HYDROGEN-BONDING INTERACTION IN CAPILLARY ELECTROPHORESIS USING POLYETHER MATRICES

Polyethylene glycol (PEG) serves as a novel matrix in capillary electrophoresis. The purpose of this work was to explore some evidence for hydrogen-bonding complex formation between analytes and PEG in the separation system using benzoic acids as model analytes. An increase in the column temperature resulted in a significant decrease in the interaction between PEG and substituted benzoic acids with hydrogen-donating groups. Addition of urea suppressed the interaction. NMR spectra of phenol and salicylic acid in the presence of PEG in (CHCl3)-H-2 showed an obvious electrostatic interaction, probably a hydrogen-bonding interaction, between the hydroxyl protons of the analytes and PEG. These results strongly support the contention that hydrogen-bonding interaction between the polyether segments of PEG and the hydrogen-donating groups of analytes occurs in the separation systems. Some other minor interactions controlling the separation are also described.