Electrophoretic separation of proteins on dynamically treated fused silica capillaries

CZE is a very useful tecnique for protein analysis, but some difficults are encountered for their strong adsorption on the negatively charged. silica walls. The static deactivation of capillaries via polymeric coating is very laborious and generally problematic (because of the capillary clogging and short life). The dynamic deactivation is very fast and good separation can be reached. In this work we have investigated the separation of basic proteins using as deactivating solution the background electrolyte containing a polyamine or a surfactant.The polyamine, when protonated, is attracted from the negatively charged capillary walls which are neutralized. The following polyamines: 1,3 diaminopropane, bis-(3-aminopropyl)amine, triethylenetetramine and the cationic surfactant cetyltrimethylammonium bromide were tested. Each of these compounds is able to deactivate the fused silica capillary and the electroosmotic flow can be decreased and even reversed. In the best working conditions well resolved and symmetrical peaks are obtained. The RSD% of migration times is about 1%.