Charged species, separation using

For nonionized compounds, or to change selectivity for ionized compounds, buffer additives such as micellar sodium dodecyl sulfate (SDS) or an octane/ butan-l-ol/SDS microemulsion may be used. For nonionic compounds, separation is based on distribution between the buffer and the charged additive, which moves at a different velocity than the background electrolyte. For charged species, separation is based on both the partitioning and the electrophoretic mobility of the sample components. Samples that are not soluble in aqueous media may be separated in organic solvents such as methanol or acetonitrile containing a conductive salt. ... 

Capillary zone electrophoresis provides effective separations of any charged species, including inorganic anions and cations, organic acids and amines, and large biomolecules such as proteins. For example, CZE has been used to separate a mixture of 36 inorganic and organic ions in less than 3 minutes.Neutral species, of course, cannot be separated. 

The concept of using a time delay to separate charged species in space is also employed in ZEKE-PES and MATI, Chap. 2.10.3.)... 

Micellar electrokinetic capillary chromatography (MECC), in contrast to capillary electrophoresis (CE) and capillary zone electrophoresis (CZE), is useful for the separation of neutral and partially charged species [266,267]. In MECC, a surfactant, usually sodium dodecyl sulfate (SDS), is added to the buffer solution above its critical micellar concentration to form micelles. Although SDS is certainly the most popular anionic surfactant in MECC, other surfactants such as bile salts have proved to be very effective in separating nonpolar analytes that could not be resolved using SDS [268]. 

The migration of charged species under the influence of an externally applied electric field is known as electrophoresis. Differences in the mobility of the analytes due to their average charge, size, shape, and properties of the used electrolyte solution form a basis of a valuable separation method in chemistry. 

Following the above, we address some of the experimental aspects of electrophoresis. In this context, a few other forms of electrophoresis (e.g., moving boundary electrophoresis and zone electrophoresis) are described briefly. The last of these is used when separation of charged species, rather than the measurement of mobilities, is the item of interest (Section 12.9). 

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