Affinity capillary electrophoretic studies of complexation between dextrinoligomers and polyiodides

Capillary electrophoresis (CE) has been applied to the study of complexatio n between dextrins and polyiodides. A baseline separation of fluorescently labeled dextrin oligomers has provided a unique platform for the observatio n of a contribution of single oligomers to the complexation process that co uld previously be measured only in bulk. The complex formation was easily r ecognized through comparison of peak migration times and peak shapes in the presence and absence of polyiodides. The degree of polymerization (DP) num ber was found crucial in the binding process, but the I-2/I- ratio in a sol ution also appeared to determine the nature of complexation. The effects of buffer pH and ionic strength upon complexation were also briefly investiga ted. Diode-array spectra in the visible wavelength range confirmed the diff erential complexation of unlabeled maltodextrins with different DP values a fter a CE iodine affinity separation. C-13-nuclear magnetic resonance (NMR) spectral data on differently sized dextrin fractions were found to be in g ood agreement with the results from CE measurements.