Capillary Electrophoresis: Instrumentation

Capillary electrophoresis instrumentation includes a high-voltage power supply connected to an anode and a cathode placed in buffer reservoirs, a sample vial, a fused silica capillary tube, and a detector.

The buffer-filled capillary tube is coated with polyimide for mechanical strength and connected to two buffer reservoirs containing electrodes.

Sample introduction involves detaching one end of the capillary and its electrode from the associated buffer reservoir and placing it in the sample vial.

Hydrodynamic injection uses pressure, while electrokinetic injection applies an electric field to introduce the sample into the capillary tube.

If the sample concentration is too low, it is injected into a solution of lower ionic strength than the buffering solution to enhance its detection through a stacking technique.

Applying a high voltage across the buffer system causes charged species to move toward the cathode via electroosmotic flow.

The separation of components occurs based on their electrophoretic mobility within the electric field.

Detectors based on absorption, fluorescence, conductivity and mass spectrometry are commonly used in CE.