Introduction of capillary electromigration separation techniques

- Capillary separation technique is the branch of separation methods. The column used in this method is the type of coated or packed capillary columns, and the mobile phase is an electrolyte solution. The electric field is applied, which causes Electro-osmosis and Electrophoresis occurred in the mobile phase during a sample is introduced. The system in this method is the same as any other chromatographic system with minor modification.

- The applied electric field generates heat during separation process. This brings about ''Thermal effects'', are the main reason for band broadening in Capillary separation technique.

- 1940s-1950s paper and gels coating on the column are used to minimized thermal effects. Convective transport(occur the movement of mobile phase in electric field ) was prevented. Gels make it possible for size separation with high surface areas without causing the radial temperature gradient, and the high field strengths can be used for fast separation.

- 1990, The capillary electro migration techniques reach a reasonable level of maturity. Thin layer gels electrophoresis had been developed. Although its lack of complete automation, time-consuming, labor-intensive methods, slow separation, and qualitative detection procedures are disadvantages, it still continues to develops because of low cost, standardization, superior resolution and good sensitivity.

- Capillary-electro-migration separation techniques, what will be discuss is a distortion of general use of electrophoretic techniques. The disadvantages are poor injection precision and concentration sensitivity, poor retention reproducibility, matrix interference.

- Classification: column chemistry and common applications:

CE(Capillary Electrophoresis) describes the separation of ions in an electric fields based on differences in electrophoretic mobility of electrolyte solutions. Inorganic and organic ions, ionizable compounds, zwitterions, and biopolymers are separated by CE

CZE(Capillary Zone Electrophoresis)

MEKC or MECC(Micellar Electrokinetic Chromatography) describes separations based on a combination of electrophoresis and two-phase distribution of analytes between that electrolytes solution and a secondary micellar phase. Water soluble neutral compounds, weak acid and bases are separated by MECC

MEEKC or MEECC(MicroElulsion Electrokinetic Chromatography) is similar to MEKC excepts that it is used in place of micellar secondary phase.

CEC(Capillary ElectroChromatography) the mobile phase is driven by electroomosis through a packed or wall-coated column, possibly assisted by pressure.

CSE(Capillary Sieving Electrophoresis) the separation is based on size and shape differences, this is caused by migration through capillary column filled with gels matrix.

CGE(Capillary Gel Electrophoresis) is used as CSE and to separate macromolecules.

CIEF(Capillary IsoelEctric Focusing) is an electrophoretic techniques used to separate amphoretic analtyes such as proteins and other zwitterionic compounds

CITP(Capillary Isoachophoresis) is an electrophoretic technique based on electrophoretic mobility in an discontinuous buffer system.