EVALUATION OF ADSORPTION PRECONCENTRATION CAPILLARY-ZONE-ELECTROPHORESIS NANOELECTROSPRAY MASS-SPECTROMETRY FOR PEPTIDE AND GLYCOPROTEIN ANALYSES

The use of an on-line adsorption preconcentrator coupled with capillar y zone electrophoresis/nanoelectrospray mass spectrometry (PC/CZE/nESM S) is described for the analysis of peptides and protein digests. The investigation was focused on the production of disposable preconcentra tors made of large particle size (40 mu m irregular packing), thereby eliminating the use of a retaining frit without loss of performance. T hese preconcentration devices were made of commercially available comp onents which can be easily interfaced to current CZE/nESMS systems, Pr actical issues such as the composition of the stationary phase, the el ution volume and sample breakthrough and carry-over were evaluated in order to optimize the analytical performance of this technique, Under optimized elution conditions, the PC/CZE/nESMS technique provided sepa ration efficiencies in excess of 100 000 theoretical plates for a samp le loading of 8 mu l. Sample carry-over was minimized by proper recond itioning of the preconcentrator prior to the CZE separation, Alternati vely, the sample carry-over resulting from small elution volumes could be used advantageously to provide multiple analyses from a single inj ection of sample. The application of this technique is demonstrated fo r the analysis of proteolytic peptides from a Bauhinia purpurea lectin at a concentration level of 30 nM, Further structural information was obtained using on-line tandem mass spectrometry to elucidate the stru cture of N-linked glycans and the amino acid sequences of the glycopep tides. (C) 1998 John Wiley & Sons, Ltd.