Integration of a liquid-phase ion trap with a miniature mass spectrometer

Highlights: • A simplified liquid-phase ion trap was integrated with a home-built miniature mass spectrometer. • Detection sensitivity of the miniature mass spectrometer was improved by ∼10 folds. • This liquid-phase ion trap was also capable of separating ions according to their hydrodynamic radii and effective charges. Liquid-phase ion trap was recently developed in our group, which has simple configuration and could realize ion manipulations in solution. In this study, a simplified liquid-phase ion trap was integrated with a home-built miniature mass spectrometer for enhanced analytical performances. Ion enrichment and separation could be realized in the liquid-phase ion trap before mass spectrometry analyses. As a result, detection sensitivity of the miniature mass spectrometer could be improved by ∼10 folds. Besides ion intensity enrichment, this liquid-phase ion trap was also capable of separating ions according to their hydrodynamic radii and effective charges. This capability was demonstrated by separating small molecules in protein background and isobaric peptide ions. Furthermore, target analytes in salt solutions and urine were also enriched and detected by the miniature mass spectrometer. Results suggest that the coupling of liquid phase ion trap with miniature mass spectrometer is a powerful technique, which could be beneficial for low abundant target molecule analysis in practical applications.