Comprehensive two-dimensional chromatography and capillary electrophoresis coupled with tandem time-of-flight mass spectrometry for high-speed proteome analysis

A comprehensive two-dimensional capillary liquid chromatography and capillary zone electrophoresis system coupled with tandem matrix assisted laser desorption/ionization-time of flight-time of flight-mass spectrometry (MALDI-TOF-TOF-MS) proteomics analyzer is presented. Protein/peptide samples were separated by capillary high-performance liquid chromatography (cHPLC). The effluents from cHPLC (the first dimension) were continuously transferred into capillary zone electrophoresis (CZE, the second dimension) through a novel valve-free hydrodynamic sampling interface. The CZE effluents were mixed with alpha-cyano-4-hydroxycinnamic acid (CHCA) matrix sheath flow via CE-MALDI interface, and then directly deposited on the MALDI target at a 3 s time-interval for further MS analysis. The high efficiency of the overall system was demonstrated by analysis of proteins in D-20 (human hepatocellular carcinoma model in nude mice with high metastatic potential) liver cancer tissue. More than 300 proteins were identified, which proved the system potential for high-throughput analysis and application in proteomics.