Modification of ion chromatographic separations by ionic and nonionic surfactants.
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.
Fritz
James S
JS
Ames Laboratory, US Department of Energy, Department of Chemistry, Iowa State University, 332 Wilhelm Hall, Ames, IA 50011, USA. kniss@ameslab.gov
Yan
Zhu
Z
Haddad
Paul R
PR
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
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