Capillary Electrophoresis

Abstract Capillary electrophoresis is an electric field‐mediated microseparation technique that utilises narrow‐bore fused‐silica capillaries (10–100 μm) and high applied electric fields (100–1000 V/cm) enabling short analysis times with high separation efficiency and excellent resolution, whereas the narrow bore capillary readily dissipates the generated Joule heat. The main separation modes of capillary electrophoresis are capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), capillary isoelectric focusing (cIEF), capillary gel electrophoresis (CGE) and capillary electrochromatography (CEC). As a truly orthogonal method to high‐performance liquid chromatography (HPLC), capillary electrophoresis is recently gaining high importance in the pharmaceutical, biotechnology and biomedical industries, especially for the analysis of protein therapeutics. Key Concepts: Capillary electrophoresis (CE) is a truly orthogonal separation method to chromatography‐based techniques. CE is a fully automated approach to electrophoresis. The narrow bore capillaries used in CE enable application of high separation voltages without significant heat generation. Electroendoosmotic flow (EOF) generates a bulk fluid flow within the narrow bore capillary and therefore one of the driving forces of CE analysis. The main separation modes of CE are: Capillary zone electrophoresis (CZE) separation is based on free solution mobility; micellar electrokinetic chromatography (MEKC) utilises partitioning of hydrophobic analytes within charged micelles; capillary gel electrophoresis (CGE) applies sieving polymers for size separation of macromolecules; and capillary isoelectric focusing (cIEF) separates amphoteric analytes based on their charge states; and capillary electrochromatography (CEC) based on the interplay between electric field and chromatography‐mediated separations. CE is one of the emerging separation techniques in the biotechnology, biopharmaceutical and biomedical industries. Microfluidics devices integrate the concept of CE with fluidics sample manipulation such as on chip sample preparation.