Capillary array instruments

Unimicro Technologies Trisep-100 (Pleasanton, CA) Capillary array instrumentation CEC, pLC, CZE Gradient elution, several detectors... 

FIGURE 3 A schematic of a 96-capillary array instrument. The picture is courtesy of Combisep (Ames, lA). 

Figure 2 (A) Design of a capillary array instrument with two-point detection and...

Fig. 22 Representative pictures of biomolecules separated by slab gel electrophoresis (past) and a capillary array instrumentation (present). (Courtesy of SpectruMedix.)...

In a different approach a super-high-throughput ee-assay was developed on the basis of chirally modified capillary array electrophoresis (CAE).90 CAE was used in the Human Genome Project, and commercially available instruments have been developed which comprise a high number of capillaries in parallel, for example the 96-capillary unit MegaBACE consisting of 6 bundles of 16 capillaries.91 The system can address a 96-well microtiter plate. It was adapted to perform ee-determinations of chiral amines, which are potentially accessible by catalytic reductive amination of ketones, transition metal catalyzed Markovnikov addition of ammonia, or enzymatic hydrolysis of acetamides (Scheme 14).90... 

Capillary gel electrophoresis (CGE) with polymer solutions is about 8 to 10 times faster than slab gel electrophoresis. However, the single-lane nature of CE was unable to compete in throughput with slab gel instruments, which are run in parallel. This led to the development of capillary array electrophoresis (CAE) [38] in 1992. As the name suggests, electrophoresis is performed in an array of capillaries to run multiple samples in parallel. Figure 8.20 shows a microfabricated capillary array system [39] on a glass wafer consisting of 96 channels. 

In traditional analytical chemistry the determination of enantiomeric purity is sometimes carried out by capillary electrophoresis (CE) in which the electrolyte contains chiral selectors such as cyclodextrin (CD) derivatives [54], Unfortunately the conventional form of this analytical technique allows only a few dozen ee determinations per day. However, as a consequence of the analytical demands arising from the Human Genome Project, CE has been revolutionized in recent years so that efficient techniques for instrumental miniaturization are now available, making ultra-high-through-put analysis of biomolecules possible for the first time [55]. Two different approaches have emerged, namely capillary array electrophoresis (CAE) [55a - e] and CE on microchips (also called CAE on chips) [55f - m[. Both techniques can be used to carry out... 

Capillary electrophoresis can be also applied for DNA sequencing. For this purpose, multicapillary (array) instruments with laser-induced fluorescence detection are being developed. Detailed descriptions of these methods is beyond the scope of this entry. 

A major goal of the human genome project is to determine the order of occurrence of the four bases, adenine (A), cytosine (C), guanine (G), and thymine (T), in DNA molecules. The sequence defines an individual s genetic code. The need for sequencing DNA has spawned the development of several new analytical instruments. Among the most attractive of these approaches is capillary array electrophoresis. In this technique, as many as 96 capillaries are operated in parallel. The capillaries are filled with a separation matrix, normally a linear polyacrylamide gel. The capillaries have inner diameters of 35 to 75 p,m and are 30 to 60 cm in length. 

The capillary format of SFC is attractive because of the potential of interfacing with a wide array of detectors available when carbon dioxide is used as the mobile phase. Several advances, beyond the issue of mobile-phase polarity, are, however, required prior to the technique becoming viable for pharmaceutical analyses. Capillary SFC instrumentation has lacked the requisite analytical performance for pharmaceutical analyses, and difficulties are encountered due to the acidic nature of fused silica and the problem of measuring impurities while, at the same time, not overloading the stationary phase with the main component. ... 

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