A hydrodynamic injection approach for capillary electrophoresis using rotor-stator valves

Area of Science:

• Analytical Chemistry
• Separation Science
• Capillary Electrophoresis (CE)

Background:

• Sample injection is crucial for capillary electrophoresis (CE) analysis.
• Electrokinetic injection is common in portable CE but susceptible to matrix effects.
• Hydrodynamic injection is preferred for minimizing matrix effects but typically limited to the grounded end, restricting detector coupling.

Purpose of the Study:

• To develop a high-voltage (HV)-compatible hydrodynamic injection method for CE.
• To overcome limitations of previous HV injection methods, such as peak tailing and mixing.
• To enable improved coupling with detectors like mass spectrometry (MS).

Main Methods:

• Development of an HV-compatible hydrodynamic injection system for capillary electrophoresis.
• Analysis of a 13-amino acid mixture using CE coupled with laser-induced fluorescence (LIF).
• Analysis of amino acids, peptides, nucleobases, and nucleosides using CE coupled with electrospray ionization-mass spectrometry (CE-ESI-MS).

Main Results:

• CE-LIF analysis of amino acids showed relative standard deviations below 5% for peak area and 1% for migration time in triplicate measurements.
• CE-ESI-MS analysis demonstrated minimal peak tailing, comparable to commercial CE-ESI-MS setups.
• The new method successfully overcomes issues of peak tailing and undesired mixing associated with previous HV injection approaches.

Conclusions:

• The developed HV-compatible hydrodynamic injection method enhances capillary electrophoresis performance.
• This technique offers improved analytical accuracy and precision for complex sample matrices.
• The method facilitates versatile coupling with advanced detection techniques, broadening CE applications.