Chromatography, micellar electrokinetic capillary

Micellar electrokinetic capillary chromatography (MECC) is a mode of CE similar to CZE, in which surfactants (micelles) are added to the buffer system. Micellar solutions can be used to solubilize hydrophobic compounds that would otherwise be insoluble in water. In MECC the micelles are used to provide a reversed-phase character to the separation mechanism. Although MECC was originally developed for the separation of neutral species by capillary electrophoresis, it has also been shown to enhance resolution in the analysis of a variety of charged species.16 

---

Micellar Electrokinetic Capillary Chromatography One limitation to CZE is its inability to separate neutral species. Micellar electrokinetic chromatography... 

Kovat s retention index (p. 575) liquid-solid adsorption chromatography (p. 590) longitudinal diffusion (p. 560) loop injector (p. 584) mass spectrum (p. 571) mass transfer (p. 561) micellar electrokinetic capillary chromatography (p. 606) micelle (p. 606) mobile phase (p. 546) normal-phase chromatography (p. 580) on-column injection (p. 568) open tubular column (p. 564) packed column (p. 564) peak capacity (p. 554)... 

The effects of pH on electrokinetic velocities in micellar electrokinetic chromatography was studied by using sodium dodecyl sulfate solutions [179]. Micellar electrokinetic capillary chromatography with a sodium dodecyl sulfate pseudostationary phase has been used to determine the partition constants for nitrophenols, thiazolylazo dyes, and metal chelate compounds [180]. A similar technique was used to separate hydroquinone and some of its ether derivatives. This analysis is suitable for the determination of hydroquinone in skin-toning creams [181]. The ingredients of antipyretic analgesic preparations have also been determined by this technique [182], The addition of sodium dodecyl sulfate improves the peak shapes and resolution in chiral separations by micellar electrokinetic chromatography [183]. 

Recently a new method was developed for the complete liquid chromatographic separation and diode array detection of standard mixtures of the 14 most frequently used synthetic colorants. Protocols for RP-HPLC - " and IP-HPLC techniques have been extensively described and the techniques were compared with micellar electrokinetic capillary chromatography, - which has been shown to be suitable for the analysis of synthetic colorants. 

Chou, S.S. et al., Determination of synthetic colors in soft drinks and confectioneries by micellar electrokinetic capillary chromatography, J Food ScL, 67, 1314, 2002. 

Thompson, C.O. and Trenerry, V.C., Determination of synthetic colours in confectionery by micellar electrokinetic capillary chromatography, J. Chromatogr. A, 704, 195, 1995. 

A., Testa, B. The relative partitioning of neutral and ionised compounds in sodium dodecyl sulfate micelles measured by micellar electrokinetic capillary chromatography. Eur. J. Pharm. Sci. 2002, 75, 225-234. 

Ferreres, F., Blazquez, M. A., Gil, M. L, and Tomas-Barberan, F. A. (1994a). Separation of honey flavonoids by micellar electrokinetic capillary chromatography. /. Chromatogr. A 669, 268-274. 

Saitoh, T., Hoshino, H., and Yotsuyanagi, T., Micellar electrokinetic capillary chromatography of porphinato chelates as a spectrophotometric approach to subfemtomole detection of metal chelates, Anal. Sci., 7, 495, 1991. 

Thormartn, W., Meier, R, Marcolli, C., and Binder, F., Analysis of barbiturates in human serum and urine by high-performance capillary electrophoresis-micellar electrokinetic capillary chromatography with on-column multiwavelength detection, /. Chromatogr., 545, 445, 1991. 

Clothier, Jr., J. G. and Tomellini, S. A., Chiral separation of veraprimil and related componds using micellar electrokinetic capillary chromatography with mixed micells of bile salt and polyoxyethylene ethers,. Chromatogr. A, 712, 179,1996. 

MECC, MEKC Micellar electrokinetic capillary chromatography... 

High-efficiency separations of FQ-labeled proteins are only achieved in the presence of an anionic surfactant, such as SDS. As a result, capillary isoelectric focusing is not useful for the analysis of these proteins. Instead, we employ capillary sieving electrophoresis and micellar electrokinetic capillary chromatography for our two-dimensional electrophoresis. 

Different separation mechanisms, which determine selectivity, can be exploited in HPCE by appropriate choice of operating conditions. There are four principal modes of operation (Table 4.22) and it should be noted that in only one, micellar electrokinetic capillary chromatography (MEKC), is it possible to separate neutral species from one another. 

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... 

Micellar electrokinetic capillary chromatography with photodiode array detection was used for the determination of polyaromatic hydrocarbons in soil [65]. A detection limit of lOpg and linear calibration over five orders were observed. Compared to a standard gas chromatographic analysis method, the miscellar electrokinetic chromatographic method is faster, has a higher mass sensitivity and requires smaller sample sizes. 

PANFILI G, MANZI P, COMPAGNONE D, SCARCIGLIA L and PALLESCHI G (2000), Rapid assay of chohne in foods using microwave hydrolysis and a choline biosensor , J Agric Food Chem, 48, 3403-7. pant I and trennery v c (1995), The determination of sorbic acid and benzoic acid in a variety of beverages and foods by micellar electrokinetic capillary chromatography , Food Chem, 53(2), 219-26. pare j r j and Belanger j m r (1997), Instrumental Methods in Food Analysis. Series Techniques and instrumentation in analytical chemistry - Vol. 18, Amsterdam, Elsevier. 

---