It is well known that the resolving power of capillary zone electrophoretic separations may be improved with an increase in the applied electric field strength and separation time. While large electric fields may be realized in short analysis channels commonly employed in microfluidic systems, this experimental design is not suitable for achieving long separation times. In this chapter, we describe the use of a steady and/or a periodic pressure-driven backflow to increase the separation time in short microchannels thereby enabling the analysis of closely related species on microchip devices. The reported backflow was realized in our assays using an on-chip pressure-generation capability that relied on the partial blockage of electroosmotic flow around a junction of two glass channel segments having different depths. Although the noted strategy led to additional band broadening in the system, the resolving power of our device was observed to substantially improve upon introduction of the reported steady/periodic pressure-driven backflow for analysis channels shallower than 5 μm.
Band broadening Capillary zone electrophoresis Electroosmosis Microfluidic pump Pressure-driven backflow
This is a preview of subscription content, log in to check access.
Springer Nature is developing a new tool to find and evaluate Protocols. Learn more
Taylor GI (1953) Dispersion of soluble matter in solvent flowing slowly through a tube. Proc R Soc (London) 219:186–203CrossRefGoogle Scholar
Henley TH, Wilburn RT, Crouch AM, Jorgenson JW (2005) Flow counterbalanced capillary electrophoresis using packed capillary columns: resolution of enantiomers and isotopomers. Anal Chem 77:7024–7031CrossRefGoogle Scholar
Yanagisawa N, Dutta D (2010) Pressure generation at the junction of two microchannels with different depths. Electrophoresis 31:2080–2088CrossRefGoogle Scholar
Fu JL, Fang Q, Zhang T, Jin XH, Fang ZL (2006) Laser-induced fluorescence detection system for microfluidic chips based on an orthogonal optical arrangement. Anal Chem 78:3827–3834CrossRefGoogle Scholar