Capillary electrochromatography/nanoelectrospray mass spectrometry for attomole characterization of peptides

The successful coupling of capillary electrochromatography (CEC) to an ion trap mass spectrometer via a nanoelectrospray interface (nESI) is described . Using a conductively coated tip butted to the end of a CEC column, it was possible to obtain a stable spray without any sheath liquid being employed . Selected small peptides were separated with CEC columns (100 mu m i.d./25 cm long) packed with 3 mu m Hypersil C8 or C18 bonded silica particles wit h an eluent composed of ammonium acetate/acetonitrile. Peptide mixtures of desmopressin, peptide A, oxytocin, carbetocin and [Met(5)]-enkephalin were detected in the mid-attomole range, which is the lowest amount analyzed usi ng CEC combined with MS detection. It was also observed that sensitivity ca n be compromised at higher separation voltages. We demonstrate that CEC/nES I-MS, at the current stage of development, represents one of the most sensi tive systems for peptide analysis. Copyright (C) 2000 John Wiley & Sons, Lt d.