Gradient elution electrochromatography with a flow-injection analysis interface

Area of Science:

• Analytical Chemistry
• Separation Science
• Chromatography

Background:

• Gradient elution in capillary electrochromatography (CEC) offers enhanced separation capabilities.
• Traditional CEC methods face challenges with solvent gradient generation and column longevity.
• Online injection systems are crucial for automated and reproducible CEC analyses.

Purpose of the Study:

• To develop and evaluate a novel flow-injection analysis (FIA)-CEC interface for gradient elution.
• To assess the performance of the interface in terms of separation efficiency, reproducibility, and column lifetime.
• To demonstrate the capability of the interface for analyzing complex mixtures using gradient CEC.

Main Methods:

• A micro-liquid chromatography (LC) system was coupled to an FIA-CEC interface for gradient solvent generation.
• Online injections were performed using an electrically actuated rotary LC valve.
• Gradient shapes were characterized, and a test mixture of nine solutes was analyzed under isocratic and gradient elution conditions.

Main Results:

• The FIA-CEC interface successfully generated solvent gradients for gradient elution CEC.
• Baseline separation of nine solutes was achieved in under 18 minutes using a MeCN-water gradient.
• Reproducibility of retention times was better than 2% R.S.D., and column lifetime was improved due to reduced column movement.

Conclusions:

• The developed FIA-CEC interface is effective for gradient elution CEC, providing rapid and reproducible separations.
• The interface simplifies gradient generation and enhances operational convenience, including autoinjector compatibility.
• This technology offers a promising approach for improving the efficiency and longevity of capillary electrochromatography systems.