title: Deformations of overloaded bands under pH-stable conditions in reversed phase chromatography.
abstract: It has recently been demonstrated, using mathematical models, how peculiar overloaded band profiles of basic compounds are due to the local pH in the column when using low capacity buffers. In this study, overloaded peak shapes resulting after injection of carefully pH matched samples close to the pK(a) of the chosen solute are investigated primarily on two columns; one hybrid silica C18 column (Kromasil Eternity) and one purely polymeric column (PLRP-S), the latter lacking C18 ligands. It was found that distorted peaks of the basic test compound appear even though there is no difference in pH between the injected sample solution and the eluent; the previous explanation to why these effects occur is based on a pH mismatch. Thus, the unusual band shapes are not due to an initial pH difference. Furthermore, it was observed that the effect does not appear on polymeric columns without C18 ligands, but only on columns with C18 ligands, independently of the base matrix (silica, hybrid silica, polymeric).
authors.affiliation: Department of Physical and Analytical Chemistry, Uppsala University, BMC Box 599, SE-751 24 Uppsala, Sweden.
authors.forename: Lena
authors.initials: L
authors.lastname: Edström
authors.forename: Jörgen
authors.initials: J
authors.lastname: Samuelsson
authors.forename: Torgny
authors.initials: T
authors.lastname: Fornstedt
mesh_terms: D000327:Adsorption; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D008790:Metoprolol / Q000737:chemistry; D008956:Models, Chemical; D011137:Polystyrenes / Q000737:chemistry; D020005:Propanols / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012822:Silicon Dioxide
chemical_list: D011137:Polystyrenes; D020005:Propanols; D000644:Quaternary Ammonium Compounds; C432006:divinylbenzene-polystyrene copolymer; C439395:1-phenylpropanol; C000168:benzyltrimethylammonium; D012822:Silicon Dioxide; D008790:Metoprolol