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Separation of acidic and basic compounds in capillary electrochromatography with polymethacrylate-based monolithic
Guichen Ping1, Lihua Zhang, Lin Zhang
1National Chromatographic Research and Analysis Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116011, China.
Journal of Chromatography. A
|May 6, 2004
Summary
New methacrylate monolithic columns enable efficient separation of acidic and basic compounds using electroosmotic flow (EOF) or minimal EOF, offering versatile chromatography solutions.
Area of Science:
- Analytical Chemistry
- Chromatography Science
- Materials Science
Background:
- Development of novel stationary phases for chromatography is crucial for improving separation efficiency.
- Methacrylate-based monolithic columns offer advantages in terms of permeability and surface area.
- Electroosmotic flow (EOF) plays a significant role in capillary electrochromatography performance.
Purpose of the Study:
- To prepare and characterize methacrylate-based monolithic columns for the separation of acidic and basic compounds.
- To evaluate the performance of these columns under varying pH conditions with different electroosmotic flow (EOF) characteristics.
- To investigate the separation mechanisms and optimize conditions for both acidic and basic analyte classes.
Main Methods:
- In situ copolymerization of methacrylate monomers in fused-silica capillaries with a porogen.
- Surface pretreatment of capillaries with a bifunctional reagent to ensure proper bonding.
- Capillary electrochromatography (CEC) using columns with controlled EOF (low and high pH).
- Analysis of acidic and basic compound mixtures to assess separation efficiency and peak shape.
Main Results:
- Successfully prepared methacrylate monolithic columns exhibiting tunable EOF.
- Achieved satisfactory separations of acidic compounds at low pH with high EOF mobility (1.74 x 10^-4 cm^2 s^-1 V^-1).
- Demonstrated effective separation of seven acidic compounds within 5.7 minutes.
- Obtained good peak shapes for basic compounds at high pH without masking amines due to minimized secondary interactions.
- Identified a reversed-phase separation mechanism for both acidic and basic compounds.
Conclusions:
- Methacrylate monolithic columns are effective for separating both acidic and basic compounds.
- Tunable EOF allows for optimized separations across a range of pH conditions.
- Minimized secondary interactions at high pH enhance the separation of basic analytes.
- These columns present a promising alternative for various chromatographic applications.