Reverse direction capillary electrophoresis: theory and application



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Texas Tech University


The history of Capillary Electtophoresis can be ttaced back over a century, as noted by Li (1). In 1800, Nicholson and Carlisle discovered electtolysis which is the decomposition of a compound into its ions by the passage of an electrical current through a solution of the compound (2). Soon thereafter, in 1808, Reuss (2) reported an interesting phenomenon involving electricity and its mobilizing effect on liquid matter. He used a U-shaped glass tube apparatus to demonsttate electtoosmosis, the movement of solvent in a field of applied potential. Two platinum wires were fused at the bottom of the tube. Powdered quartz was placed in the bottom between the wires. The tube was filled with water and a circuit was established. Soon after, hydrogen and oxygen gases were produced at the positive pole. Simultaneously, the water level rose at the negative pole and fell at the positive pole. Once the connection was broken, the water returned to its original position. This phenomenon was reproducible. The movement was not appreciable in systems that did not have the quartz powder in the bottom. Similar experiments led Reuss to propose a hypothesis that particles were ttansported from one pole to the other by galvanic current (2). This educed other experiments involving electricity as a cause of motion in fluids. In 1833, Faraday stated that the mass of a substance liberated from an electtolyte is proportional to the total quantity of electricity applied (2).



Capillary electrophoresis