title: Stability and effectiveness of linear polyacrylamide capillary coating to suppress EOF in acidic media in the presence of surfactants, ionic liquids and organic modifiers.
abstract: Because of its high hydrophilicity, linear polyacrylamide (LPA) has often been used as a coating to suppress electroosmotic flow (EOF) in capillary electrophoresis (CE); however, its stability and effectiveness in acidic media, with or without organic modifiers, surfactants or ionic liquids is not well documented. In this work, the adequacy of LPA coating to suppress EOF in those different conditions was studied. It was shown that electroosmotic mobilities (µEO) did not change for at least 70h of non-stopped operation in all the tested conditions and the coating was stable. It was also shown that LPA coating efficiently suppresses EOF in acidic media (pH 4.0, 3.1, and 2.3) with or without organic modifiers (50% methanol or acetonitrile, ACN), as measured µEO values were between 18 and 84 times lower than those obtained with bare fused-silica capillaries. In acidic media with anionic surfactant (50mM sodium dodecylsulfate, SDS), ionic liquid (25 mM dodecyldimethylimidazolium bromide) or both SDS and ACN (buffer pH 2.1/ACN (8:2, v/v)+50mM SDS) EOF was reduced to a magnitude lower than with bare fused-silica capillaries, even though slight adsorptions of these surfactants were observed. LPA showed its superiority to hydroxypropyl cellulose, for which marked adsorption occurred because of its lower hydrophilicity.
authors.affiliation: PSL Research University, ESPCI ParisTech, Laboratory of Analytical and Bioanalytical Sciences and Miniaturization, UMR CBI 8231, 10 rue Vauquelin, 75231 Paris cedex 05, France; CNRS, UMR 8231, Paris, France.
authors.forename: Miriam
authors.initials: M
authors.lastname: Beneito-Cambra
authors.affiliation: Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), Paris, France; UPMC, Sorbonne Universités, Paris, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Anres
authors.affiliation: PSL Research University, ESPCI ParisTech, Laboratory of Analytical and Bioanalytical Sciences and Miniaturization, UMR CBI 8231, 10 rue Vauquelin, 75231 Paris cedex 05, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Vial
authors.affiliation: Chimie ParisTech, Laboratory of Physicochemistry of Electrolytes, Colloids and Analytical Sciences (PECSA), Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Gareil
authors.affiliation: PSL Research University, ESPCI ParisTech, Laboratory of Analytical and Bioanalytical Sciences and Miniaturization, UMR CBI 8231, 10 rue Vauquelin, 75231 Paris cedex 05, France; CNRS, UMR 8231, Paris, France. Electronic address: nathalie.delaunay@espci.fr.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Delaunay
keywords: Capillary coating; Capillary electrophoresis (CE); Electroosmotic flow suppression; Ionic liquids