A capillary electrochromatography–electron spray ionization-mass spectrometry method for simultaneous analysis of charged and neutral constituents of a hepatocarcinoma cell metabolome

Although metabolome research is a rapidly expanding field in the postgenomic era, no single method exists for complete analysis of all the constituents of a metabolome. In this study, we developed a metabolome analysis method using a combination of capillary electrochromatography and electrospray ionization-mass spectrometry. The capillary electrochromatography column was prepared by surface modification of silica compounds (tetraethoxysilane and octyltriethoxysilane) in a fused-silica capillary column. The method was used to separate more than 100 charged and neutral compounds simultaneously. When 1 mM formic acid was used as the eluent, the cationic compounds were eluted rapidly, and then neutral and anionic compounds were eluted (in that order). The developed system was used to analyze the metabolome of a human hepatocellular carcinoma cell line (HepG2). Thirty-three peaks were detected, and eighteen compounds were identified, including marker compounds of hepatocellular cell activity, such as creatinine and homocysteine. Thus, the system was useful not only for metabolome analysis but also for diagnostic measurements of cell function.