Premium
Protonated diamines as anion‐binding agents and their utility in capillary electrophoresis separations
Author(s) -
Noblitt Scott D.,
Speights Rachel M.,
Henry Charles S.
Publication year - 2011
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201100252
Subject(s) - chemistry , capillary electrophoresis , protonation , moiety , aqueous solution , affinities , electrolyte , ionic bonding , electrophoresis , ion , analyte , affinity electrophoresis , ionic strength , computational chemistry , inorganic chemistry , chromatography , organic chemistry , stereochemistry , electrode , affinity chromatography , enzyme
Capillary zone electrophoresis is a proven method for separating small ions because of the inherent charge and differences in mobility of these analytes. Despite its resolving power, CZE can be insufficient for separating ions with similar mobilities. One remedy is to modify mobilities via the addition of background electrolyte complexation agents. However, this approach is not straightforward for inorganic anions, which lack complexation options. To address this shortfall, the diprotonated diamine moiety was investigated for complexation of dianions. Dicationic diamines significantly complexed dianions, and this interaction was not purely electrostatic in nature because affinities varied with dianion identity. Aqueous association constants were measured with affinity capillary electrophoresis (ACE) and found to be similar in magnitude but different in selectivity to those of dianions with magnesium ion. Binding was also investigated for zwitterionic buffers containing the protonated diamine moiety. Zwitterions exhibited binding constants as high as 18 M −1 (30‐mM ionic strength). This work discusses the observed binding constants and their potential usefulness in CZE separations of inorganic anions. Also covered are improvements to ACE methodology and an evaluation of some of the assumptions employed.