Capillary electrophoresis peak capacity

This book is organized into five sections (1) Theory, (2) Columns, Instrumentation, and Methods, (3) Life Science Applications, (4) Multidimensional Separations Using Capillary Electrophoresis, and (5) Industrial Applications. The first section covers theoretical topics including a theory overview chapter (Chapter 2), which deals with peak capacity, resolution, sampling, peak overlap, and other issues that have evolved the present level of understanding of multidimensional separation science. Two issues, however, are presented in more detail, and these are the effects of correlation on peak capacity (Chapter 3) and the use of sophisticated Fourier analysis methods for component estimation (Chapter 4). Chapter 11 also discusses a new approach to evaluating correlation and peak capacity. 

With capillary electrophoresis (CE), another modern primarily analytically oriented separation methodology has recently found its way into routine and research laboratories of the pharmaceutical industries. As the most beneficial characteristics over HPLC separations the extremely high efficiency leading to enhanced peak capacities and often better detectability of minor impurities, complementary selectivity profiles to HPLC due to a different separation mechanism as well as the capability to perform separations faster than by HPLC are frequently encountered as the most prominent advantages. On the negative side, there have to be mentioned detection sensitivity limitations due to the short path length of on-capillary UV detection, less robust methods, and occasionally problems with run-to-run repeatability. Nevertheless, CE assays have now been adopted by industrial labs as well and this holds in particular for enantiomer separations of chiral pharmaceuticals. While native cyclodextrins and their derivatives, respectively, are commonly employed as chiral additives to the BGEs to create mobility differences for the distinct enantiomers in the electric field, it could be demonstrated that cinchona alkaloids [128-130] and in particular their derivatives are applicable selectors for CE enantiomer separation of chiral acids [19,66,119,131-136]. 

This chapter illustrates possible applications of capillary electrophoresis in impurity profiling. Due to the large peak capacity of the technique, it is extremely well suited to separate the main drug compound from its possible impurities that often have a very related chemical structure. Moreover, the high efficiencies obtained, as well as the low reagent consumption make it a viable alternative to liquid chromatography in many cases of drug analysis. 

A new topic is now included Chapter 20 about quahty assurance. Part of it could be found before in chapter 19 but now the subject is presented much broadly and independent of Analytical HPLC . Two chapters in the appendix were updated and expanded by Bruno E. Lendi, namely the ones about the instrument test (now chapter 25) and troubleshooting (now chapter 26). Some new sections were created 1.7, comparison of HPLC with capillary electrophoresis 2.11, how to obtain peak capacity 8.7, van Deemter curves and other coherences 11.3, hydrophilic interaction chromatography 17.2, method transfer 18.4, comprehensive two-dimensional HPLC 23.3, fast separations at 1000 bar 23.5, HPLC with superheated water. In addition, many details were improved and numerous references added. 

Shadpour et al. [81] and Osiri et al. [82] employed SDS micro-capillary gel electrophoresis (SDS p-CGE) and micellar electrokinetic capillary (MEKC) electrophoresis in the first and second dimensions, respectively, to sort intact proteins using a poly (methylmethacrylate), PMMA, microchip. A diagram of the microchip is shown in Fig. 4. The electrophoresis commenced in the first dimension for a prescribed amount of time and, then, the bands from the first dimension were sequentially injected into the second dimension for development. The 2D electrophoresis system could generate a peak capacity of 2,600 for proteins isolated from fetal calf serum (see Fig. 4). 

The rapid separations offered by capillary electrophoresis have made it amenable as a detector in hyphenated techniques. For LC-CE, the total analysis time is usually governed by the LC separation, which generally takes minutes. However, capillary electrophoresis detection adds more peak capacity because of a second and orthogonal dimension for separation, and shorter separation conditions for LC can often be tolerated. For example, a 2.5 min reversed-phase liquid chromatography gradient was used in conjunction with 2.5 s CE separations for the detection of a tryptic digest of cytochrome c. ... 

Resolution in capillary gel electrophoresis of DNA sequencing was shown to be directly proportional to the product of the number of bases and the relative peak distance, i.e., to the mean separation of peaks.43 Reformulation of the treatment of the capacity factor has been used to simplify and clarify the interpretation of the separation factor in electrophoresis.44 Peak... 

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