Field gradient electrophoresis

Abstract

The class of equilibrium gradient methods utilizes the opposition of two forces, at least one of which changes in magnitude with position, to separate and concentrate analytes. The drawback of many methods of this type is that the production of two opposing forces requires in comparison to standard methods, such as capillary electrophoresis, a relatively complex apparatus. In addition, for techniques such as electric field gradient focusing, hydrodynamic flow leads to Taylor dispersion, which limits the attainable concentration factor. We propose a new method, gradient field electrophoresis, which achieves analyte separation and focusing with only one spatially varying force, an electric field gradient. A model for the method is developed and used to analyze peak capacity. Experimental results for a protein (R-phycoerythrin) are given and compared to the model.

Characterization of voltage degradation in dynamic field gradient focusing

“…Recently, interest in EFGF has increased with the focus of research being placed on the development of systems that use alternative methods to generate the electric field gradient (for reviews see [15,[18][19][20]). Some of the major advances have been: (i) the use of dialysis membranes to form a conductivity gradient which gives rise to an electric field gradient [21][22][23], (ii) the use of shaped, ionically conductive polymers [24], (iii) the use of buffers with temperature dependent ionic strengths [25], and (iv) the use of a computer-controlled electrode array to generate the electric field gradient [26][27][28].…”

Counter‐flow gradient electrofocusing

“…Tolley et al and Warnick et al [36,37] performed exhaustive theoretical descriptions of EFGF, and Humble et al [38] put the theory into practice using a microdevice employing a shaped ionically conductive membrane. The membrane acted similar to Koegler and Ivory's initial demonstration by shaping the electric field through cross-sectional area variations.…”

“…Second, the peaks do not migrate along the length of the column, but asymptotically focus into peaks localized at the zero-velocity points. Assuming a linear velocity gradient, the focused peaks will be Gaussian with a center and width that both decay exponentially to their steady-state values [37,62]. The time constant for the exponential decay is given by…”

Capillary electrophoresis of proteins 2003–2005

“…In an approach reminiscent of MEKC, liposomes based on 1-palmitoyl-2-oleyolsn-glycero-3-phosphocholine were used as pseudostationary phase for CE of basic proteins [54,90]. Gradient field electrophoresis has been proposed to improve separation of proteins, and used for CZE of R-phycoerythrin [91].…”