The communication discusses the use of background electrolyte solutions (BGEs) appositely tailored for separating peptides, proteins and other biomolecules by capillary electrophoresis in bare fused-silica capillary tubing. Most of the examined BGEs consist of buffers tailored for controlling the protonic equilibrium in a wide pH range and to be effective at masking the active adsorption sites of the capillaries for proteins and peptides. Such buffers are composed of either a monoprotico or a polyprotic acid in combination with an aliphatic vicinal oligoamines, similar to those originally introduced by Csaba Horváth in the late 70th as buffering agents in reversed-phase chromatography with silica-bonded phases [1], which have proven to be effective at masking the silanol adsorption sites of bare fused-silica capillaries for proteins [2] and peptides [3]. BGEs consisting of mixtures of a polyprotic acid, such as phosphoric or citric acid, and an aliphatic oligoamine, having pka values ranging from 3.5 to 9.84, display high buffering capacity in a wide pH range, modest conductivity and sufficient transparency at low UV wavelengths. The capability of the investigated buffers at suppressing the untoward interactions of proteins and peptides with the capillary wall allows the separation of these analytes in bare fused-silica capillaries both at acidic and alkaline pH values. The drastic variations of the electroosmotic flow and the inhibition of untoward interactions of basic proteins with the capillary wall, observed in a wide pH range, have been associated to the specific adsorption of the positively charged aliphatic oligoamine at the interface between the capillary wall and the electrolyte solution. Modifications in the migration behavior of basic proteins and closely related peptides observed with using different buffer's anions, such as perchlorate, phosphate and citrate, in combination with the aliphatic oligoamine, may be the result of selective interactions of these counter-ions with the considered analytes. Also discussed is the action of masking the silanol adsorption sites of bare fused-silica capillaries for proteins and peptides by a variety of ionic liquids. These salts, with melting point at or close to room temperature, have also proven to be effective at modulating the electrophoretic behavior of proteins and peptides by establishing with them either electrostatic or hydrophobic interactions [4]. References [1]Melander W. Y.; Stoveken J.; Horváth Cs. J. Chromatogr. 185 (1979) 111-127. [2]Corradini D.; Cannarsa G. LC-GC, 14 (1996) 326-332. [3]Corradini D.; Cogliandro E.; D'Alessandro, L; Nicoletti I. J. Chromatogr. A, 1013 (2003) 221-232. [4]Corradini, D.; Nicoletti I., Bonn, G.K.; Electrophoresis, 30 (2009) 1869-1876.
Influence of the background electrolyte solution on electroosmotic flow and migration behavior of biomolecules in capillary electrophoresis performed in bare fused silica tubing
Danilo Corradini
2016
Abstract
The communication discusses the use of background electrolyte solutions (BGEs) appositely tailored for separating peptides, proteins and other biomolecules by capillary electrophoresis in bare fused-silica capillary tubing. Most of the examined BGEs consist of buffers tailored for controlling the protonic equilibrium in a wide pH range and to be effective at masking the active adsorption sites of the capillaries for proteins and peptides. Such buffers are composed of either a monoprotico or a polyprotic acid in combination with an aliphatic vicinal oligoamines, similar to those originally introduced by Csaba Horváth in the late 70th as buffering agents in reversed-phase chromatography with silica-bonded phases [1], which have proven to be effective at masking the silanol adsorption sites of bare fused-silica capillaries for proteins [2] and peptides [3]. BGEs consisting of mixtures of a polyprotic acid, such as phosphoric or citric acid, and an aliphatic oligoamine, having pka values ranging from 3.5 to 9.84, display high buffering capacity in a wide pH range, modest conductivity and sufficient transparency at low UV wavelengths. The capability of the investigated buffers at suppressing the untoward interactions of proteins and peptides with the capillary wall allows the separation of these analytes in bare fused-silica capillaries both at acidic and alkaline pH values. The drastic variations of the electroosmotic flow and the inhibition of untoward interactions of basic proteins with the capillary wall, observed in a wide pH range, have been associated to the specific adsorption of the positively charged aliphatic oligoamine at the interface between the capillary wall and the electrolyte solution. Modifications in the migration behavior of basic proteins and closely related peptides observed with using different buffer's anions, such as perchlorate, phosphate and citrate, in combination with the aliphatic oligoamine, may be the result of selective interactions of these counter-ions with the considered analytes. Also discussed is the action of masking the silanol adsorption sites of bare fused-silica capillaries for proteins and peptides by a variety of ionic liquids. These salts, with melting point at or close to room temperature, have also proven to be effective at modulating the electrophoretic behavior of proteins and peptides by establishing with them either electrostatic or hydrophobic interactions [4]. References [1]Melander W. Y.; Stoveken J.; Horváth Cs. J. Chromatogr. 185 (1979) 111-127. [2]Corradini D.; Cannarsa G. LC-GC, 14 (1996) 326-332. [3]Corradini D.; Cogliandro E.; D'Alessandro, L; Nicoletti I. J. Chromatogr. A, 1013 (2003) 221-232. [4]Corradini, D.; Nicoletti I., Bonn, G.K.; Electrophoresis, 30 (2009) 1869-1876.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
