Capillary electrophoresis of peptides and proteins at neutral pH in capillaries covalently coated with polyethyleneimine.

Two procedures for the derivatization of the inner wall of fused-silica capillaries for the analysis of peptides and proteins by capillary electrophoresis (CE) at neutral pH are presented. In the first procedure, polyethyleneimine (PEI) is covalently attached to the capillary wall. In the second procedure, PEI is additionally cross-linked. We present analysis of standard peptides and proteins by CE using the coated capillaries. These coatings will have application for the separation of protein complexes at neutral pH, prior to analysis by electrospray mass spectrometry.