title: Influence of the ionic strength of acidic background electrolytes on the separation of proteins by capillary electrophoresis.
abstract: The ionic strength is one of the key parameters for optimizing CE separations. However, only a few data are available in the literature about the ionic strength effect on the separation of proteins. The effect of ionic strength on separation performances is rather complex since many different parameters are involved: such as the protein effective mobility, the electroosmotic mobility, the separation efficiency via the electromigration dispersion, as well as the viscosity and temperature of the background electrolyte. In the present work, the influence of ionic strength on the electrophoretic separation of five model proteins has been investigated in acidic conditions, on successive multi-ionic layers coated capillary, in counter-electroosmotic mode with anodic electroosmotic flow. The decrease in effective and electroosmotic mobilities with increasing ionic strength were compared using the slope-plot approach, which is very helpful for understanding the observed changes in apparent selectivity and resolution. The relative decrease of the protein effective mobility was about 30-40% of the mobility determined at 5mM ionic strength per ionic strength decade. It was found that relatively low ionic strength (∼5-10mM) was preferable to optimize the overall separation of the five model proteins.
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM, UMR 5247, CNRS, Université de Montpellier, ENSCM), Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France.
authors.forename: Samya
authors.initials: S
authors.lastname: Bekri
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM, UMR 5247, CNRS, Université de Montpellier, ENSCM), Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Leclercq
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM, UMR 5247, CNRS, Université de Montpellier, ENSCM), Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France. Electronic address: herve.cottet@umontpellier.fr.
authors.forename: Hervé
authors.initials: H
authors.lastname: Cottet
mesh_terms: D004573:Electrolytes / Q000737:chemistry*; D053841:Electroosmosis; D019075:Electrophoresis, Capillary / Q000379:methods; D007782:Lactoglobulins / Q000302:isolation & purification; D009113:Muramidase / Q000302:isolation & purification; D009211:Myoglobin / Q000302:isolation & purification; D009994:Osmolar Concentration; D011506:Proteins / Q000302:isolation & purification*; D012259:Ribonuclease, Pancreatic / Q000302:isolation & purification
chemical_list: D004573:Electrolytes; D007782:Lactoglobulins; D009211:Myoglobin; D011506:Proteins; D012259:Ribonuclease, Pancreatic; D009113:Muramidase
keywords: Capillary coatings; Electrophoretic mobility modeling; Ionic strength effect; Polyelectrolyte multilayers; Protein separation; Slope plot