IDENTIFICATION OF PROTEINS BY CAPILLARY ELECTROPHORESIS TANDEM MASS-SPECTROMETRY - EVALUATION OF AN ONLINE SOLID-PHASE EXTRACTION DEVICE

Capillary electrophoresis-tandem mass spectrometry has been used succe ssfully for the analysis of complex peptide mixtures. The method is li mited by a relatively high concentration limit of detection and by mat rix effects. Here we describe on-line coupling of a solid-phase microe xtraction device to a capillary electrophoresis-tandem mass spectromet ry system. The performance of the integrated instrument was evaluated for the identification of proteins by their amino acid sequence. We re port that the concentration limit of detection was improved at least 1 000 fold to the low attomole/mu l range and that matrix effects were m inimized by extensive sample clean-up during solid-phase extraction. W e demonstrate that the implementation of a solid-phase extraction devi ce significantly enhances capillary electrophoresis-tandem mass spectr ometry as a method for the identification of low abundance proteins is olated from high-resolution two-dimensional polyacrylamide gels.