Studies in capillary zone electrophoresis with a post-column multiple capillary device for fraction collection and...

A new approach involving the stepwise increase in electroosmotic flow during analysis in capillary zone electrophoresis is introduced and evaluated in the rapid separations of proteins and peptides. The stepwise increase in electroosmotic flow is based on the principle of coupled capillaries in series having different flow characteristics, a concept that was introduced recently by our laboratory. To produce stepwise changes in electroosmotic flow during analysis, a post-column multiple capillary device, which allowed the switching between several coupled capillary systems, was designed and constructed in-house. The utility of the multiple capillary device was also demonstrated and extended to fraction collection of separated analytes in short capillary segments. The fraction collection in capillaries facilitated the quantitative transfer of the collected fractions to high performance liquid chromatography (HPLC) for further analysis or to mass spectrometry (MS) for structural determination. The off-line combination of capillary zone electrophoresis with HPLC or MS utilized commercial instruments without the need of expensive interfacing designs.