Both cationic and anionic polymeric additives were used for the capillary electrophoretic separation of proteins in food samples. The cationic polyelectrolyte polydiallyldimethylammonium chloride was more effective in minimizing protein-wall interactions at pH 3 than at pH 7, presumably due to greater repulsion between the adsorbed polymer and proteins. Improved resolution was observed in the presence of the co-additive sodium octanesulphonate, presumably due to ion-pairing interactions with protein sample components. The anionic polymer dextran sulfate produced relatively high efficiencies, 120 000-180 000 theoretical plates, for protein separation, presumably because the polymer adsorbed to the capillary wall, rendering the surface more hydrophilic. In addition to reduced protein-wall interactions, improved resolution was observed, presumably due to analyte-polymer ion-exchange/ion-pairing interactions. When poly(vinyl sulphonic acid) was used instead of dextran sulfate, broader profiles were obtained and fewer components were resolved, presumably due to reduced wall deactivation that is related to the lower hydrophilicity of poly(vinyl sulphonic acid). Copyright (C) 1998 Elsevier Science B.V.
Bibliographical noteFunding Information:
This work was supported by a Research Grant from the Natural Sciences and Engineering Research Council. Yung-Fong Cheng of Waters, is gratefully acknowledged for the generous donation of the Quanta 4000 instrument. E. Leblanc and R.J. LeBlanc of the Department of Agriculture, Food and Nutritional Science of the University of Alberta graciously provided the tissue samples.
Copyright 2007 Elsevier B.V., All rights reserved.
- Food analysis