title: Conductivity properties of carrier ampholyte pH gradients in isoelectric focusing.
abstract: The conductivity properties of natural pH gradient created by carrier ampholytes were studied during the process of isoelectric focusing (IEF). IEF was performed in capillaries (10-30 mm long) or in microchips with the same channel length. A 10-30x reduction of the conductivity of the separation medium was observed during the establishment of pH gradient. Results obtained using different IEF voltages indicate that there is a nonlinear relationship between the conductivity of an established pH gradient and the applied electric field. Our theoretical analysis using a simplified model generated values that reasonably agree with the experimental data. In addition, we found that above a certain electric field ( approximately 300 V/cm), resolution does not increase with the applied voltage as predicated; we observed band-broadening and gel breakdown. The approach presented in this work can be used for optimization of the IEF separation and judicious selection of IEF conditions.
authors.affiliation: Department of Mechanical and Aerospace Engineering, McKnight Brain Institute, University of Florida, Gainesville 32611, USA.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Stoyanov
authors.forename: Champak
authors.initials: C
authors.lastname: Das
authors.forename: Carl K
authors.initials: CK
authors.lastname: Fredrickson
authors.forename: Z Hugh
authors.initials: ZH
authors.lastname: Fan
mesh_terms: D000665:Ampholyte Mixtures; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing / Q000379:methods*; D046210:Microfluidic Analytical Techniques
chemical_list: D000665:Ampholyte Mixtures