Electrophoresis micellar electrokinetic

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. 

Michels, D.A., Hu, S., Damhrowitz, K.A., Eggertson, M.J., Lauterhach, K., Dovichi, NJ. (2004). Capillary sieving electrophoresis-micellar electrokinetic chromatography fully automated two-dimensional capillary electrophoresis analysis of Deinococcus radiodurans protein homogenate. Electrophoresis 25, 3098-3105. 

Bendahl, L., Hansen, S. H., and Gammelgaard, B. (2001). Capillary modified by noncovalent anionic polymer adsorption for the capillary zone electrophoresis, micellar electrokinetic capillary chromatography and capillary electrophoresis mass spectrometry. Electrophoresis 22, 2565-2573. 

After a short introduction into the relevance of Impurity profiling for regulatory authorities, public health, and the pharmaceutical industry, an overview is presented based on the various modes of capillary electrophoresis that have been used in drug impurity analysis. The applications of capillary zone electrophoresis, non-aqueous capillary electrophoresis, micellar electrokinetic capillary chromatography, microemulsion electrokinetic capillary chromatography, capillary gel electrophoresis, and capillary electrochromatography are presented consecutively. 

Currently, there are five major modes of operation of CE capillary zone electrophoresis (CZE), also referred to as free solution or free flow capillary electrophoresis micellar electrokinetic chromatography (MEKC) capillary gel electrophoresis (CGE) capillary isoelectric focusing (CIEF) and capillary isotachophoresis (CITP). Of these, the most commonly utilized capillary techniques are CZE and MEKC (Rabel and Stobaugh 1993 Issaq 1999 Smyth and McClean 1998). 

The early phase of development can be characterized by a transfer of concepts from conventional CE to the planar format, such as capillary gel electrophoresis, micellar electrokinetic chromatography, sample stacking and pre- and postcolumn sample derivatization. Emphasis was laid on the demonstration of the specific advantages mainly from the separation science point of view. With only very few exceptions, detection has received much less attention yet. LIF detection with confocal imaging has been used in most of the early work owing to its high sensitivity and its relatively easy implementation. If not explicitly mentioned otherwise, all experiments described in the following sections were carried out with LIF detection [28,29]. 

The separation scientist with experience gained from a LC background may tend to limit the modes of electrochromatography to reversed phase (RP), normal phase, ion-exchange and, maybe, size-exclusion. Analysts from an electrophoretic background typically use the term "CE" in a much broader sense to include the main modes of capillary zone electrophoresis, micellar electrokinetic chromatography, capillary gel electrophoresis, isoelectric focusing and isotachophoresis. 

Hu, S., Michels, D.A., Abu Fazal, M., Ratisoontom, Ch., Cunningham, M.L. and Dovichi, N.J. (2004) Capillary sieving electrophoresis/micellar electrokinetic capillary chromatography for two-dimensional protein fingerprinting of single mammalian cells. Anal. Chem. 76, 4044-4049. 

Keywords Capillary electrophoresis Micellar electrokinetic chromatography Microchip pTAS Nonaqueous capillary electrophoresis How injection analysis Solid-phase microextraction Bipolar electrochemical swimmers... 

Capillary electrophoresis (micellar electrokinetic chromatography MEKC) has also proven to be an effective method for the analysis of caffeic acid derivatives [44]. The method provides an excellent resolution and a very high sensitivity and enables the discrimination of the species (see Fig. 5). 

Meier, P. Thormann, W. Determination of thiopental in human serum and plasma by high-performance capillary electrophoresis-micellar electrokinetic chromatography. J. Chromatogr. 1991, 559, 505-513. 

The last set of experiments provides examples of the application of capillary electrophoresis. These experiments encompass a variety of different types of samples and include examples of capillary zone electrophoresis and micellar electrokinetic chromatography. 

WORTH c c, wiESSLER M and SCHMITZ o J (2000) Analysis of catechins and caffeine in tea extracts by micellar electrokinetic chromatography . Electrophoresis, 21 (17), 3634-... 

Capillary electrophoresis is increasingly used in food analysis due to its separation performance combined with the short time of analysis. - CapiUary electrophoresis recently applied to colorant measurements includes technical variants such as capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography. ... 

S. L, Carlucci, A., Bregni, C., Kenndler, E. Comparison of the retention charaderi sties of different pseudostationary phases for microemulsion and micellar electrokinetic chromatography of betamethasone and derivatives. Electrophoresis 2003, 24, 984-991. 

A variety of formats and options for different types of applications are possible in CE, such as micellar electrokinetic chromatography (MEKC), isotachophoresis (ITP), and capillary gel electrophoresis (CGE). The main applications for CE concern biochemical applications, but CE can also be useful in pesticide methods. The main problem with CE for residue analysis of small molecules has been the low sensitivity of detection in the narrow capillary used in the separation. With the development of extended detection pathlengths and special optics, absorbance detection can give reasonably low detection limits in clean samples. However, complex samples can be very difficult to analyze using capillary electrophoresis/ultraviolet detection (CE/UV). CE with laser-induced fluorescence detection can provide an extraordinarily low LOQ, but the analytes must be fluorescent with excitation peaks at common laser wavelengths for this approach to work. Derivatization of the analytes with appropriate fluorescent labels may be possible, as is done in biochemical applications, but pesticide analysis has not been such an important application to utilize such an approach. 

Nishi, H. and Terabe, S., Application of micellar electrokinetic chromatography to pharmaceutical analysis, Electrophoresis, 11, 691, 1990. 

For many applications, diode array detection has become routine. A photodiode array was used for simultaneous detection of 100 capillaries in zone electrophoresis and micellar electrokinetic chromatography (MEKC).1516 Deflection of a laser beam by acoustic waves was reported as a means to scan six capillary channels on a microchip.17 The design of a low-noise amperometric detector for capillary electrophoresis has been reported.18... 

Xue, G., Pang H.-M., and Yeung E.S., Multiplexed capillary zone electrophoresis and micellar electrokinetic chromatography with internal standardization, Anal. Chem. 71, 2642, 1999. 

FIGURE 15.1 One-dimensional capillary electrophoresis separation of a protein homogenate prepared from the hTERT cell line. Both separations were preformed in 30 pm ID, 145 pm OD, 20 cm long capillaries at 20,000 V. (a) Micellar electrokinetic chromatography performed with a 100 mM CHES, 100 mM Tris, and 15 mM SDS buffer at pH 8.7. Sample is electro-kinetically injected with 0.25 kV for 1 s (b) Capillary sieving electrophoresis performed in 5% Dextran (513 kDa), 100 mM CHES, 100 mM Tris, 3.5 mM SDS, pH 8.7. 

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. 

Solinova V, Kasicka V, Koval D et al (2004) Analysis of synthetic derivatives of peptide hormones by capillary zone electrophoresis and micellar electrokinetic chromatography with ultraviolet-absorption and laser-induced fluorescence detection. J Chromatogr B 808 75-82... 

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