title: Effects of mobile phase composition on retention and selectivity in achiral supercritical fluid chromatography.
abstract: In supercritical fluid chromatography (SFC), the effects of adding a co-solvent to carbon dioxide are numerous. In this work, the changes in retention and selectivity occurring when the nature of the co-solvent (methanol, ethanol, isopropanol, acetonitrile) in the SFC mobile phase is varied, are studied on seven columns with different stationary phase chemistry (cyanopropyl-, pyridine-ethyl-, phenyl-oxypropyl-, phenyl-propyl-, phenyl-hexyl-, pentafluorophenyl-propyl- and octadecyl-bonded silica). Hierarchical cluster analysis and quantitative structure-retention relationships with the solvation parameter model are employed to evaluate these effects, based on the observed retention for over a hundred probe compounds. It appears that some columns are somewhat more affected than others by the change of solvent nature. Acetonitrile induces the strongest differences, essentially due to its poor capabilities as an eluent for bases and possibly because it does not adequately cover residual silanol groups. Ethanol appears to be a possible green alternative to the most-used methanol. Some hints on a possible partition-adsorption mixed mechanism are offered. Finally, sample applications with three different test mixtures relevant to cosmetic and pharmaceutical applications (flavanones, non-steroidal anti-inflammatory drugs and barbiturates) are presented.
authors.affiliation: Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS UMR 7311, Pôle de Chimie, B.P. 6759, rue de Chartres, 45067 Orléans cedex 2, France. caroline.west@univ-orleans.fr
authors.forename: Caroline
authors.initials: C
authors.lastname: West
authors.forename: Eric
authors.initials: E
authors.lastname: Lesellier
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000894:Anti-Inflammatory Agents, Non-Steroidal; D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D000431:Ethanol / Q000737:chemistry; D044950:Flavanones / Q000032:analysis
chemical_list: D000097:Acetonitriles; D000894:Anti-Inflammatory Agents, Non-Steroidal; D044950:Flavanones; D000431:Ethanol; C032159:acetonitrile
keywords: Method development; Mobile phase composition; Selectivity; Solvation parameter model; Stationary phases; Supercritical fluid chromatography