Organic solvent high-field amplified stacking for basic compounds in capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Separation Science

Background:

• Electrokinetic injection is a common technique in capillary electrophoresis.
• Achieving significant stacking, or sample enrichment, is crucial for enhancing detection sensitivity.

Purpose of the Study:

• To investigate the effect of water-miscible organic solvents on stacking efficiency during high-field amplified injection.
• To explore the practical applicability of organic solvent-based electrokinetic injection for sample analysis.

Main Methods:

• High-field amplified injection coupled with capillary electrophoresis.
• Comparison of stacking efficiency in aqueous buffers versus organic solvents (acetonitrile, acetone).
• Analysis of basic compounds, including cationic drugs in serum after protein precipitation.

Main Results:

• Organic solvents like acetonitrile and acetone enhanced stacking by approximately 30-fold compared to aqueous buffers.
• The relative stacking order of compounds differed between organic and aqueous media.
• Organic solvent high-field amplified injection demonstrated robustness against acids and salts, especially when samples were diluted in acetonitrile.
• This method showed superior or comparable performance to pressure injection and enabled therapeutic level detection of amiodarone in serum.

Conclusions:

• Organic solvent high-field amplified injection is a powerful technique for enhancing the detection of basic compounds in capillary electrophoresis.
• This method offers practical advantages, including improved sensitivity and simplified sample preparation, particularly for complex matrices like serum.