MEEKC chromatography

MEEKC Microemulsion electrokinetic chromatography TFA Target factor analysis... 

The reason for this is that if a stable, optically transparent emulsion is to be obtained, the relationship between the amount of the oil phase and the surfactants has to be within a relatively narrow range. Microemulsion elec-trokinetic chromatography has been shown to be a highly applicable technique for the analysis of complex mixtures such as multicomponent formulations and drug-related impurities. This technique opens a new way to determine water-insoluble neutral species such as steroids, which are difficult to analyze by CE. It is therefore likely that the MEEKC method will be increasingly applied for pharmaceutical and biopharmaceutical analyses in coming years. 

As in chromatography, the retention factor (k ) in MEEKC is defined as the ratio of the number of moles of the solute in the micellar pseudostationary... 

Microemulsion electrokinetic chromatography, MEEKC (or MECC), is a relatively new technique which holds some promise of delivering octanol/water partition coefficients much more conveniently than the shake-flask method (Gluck, 1996 Ishihama, 1994). MEEKC is claimed to have all the advantages of an HPLC method but it is not suitable for solutes with pKas much below 7.0 (Adlard, 1995). It has been used over a log P range of -1.0 to +4.0. 

Microemulsion electrokinetic chromatography (MEEKC) or microemulsion electrokinetic capillary chromatography (MEECC) — A special case of - electrokinetic chromatography, where a microemulsion is employed as the dispersed phase. 

Please note that I have not covered the whole of MECC. One notable omission involves the use of surfactants that generate in-situ charge [28]. Another related omission is microemulsion electrokinetic capillary chromatography (MEEKC) [29]. I have not had the opportunity or the need to try these systems. 

Electrokinetic methods capillary electrophoresis (CE), micellar electrokinetic chromatography (MEKC), microemulsion electrokinetic chromatography (MEEKC), capillary electrochromatography (CEC)... 

MICROEMULSION ELECTROKINETIC CHROMATOGRAPHY (MEEKC) FOR NEUTRAL AND/OR CHARGED DRUGS... 

Different types of EKC have been developed. Cy-clodextrins (CDEKC) have been used to form inclusion complexes with solutes to effect their separation. Other examples of EKC include microemulsion electrokinetic chromatography (MEEKC). The MEKC technique (for a detailed treatise, the reader is referred to Ref. 4) utilizes the presence of micelles in the electrolyte buffer solution to influence the migration time of solutes. In this case, the separation carrier is the micelle [5]. 

To date, the use of chemometrics for method development and robustness testing has been published for all areas of CE, including capillary zone electrophoresis (CZE), capillary electrokinetic chromatography (EKC) using chiral selectors for enantioseparations, micellar electrokinetic chromatography (MEKC), and microemulsion electrokinetic chromatography (MEEKC). A comprehensive description can be found in Chapters 5 and 13 as well as in recent reviews (6-11). Several monographs on chemometrics in analytical chemistry have been published such as References 12-14. This chapter will... 

Capillary electrophoresis (CE) is an emerging analytical technique for determination of catechins. The majority of CE studies involve the analysis of catechins in tea infusion, extracts as well as supplements. The three variants of CE suitable for the analysis of catechins include capillary zone electrophoresis (CZE), micellar electro-kinetic chromatography (MEKC), and microemulsion electrokinetic chromatography (MEEKC) with UV detection. In general, the resolution of MEKC was found to be superior to CZE for separation of catechins. MEEKC is a relatively new technique, and the few reports available suggest that it offers a performance similar to MEKC. CE conditions are often quite complex, and many factors, such as buffer composition, pH, presence of surfactants, and column temperature, can all affect the quality of separation and should be optimized individually. On the other hand, CE offers several advantages over HPLC. The short analysis time (<20 minutes), low running costs, and reduced use of solvents make it an attractive alternative for routine analysis of catechins. 

Several modes of CE have been described in the literature over past decade [6, 7], The most common are open tubular or capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), microemulsion elec-trokinetic chromatography (MEEKC), capillary electrochromatograpy (CEC), capillary gel electrophoresis, capillary isoelectric focusing and capillary iso-tachophoresis. Three recent reviews by Watzig [113], Tagliaro etal. [114] and Riekkola etal. [115] summarise the current method development options available to manipulate selectivity. In pharmaceutical analysis, CZE, MEKC, MEEKC and CEC are commonly used. 

Minimizing the temperature effects discussed above could be obtained with the use of polymer micelles or polymer surfactants [81-83], whose CMC is zero, and even in nonaqueous solvent, the micelle is stable. Although several polymer surfactants are commercially available, no such surfactant is widely accepted, probably because SDS, CTAB, or CTAC, and bile salts are superior to polymer surfactants as the pseudostationary phase in MEKC. Although microemulsion electrokinetic chromatography (MEEKC) is not discussed in this chapter but covered in Chapter 4 by Altria and colleagues, a similar optimization strategy to that in MEKC applies to MEEKC [84-86]. Since... 

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