Electrophoretic micro total analysis

Stanislawski, B., Kaniansky, D., Masar, M., Johnck, M., Design principles, performance and perspectives of a complete miniaturized electrophoretic instrument. Micro Total Analysis Systems Proceedings jlTAS 2002, symposium, 6th, Nara, Japan, Nov. 3-7, 2002, 2000, 350-352. 

Reshni, K.A., Morris, M.D., Johnson, B.N., Bums, M.A., On-line detection of electrophoretic separations on a microchip by Raman spectroscopy. Micro Total Analysis Systems 98, Proceedings pi AS 98 Workshop, Banff, Canada, 13-16 Oct. 1998, 109-112. 

Capillary electrophoresis systems were the first micro total analysis systems and emerged as single chip solutions from the analytical chemistry field in the 1990s [254]. Several companies utilize microfluidic capillary electrophoretic chips for chemical analysis, with capillaries of typically 10-100 pm diameter [255]. 

Electrophoretic separation of small charged species was one of the earliest applications of lab-on-a-chip and microfluidics. Indeed, the paper [7] that introduced the term pTAS (micro-total analysis system) dealt primarily with the electric field hmits imposed by Joule heating. Microfiuidic electrophoresis leads to tremendous gains in the separation time and strongly reduces the amount of sample consumed on chip. 

An entirely different concept in analytical separations is provided by capillary electrophoresis (CE) in which the flow of liquid is generated by electro-osmotic flow (EOF) driven by an external electric field. The major advantage of this approach is the essentiaUy flat plug flow profile that leads to intrinsically more narrow elution peaks than the parabolic flow profiles characteristic of pressure-driven viscous flows. In capillary zone electrophoresis (CZE) separation is achieved by superimposing the different electrophoretic mobihties of the solutes on to the EOF. In electrochromatography the separation is achieved as in packed column HPLC but using an EOF to generate flow of the mobile phase past the stationary phase particles. The importance of these EOF-based techniques is their application to miniaturized devices, lah-on-a-chip or micro total analysis systems. Such devices that can be directly interfaced to a mass spectrometer via an ESI source are currently under intense development. 

Capillary electrophoresis (CE) is a micro-column separation technique that can separate target analytes on the basis of differences in electrophoretic mobilities via the application of high electric fields (several hundreds of V cm O. It has been shown to be a very powerful instrumental technique, resulting in fast, highly efficient separation and analysis of complex liquid-phase mixtures [l]. Moreover, the fabrication of micro-total analysis systems (p,-TAS) involving CE has recently made substantial progress [2,3]. Several detection methods have been successfully introduced to CE analysis, which are absorption and fluorescence spectroscopy, electrochemistry, and more recently, mass spectrometry. 

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