title: Modification of ion chromatographic separations by ionic and nonionic surfactants.
abstract: New findings are reported on simple ways to modify an ordinary HPLC column to obtain efficient ion chromatographic (IC) separations. Permanently coating a column with an ionic surfactant is known to produce an effective column for IC. We now show that incorporation of a nonionic surfactant in the coating, or coating in separate layers, results in a dramatic reduction of ion retention times and gives sharper peaks. Dynamic coating by incorporating a small amount of an alcohol, diol or zwitterion in the aqueous mobile phase permits good separations of alkanecarboxylic acids. A mobile phase containing a quaternary ammonium cation and a zwitterion anion provides excellent separations of common anions on a silica C18 column. An aqueous eluent containing a mixture of a zwitterion 4-(2-hydroxyethyl) acid and methanesulfonic acid can be used in conjunction with a standard cation exchange column. After passing through a membrane suppressor, the mobile phase has a slightly acidic pH, permitting divalent transition metal ions (as well as others) to be detected by conductivity.
authors.affiliation: Ames Laboratory, US Department of Energy, Department of Chemistry, Iowa State University, 332 Wilhelm Hall, Ames, IA 50011, USA. kniss@ameslab.gov
authors.forename: James S
authors.initials: JS
authors.lastname: Fritz
authors.forename: Zhu
authors.initials: Z
authors.lastname: Yan
authors.forename: Paul R
authors.initials: PR
authors.lastname: Haddad
mesh_terms: D000838:Anions; D002264:Carboxylic Acids / Q000302:isolation & purification; D002412:Cations; D002594:Cetylpyridinium; D002845:Chromatography / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008698:Mesylates; D010472:Perchlorates; D000644:Quaternary Ammonium Compounds; D012822:Silicon Dioxide; D017670:Sodium Compounds; D013501:Surface-Active Agents
chemical_list: D000838:Anions; D002264:Carboxylic Acids; D002412:Cations; D007202:Indicators and Reagents; D008698:Mesylates; D010472:Perchlorates; D000644:Quaternary Ammonium Compounds; D017670:Sodium Compounds; D013501:Surface-Active Agents; C045880:methanesulfonic acid; C046112:didodecyldimethylammonium; D012822:Silicon Dioxide; C031068:sodium perchlorate; D002594:Cetylpyridinium