In this study, positively charged alkylanninosilyl monomers were used to modify the inner surface of fused silica capillaries, which subsequently were employed in capillary electrophoresis (CE) and capillary electrochromatography (CEC). The obtained surfaces yield a reversed electroosmotic flow (EOF) and have varying carbon chain lengths, that interact with the analytes and give chromatographic retention. The coating procedure is very simple and fast. The performance of the modified capillaries was evaluated regarding pH influence on EOF and chromatographic interactions. The experiments were conducted with UV and mass spectrometry (MS) and applied to the separation of various neuropeptides. The derivatized surfaces showed a linear (R-2 similar to0.99) pH dependence with isoelectric points (pl) at 8.6-8.8. Rapid separations of peptide standards and a protein digest with efficiencies as high as 5 x 10(5) plates/m were performed.