Tryptic digest mapping by gradient capillary electrochromatography

A high performance liquid chromatography (HPLC) system complemented with T- split, capillary detection cell and a high voltage power supply was used fo r peptide mapping by gradient electrochromatography and nanoliquid chromato graphy (nano-LC). With capillary columns of 100 mu m ID, 6 cm packed with o ctadecylated 1.5 mu m silica particles, the typical analysis time was appro ximately 10-15 min. The resolution of a tryptic digest of cytochrome c obta ined by electrochromatography at 100 kV/m was superior compared to the anal ysis by nano-LC. Bubble formation caused by Joule heating at currents up to 100 mu A was successfully suppressed by using a resistor capillary of 25 m u m ID connected to the outlet of the packed column.