Capillary
electrophoresis chromatography(CEC) is the newest instrument and is used
primarily for teaching. Capillary Electrophoresis (CE) and Capillary
Electrochromatography (CEC) are both modern analytical techniques which
have been developed in recent years and have been applied to a wide range
of application areas. Thousands of instruments are now in use for the
analysis of pharmaceuticals, DNA, proteins, peptides, clinical and
forensic samples, agrochemicals, fine chemicals and natural products.
It has high efficiency and resolution, rapid analysis time,
plus minimal sample and solvent requirements, is an established technique
in many laboratories. Its flexibility covers a broad range of applications
in a wide variety of industries, from drug discovery and development
through quality control and ion analysis. Agilent Technologies (formerly
H-P) pioneered the development of this technique with the Agilent
Capillary Electrophoresis system. Innovations include diode array
detection in CE, the extended light-path capillaries, automated fraction
collection, capillary electrochromatography (CEC), the high sensitivity
detection cell, and a fully integrated way to use CE-MS.
Capillary electrochromatography (CEC) is a rapidly evolving hybrid technique between HPLC and CE. In essence CE capillaries are packed with HPLC packing and a voltage is applied across the packed capillary which generates an electro-osmotic flow (EOF) [for example of EOF see the CE theory page of this website). The EOF transports solutes along the capillary towards the detector. Both differential partitioning and electrophoretic migration of the solutes occurs during their transportation towards the detector which leads to CEC separations. It is therefore possible to obtain unique separation selectivities using CEC compared to both HPLC and CE. The beneficial flow profile of EOF reduces flow related band broadening and separation efficiencies of several hundred thousand plates per meter are often obtained in CEC. There is no back pressure when EOF occurs so small particle sizes such as 1-3 micron can be used to improve separation efficiencies. Generally, carrier electrolytes containing high levels (40-80%) of organic solvents such as methanol or acetonitrile are employed in CEC which means it is useful for water-insoluble compounds which can be difficult to analyze by CE. The instrument used in CEC is identical to that used in CE - see below except that a packed capillary is used.
