USE OF CAPILLARY ELECTROPHORESIS ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY IN THE ANALYSIS OF SYNTHETIC PEPTIDES

We have constructed a capillary electrophoresis (CE) system with UV de tection and have successfully interfaced it to an electrospray ionizat ion mass spectrometry (ES-MS) system. A synthesized fragment of heregu lin-beta (212-226) was thought to be a single component by re-injectio n into an HPLC system, but results from CE-UV-ES-MS indicated that a d ehydration product was present in the desired peptide sample. A synthe tic heregulin-alpha (177-241) was isolated by preparative HPLC, but re -injection on an analytical system indicated a tailing peak. CE-UV-ES- MS indicated a mixture whose two major components were of the same nom inal molecular mass (within experimental error), suggesting the presen ce of an isomer or a deamidation product. The results show that CE-UV- ES-MS can be used as an orthogonal analytical technique to solve pract ical problems encountered in peptide synthesis laboratories.