Capillary electrophoresis tandem mass spectrometry with array detection

Mixtures of standard compounds of biological interest were analyzed by capi llary electrophoresis in conjunction with tandem four-sector mass spectrome try (MS/MS) using an array detector. Capillary electrophoresis offers extre mely high separation efficiencies while array detection allows for the simu ltaneous acquisition of a large fraction of a tandem mass spectrum and high utilization of the sample ions produced. Consequently, improvements in sen sitivity and structural information were observed for the combined techniqu es in comparison to similar measurements with a four-sector and a single-po int detector. Coaxial continuous-flow fast atom bombardment was used to cre ate (M + H)(+) precursor ions of the separated analytes and their product i on spectra were acquired from femtomole levels in electrophoretic real-time , The limit-of-detection for the acquisition of MS/MS data from electrophor etically-separated peptides was 35-100 fmol, The MS/MS data acquired at the se levels showed cleavages of the peptide backbone (i.e. to give a and y io ns) and production of immonium ions from the constituent amino acids. Acqui sition of the spectra via the array detector is more routine acid, at the 1 00 femtomole level, provides more structurally informative ions and yields better ion statistics than comparable spectra acquired with a point detecto r.