Capillary electrophoresis polymer optimization

Tian H, Brody LC, Mao D, Landers JP. Effective capillary electrophoresis-based heteroduplex analysis through optimization of surface coating and polymer networks. Anal Chem 2000 72 5483-5492. 

The combination of XRF with electrophoresis can constitute a quasi-on-line coupling technique. Great efforts have been made to develop on-line analysis techniques with XRF. Mann et reported a technique of on-line SRXRF detection of metal ions, such as Fe, Co, Cu, and Zn, in their high binding-constant complexes for capillary electrophoresis (CE) separation. An X-ray transparent polymer coupling is used to create a window for the on-line X-ray detection. In contrast to ICP-MS, this detection technique is not limited by sample or the buffer volatility or atomization efficiency. Simultaneous XRF and UV absorbance detection can be used to provide on-line determination of metal/chelate ratios. A bench-top energy-dispersive micro X-ray fluorescence system was also combined with the CE apparatus constructed by a thin-walled fused-silica capillary for elemental analysis of the species containing Fe, Co, and Cu, for example. This coupled technique used for metalloprotein speciation analysis can avoid the compromise between optimal separation and sensitive detection, which must be taken into account in the HPLC-ICP-MS procedure. In addition, this detection scheme is non-destructive, so the separated material can be recovered for additional characterization. 

Table 1 summarizes several of the experimental methods discussed in this chapter. A need exists for new or revised methods for transport experimentation, particularly for therapeutic proteins or peptides in polymeric systems. An important criterion for the new or revised methods includes in situ sampling using micro techniques which simultaneously sample, separate, and analyze the sample. For example, capillary zone electrophoresis provides a micro technique with high separation resolution and the potential to measure the mobilities and diffusion coefficients of the diffusant in the presence of a polymer. Combining the separation and analytical components adds considerable power and versatility to the method. In addition, up-to-date separation instrumentation is computer-driven, so that methods development is optimized, data are acquired according to a predetermined program, and data analysis is facilitated. 

We hope that this brief review has given the reader a general feeling of the development and application of CE in the separation of nucleic acids. With the advent of capillary array electrophoresis and microchip electrophoresis, as well as remarkable improvements in separation matrices, CE has become a standardized and cost-effective technique in the separation of nucleic acids. Novel thermo-responsive polymer solutions combine the merits of different monomers, and offer the possibility to fine-tune the desirable properties of polymer molecular architecture and chemical composition. Artificial entropic trapping systems obviate the use of viscous polymer solutions, and even offer fast, unattended, miniaturized, and multiplexed platforms. Optimizing the geometry of these electrophoretic systems to both increase the separation and reduce the diffusion (band broadening) is the main topic for future research. 

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