Separation of polyethylene glycol-modified proteins by open tubular capillary electrochromatography.

This study involves the characterization of six polyethylene glycol-modified proteins by open tubular capillary electrochromatography, a high-resolution, versatile and reproducible technique for the analysis of biomolecules and pharmaceuticals. Optimized conditions were obtained with respect to type of capillary modification (cholesterol and octadecyl), applied voltage (+20 and -20 kV), buffer pH (2.14-8.14) and addition of methanol modifier to the mobile phase. Electrochromatograms were obtained with both cathodic and anodic applied electric fields. In the case of one PEG-protein, superoxide dismutase, a comparison was made to a previous study. Reproducibility and column lifetime were also evaluated in assessing the usefulness of the method.