Sample inlets electromigration

Sample injection is an event common to all modes of CE except CIEF, and the most relevant aspects of this step are described here. Because the total volume of the capillary is very low, sample injection in CE requires the precise introduction of very small amounts of analyte at the capillary inlet. There are two basic procedures for sample injection electromigration and hydraulic displacement. All commercial instruments offer electromigration, or electrophoretic, injection and at least one type of displacement injection. 

Electrokinetic (also called electromigration) injection is performed by placing the inlet of the capillary and an electrode in the sample vial. Following this a voltage is applied during a defined period of time. The sample constituents are actively carried into the capillary, and when present, the EOF also passively carries them into the capillary. For this reason, neutral compounds are also injected. The active migration is due to the effective electrophoretic mobilities of the constituents. The amount (B), in units of concentration injected into the capillary is expressed by [2,38]... 

Electromigration (also known as electrophoretic) injection. The capillary inlet is inunersed in the sample vial and a high voltage applied (usually three to five times lower than used for separation) for a controlled... 

Sample injection in CE requires the introduction of very small amounts of analyte at the capillary inlet with high precision. All commercial instruments offer electromigration injection and at least one type of displacement injection. 

Electromigration is the simplest injection method in CE the capillary inlet is immersed in the sample solution and high voltage is applied for a brief period (typically a few seconds). If no electroosmotic flow is present, sample ions enter the capillary by electophoretic mobility alone this mode of sample introduction is termed electrophoretic injection. If EOF is present, sample ions will be introduced by a combination of electrophoretic mobility and electroosmotic flow this mode is generally termed electrokinetic injection. 

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