Next-generation capillary electrophoresis-mass spectrometry approaches in metabolomics

Capillary electrophoresis-mass spectrometry has shown considerable potential for profiling polar ionogenic compounds in metabolomics. Hyphenation of capillary electrophoresis to mass spectrometry is generally performed via a sheath-liquid interface. However, the electrophoretic effluent is significantly diluted in this configuration thereby limiting the utility of this method for highly sensitive metabolomics studies. Moreover, in this set-up the intrinsically low-flow property of capillary electrophoresis is not effectively utilized in combination with electrospray ionization. Here, advancements that significantly improved the performance of capillary electrophoresis-mass spectrometry are considered, with a special emphasis on the sheathless porous tip interface. Attention is also devoted to various technical aspects that still need to be addressed to make capillary electrophoresis-mass spectrometry a robust approach for probing the polar metabolome.