Micellar electrokinetic capillary chromatography MECC/MEKC

The next important milestone in CE was achieved in 1984, when Terabe et al. described the method of micellar electrokinetic capillary chromatography (MECC or MEKC). By simply adding a surfactant to the separation buffer electrolyte, it was possible to separate both charged and neutral compounds simultaneously in CE. Erom this point on, the technique developed rapidly with many applications resulting in a demand for identification information. Coupling of CE to mass spectrometry was a next challenge and the... 

Micellar electrokinetic chromatography (MEKC) is a modality of liquid chromatography having a surfactant molecule in the form of a micelle, which was introduced by Terabe et al. in 1984 [38]. The formation and separation occur in the capillary and, hence, it is also called micellar electrokinetic capillary chromatography (MECC). This modality is useful for some specific molecules having solubilities in micelles and, therefore, utilized for the separation and identification of such compounds with great efficiency, reproducibility, and low levels of detections. The most commonly used compounds for micelle formation are sodium dodecyl sulfate (SDS), sodium tetradecyl sulfate, sodium decanesulfonate, sodium /V-lauryl-/V-mcthyllauratc, sodium... 

Micellar electrokinetic chromatography (MEKC) or micellar electrokinetic capillary chromatography (MECC)... 

The first reports of micellar electrokinetic capillary chromatography (MECC or MEKC) appeared in the literature in 1984 [16]. Through April 2002, there have been over 1100 English-language papers published in the field. The subject is covered in all general textbooks on capillary electrophoresis. While a vast number of surfactants and related reagents can be employed, most separations can be accomplished with a few simple recipes. 

Micelles and cyclodextrins are the most common reagents used for this technique. Micellar electrokinetic capillary chromatography (MECC or MEKC) is generally used for the separation of small molecules [6], Sodium dodecyl sulfate at concentrations from 20 to 150 mM in conjunction with 20 mM borate buffer (pH 9.3) or phosphate buffer (pH 7.0) represent the most common operating conditions. The mechanism of separation is related to reversed-phase liquid chromatography, at least for neutral solutes. Organic solvents such as 5-20% methanol or acetonitrile are useful to modify selectivity when there is too much retention in the system. Alternative surfactants such as bile salts (sodium cholate), cationic surfactants (cetyltrimethy-lammonium bromide), nonionic surfactants (poly-oxyethylene-23-lauryl ether), and alkyl glucosides can be used as well. 

There are numerous variations on free solution CE (FSCE), such as micellar electrokinetic capillary chromatography (MECC or MEKC), where a moving, pseudostationary phase is added to the CE buffer, and secondary chemical equilibria or interactions ensue that effect separations of even neutral compounds, as well as ionic analytes. However, in general, CE utilizes truly homogeneous, solution phase separation approaches, without a stationary (permanent, fixed) phase, making it perhaps ideally suited for molecular recognition in searching combinatorial libraries. 

MEKC instrumentation is not different from the apparatus used for capillary zone electrophoresis (chapter 3.3.2). The only deviation is that the run buffer contains micelles. MEKC is sometimes also referred to as micellar electrokinetic capillary chromatography (MECC). The signals are recorded as an electrokinetic chromatogram with signal intensity versus time. 

Micellar electrokinetic capillary chromatography (MECC or MEKC) Partitioning of solutes between micellar phase and solution phase Detergent added to buffer above critical micelle concentration Neutral molecules... 

Separation of neutral compounds using surfactant micelles this technique is called Micellar Electrokinetic Capillary Chromatography (MECC sometimes referred to as MEKC)... 

MECC, MEKC Micellar electrokinetic capillary chromatography... 

Micellar electrokinetic capillary chromatography (MEKC or MECC) is a more versatile technique than CZE due to its ability to separate neutral as well as ionic species. The term chromatography is used because a surfactant added to the buffer solution forms spherical aggregates of molecules... 

In order to separate neutral compounds, Terabe et al. [13] added surfactants to the buffer electrolyte. Above their critical micellar concentration (cmc), these surfactants form micelles in the aqueous solution of the buffer electrolyte. The technique is then called Micellar electrokinetic capillary chromatography, abbreviated as MECC or MEKC. Micelles are dynamic structures consisting of aggregates of surfactant molecules. They are highly hydrophobic in their inner structure and hydrophilic at the outer part. The micelles are usually... 

Here free solution indicates capillary electrophoresis carried out in a solution without any additives SDS-PAGE is sodium dodecyl sulfate-polyacrylamide gel electrophoresis MECC is micellar electrokinetic capillary chromatography, at times, also called MEKC (micellar electrokinetic chromatography). 

Micellar electrokinetic capillary chromatography (MEKC or MECC) is the mode employed for separating of neutral analytes by CE. In CZE, neutral molecules migrate together as one unresolved peak. MEKC can also improve resolution for cation and anion separations too. It normally utilises a bare fused silica capillary. The electrolyte contains micelles which have a polar, negatively charged exterior and a nonpolar interior. The... 

Most CE work so far has been done using the capillary zone electrophoresis (CZE) mode, where analytes are separated on the basis of differences in electrophoretic mobility, which is related to charge density. The separation is carried out in a capillary filled with a continuous background electrolyte (buffer). Micellar electrokinetic capillary chromatography (MEKC or MECC) is one other CE method based on differences in the interaction of the analytes with micelles present in the separation buffer, which can easily separate both charged and neutral solutes with either hydrophobic or hydrophilic properties. An alternative to MEKC is capillary... 

Abbreviations CZE capillary zone electrophoresis MECC or MEKC micellar electrokinetic chromatography CGE capillary gel electrophoresis CIEF capillary isoelectric focusing CEC capillary electrochromatography DAD Diode-array detection... 

The technique is therefore particularly suited to water-soluble species which possess a charge, which includes most dyes. Variations from the main technique (often referred to as capillary zone electrophoresis, CZE) do exist and these include the use of surfactants in the buffer to create micelles (often thought of as creating a pseudo-stationary phase inside the capillary) which then improve the separation of neutral species (and frequently charged molecules) owing to hydrophobic interactions. The term micellar electrokinetic chromatography (MECC or MEKC) is often used for CE separations carried out with the aid of a micellar buffer solution. 

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