and capillary electrochromatography

Area of Science:

• Analytical Chemistry
• Materials Science

Background:

• Capillary electrophoresis (CE) and capillary electrochromatography (CEC) are powerful separation techniques.
• Controlling electroosmotic flow (EOF) is crucial for optimizing separation efficiency in CE and CEC.
• Titanium dioxide (TiO2) is a versatile material with potential surface modification capabilities.

Purpose of the Study:

• To evaluate titanium dioxide coatings for controlling electroosmotic flow (EOF) in fused-silica capillaries.
• To investigate the effect of TiO2 coatings on analyte migration in CE and open-tubular CEC.
• To assess the performance of modified TiO2 surfaces for separating diverse analytes.

Main Methods:

• Fused-silica capillaries were coated with a titanium peroxo complex and heated to form crystalline anatase TiO2.
• Surface characterization was performed using Fourier transform-infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy, and Raman spectroscopy.
• The TiO2-coated capillaries were further modified using a silanizing reagent.

Main Results:

• The TiO2 coatings resulted in tunable EOF, which could be anodic or cathodic depending on background electrolyte pH and composition.
• The TiO2 surface demonstrated facile modification with silanizing reagents.
• The performance of modified and unmodified TiO2 surfaces was successfully tested for the separation of inorganic anions, neutral compounds, and peptides.

Conclusions:

• Titanium dioxide coatings provide a viable strategy for controlling EOF in capillary-based separations.
• The ability to chemically modify the TiO2 surface expands its utility for tailored chromatographic applications.
• These modified capillaries show promise for enhanced separation of various analytes in CE and CEC.