Metabolomics Platform with Capillary Electrophoresis Coupled with High-Resolution Mass Spectrometry for Plasma Analysis

Metabolome
analysis using capillary electrophoresis (CE) coupled
with high-resolution mass spectrometry (HRMS) has the potential to
improve coverage of metabolite detection because of its high selectivity
and sensitivity. Configuration of the interface between CE and HRMS
to meet the ground connection is essential for enabling independent
regulation of the electrical currents in the CE and electrospray field.
In the present study, we applied an electrospray-ionization adapter
equipped with a grounded nebulizer to CE-HRMS and tested the analytical
performance for 34 charged compounds. The extracted-ion electropherograms,
consisting of seven sets of isomers, showed reasonable peak shapes
and separation for the annotation of each metabolite. The levels of
34 target analytes in a standard mixture were determined with a dynamic
range of at least 102, maintaining linearity with r2 > 0.9. The repeatability and intermediate
precision above the lower limit of quantification showed the relative
standard deviation to be lower than 20%. In the spike-recovery experiment,
27 of the 34 metabolites in plasma extract were recovered at a rate
of 80 to 120%, suggesting high accuracy. Furthermore, we assessed
the feasibility of our platform in metabolome analysis using human-plasma
extract. The results showed successful detection of 270 metabolites,
indicating the potential of our platform to yield higher coverage
of the metabolome. In addition, analysis of dilution integrity demonstrated
the quantitative ability of metabolome analysis with CE-HRMS, although
the existence of saturation or matrix effects were seen in the case
of 33 of the metabolites. This study indicates that our platform has
great potential for large-scale metabolome analysis of plasma for
biological studies and clinical biomarker screening.