SHEATHLESS CAPILLARY ELECTROPHORESIS ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY USING 10 MU-M ID CAPILLARIES - ANALYSES OF TRYPTIC DIGESTS OF CYTOCHROME-C

The analyses of tryptic digest of proteins present a difficult challen ge to the analytical chemist due to the wide range of molecular masses and hydrophobicities of the peptides produced. In this study, we demo nstrate the separation of tryptic digests of bovine, Candida krusei an d equine cytochrome c using a new electrospray ionization (ESI) interf ace for CE-MS that does not require additional sheath make-up fluid or mechanical assistance to aid the ESI process. The utility of this new CE-ESI-MS interface is demonstrated using a 10 mu m I.D. CE capillary where the injected sample amounts are in the 30 femtomole (of protein ) region. The CE electroosmotic flow rates when aminopropylamine treat ed capillaries are utilized are in the 10 nI/min region for a relative ly conductive buffer system (0.01 M ammonium acetate-acetic acid buffe r system, pH 4.4 and a 300 V/cm field strength).