Selective enrichment of low-abundance peptides in complex mixtures by elution-modified displacement chromatography and their identification by electrospray ionization mass spectrometry.

Trace components were selectively enriched and detected in the tryptic digest of recombinant human growth hormone using elution-modified displacement chromatography, a hybrid technique combining features of elution and displacement chromatography. Based on the retention behavior of sample components in the elution mode, rapid and selective trace enrichment and high-resolution separation was achieved in a single step by utilizing appropriate combinations of an eluent such as aqueous acetonitrile with the displacer. Mass spectral and chromatographic analysis of displacement zones revealed up to 400-fold enhancement of the concentration of some low-abundance sample components. Potential application of this technique in proteomics to augment the sensitivity of LC-MS and 2-D gel electrophoretic approaches for the detection of biologically important low-abundance species is discussed.