MEKC: An update focusing on practical aspects

Abstract

This paper reviews recent methodological and instrumental advances in MEKC. Improvements in sensitivity arising from the use of on-line sample concentration (sweeping, stacking, and combination of both protocols) and derivatization (in-capillary reactions and coupling with flow-injection systems) and improvements in resolution obtained by changing the composition of the BGE (e.g., with organic modifiers, ionic liquids, nonionic and zwitterionic surfactants, mixed micelles, and vesicles) or using coated capillaries are discussed in detail. In addition, MS and LIF spectroscopy are examined in relation to their advantages and restrictions as applied to MEKC analysis. Some thoughts on potential future directions are also expressed.

Analytical Conditions and Separation Performance of Capillary Chromatography Based on the Tube Radial Distribution of Aqueous-Organic Mixture Carrier Solvents under Laminar-Flow Conditions

“…Various capillary chromatography techniques, including capillary electrochromatography, 1,2 micellar electrokinetic capillary chromatography, 3,4 and high-performance liquid capillary chromatography using packed and monolithic columns, [5][6][7] have been investigated as powerful separation tools. Naturally, they require specific treatments or procedures, such as applying a high voltage, the addition of additives (gels, surfactants, etc.…”

Determination of organic acids by CE and CEC methods

“…This chromatographic portion of the separation mechanism can either be introduced by the addition of a pseudo-stationary phase to the carrier electrolyte, like in MEKC and microemulsion EKC (MEEKC), or by the use of a true stationary phase as done in CEC. Focusing on the separation of organic acids, MEKC and MEEKC are primarily employed for the separation of less hydrophilic acids such as species with more complex structures (often extracted from natural products) or derivatized amino acids (AAs) [12,13]. CEC, either using fully packed or wall-coated open tubular (OT) columns, offers the possibility to combine electrophoretic with ion-exchange chromatographic separation mechanisms [14].…”

Use of SDS micelles for improving sensitivity, resolution, and speed in the analysis of β‐lactam antibiotics in environmental waters by SPE and CE

“…Despite the occasional use of Cy5 for labeling primary amine groups-containing analytes in CE-LIF [33], the experimental procedure for carrying out the derivatization process is relatively well established. Thus, the same experimental conditions as those reported earlier for other amino compounds [34,35] were obtained for the kinetics of the labeling reaction (257C and 30 min) and for the optimum concentration of the label (concretely 40 mM).…”