Capillary-zone electrophoresis/fast-atom bombardment mass spectrometry: design of an on-line coaxial continuous-flow interface.

An on-line coaxial continuous-flow capillary-zone electrophoresis/fast-atom bombardment mass spectrometry (CZE/FAB-MS) interface is described. This interface is shown to be capable of acquiring mass spectra in an on-line fashion from low femtomole amounts of peptides while maintaining high (hundreds of thousands of plates) electrophoretic separation efficiencies. Active electrophoretic transport of the analytes directly to the FAB probe tip obviates the need for a transfer line from the end of the CZE capillary to this point, and thereby precludes the zone broadening that would otherwise occur both within such a transfer line and in the connections between the CZE column and the transfer line. The capability of acquiring an on-line tandem mass spectrometry (MS/MS) spectrum of an electrophoretically separated analyte using this interface is also demonstrated.