System zones in capillary zone electrophoresis

Area of Science:

• Analytical Chemistry
• Separation Science
• Electrophoresis

Background:

• Capillary zone electrophoresis (CZE) systems become non-homogeneous upon sample injection.
• Analyte injection disturbs the background electrolyte (BGE) concentration, creating persistent inhomogeneities.
• These inhomogeneities propagate as system zones (eigenzones) with distinct mobilities, appearing as system peaks in electropherograms.

Purpose of the Study:

• To review the theoretical basis for the formation of system zones and system peaks in CZE.
• To discuss the applicability of the Kohlrausch regulating function in complex BGE systems.
• To provide practical guidance for preparing BGEs that minimize system peaks and peak broadening for improved separations.

Main Methods:

• Theoretical analysis of electromigration phenomena in CZE.
• Application of advanced computer software for modeling complex BGE systems.
• Review of experimental observations and their theoretical explanations.

Main Results:

• System zones are an inherent characteristic of CZE, arising from BGE concentration disturbances.
• Theoretical frameworks now allow for the prediction and treatment of system zones even in complex BGEs across various pH ranges.
• It is possible to predict BGEs that lack stationary injection zones, such as water or EO zones.

Conclusions:

• A thorough understanding of system zone origins is essential for CZE analysts.
• Effective BGE preparation can mitigate the negative impact of system peaks and excessive peak broadening.
• Advanced theoretical models aid in managing and predicting these phenomena in sophisticated separation systems.