DIRECT ELECTROSPRAY ION CURRENT MONITORING DETECTION AND ITS USE WITHONLINE CAPILLARY ELECTROPHORESIS MASS-SPECTROMETRY

A novel detection scheme for use with the capillary electrophoresis-el ectrospray ionization interface is presented, based upon the direct me asurement of electrospray ion current after expansion into vacuum, tha t is shown to provide the basis for a simple detector or for simultane ous dual detection with mass spectrometry. The utility of this novel d ual-detection scheme is illustrated with capillary electrophoresis Fou rier transform ion cyclotron resonance (FTICR) mass spectrometry in wh ich spectra are acquired only when a solute zone elutes from the CE ca pillary. This acquisition scheme affords significantly improved sensit ivity and permits the acquisition of longer time domain signals withou t sacrificing separation efficiency. Mass resolving power in excess of 10(5) (fwhm) is demonstrated by FTICR for components from a peptide/p rotein mixture composed of analytes with molecular masses ranging from 2 to 29 kDa.