Capillary electrophoresis

The capillary electrophoresis English ( capillary electrophoresis : THIS ) can be used to separate from the ionic species according to their load and the forces from friction which are exerted on them.

In traditional electrophoresis, the electrically charged elements move in the conducting liquid under the influence of a Electric field. Introduced into the years 1960, the EC was conceived to separate from the chemical species according to their report/ratio cuts/load inside a small capillary tube filled with a electrolyte.

Instrumentation

Equipment necessary to carry out capillary electrophoreses is relatively simple (figure 1). The main components of the system are a bottle of sample, two bottles source and destination, a capillary, electrodes, a power source high voltage, a detector, and an apparatus of recovery and data processing.

The bottles source and destination as well as the capillary are filled with an electrolyte such as an aqueous solution with plug. To introduce the sample, the end of the capillary is placed in the bottle containing the sample, then is replaced in the bottle source (the sample is injected into the capillary by capillarity, pressure, siphoning or electro-injection).
La migration of the analytes is then set up thanks to an electric field applied between the bottles source and destination, and provided to the electrodes by the generator high voltage. All the ions, positive or negative, are attracted through the capillary in the same direction by flow electroosmotic (see further).

The analytes are separate during their migration because of their different electrophoretic mobilities (see further), and are detected near the exit of the capillary. The signal of the detector is sent to an apparatus which receives and treats these data, such as an integrator or a computer. The data are posted in the form of a électrophorégramme, which gives the answer of the detector according to time. The separate chemical compounds seem peaks with different times of retention on the électrophorégramme.

The resolution ( $R_s$ ) off capillary electrophoresis separations edge Be written ace:

$R_s = \ frac {1} {4} \ left (\ frac {\ triangle \ mu_p \ sqrt {NR}} {\ mu_p + \ mu_o} \ right)$

According to this equation, Maximum resolution is reached when the electrophoretic and electroosmotic mobilities are similar in Magnitude and opposite in sign. In addition, it edge Be seen that high resolution requires lower velocity and, correspondingly, increased analysis time.

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