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

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.

A "Brick" Mass Spectrometer with Photoionization for Direct Analysis of Trace Volatile Compounds.

With high portability and favorable performance, miniature mass spectrometers have become one of the most attractive tools for on-site analysis of trace volatile compounds. Based on the "Brick" mass spectrometer (BMS) developed previously, a hand-held BMS integrated with a photoionization source (PI-BMS) was developed in this study for volatile compound analysis. With compact dimensions of 30 cm × 18.5 cm × 27.6 cm (length × width × height), the PI-BMS was equipped with a 10.6 eV UV lamp and capable of generating molecular ions. The capabilities of qualitative and quantitative analyses for different volatile samples were demonstrated and characterized. Under optimized conditions, high detection sensitivity in open air was obtained for the PI-BMS with a limit of detection (LOD) of ∼10 ppbv. As demonstrations of mixture analysis, four different fresh fruits were directly analyzed using PI-BMS, observing characteristic mass spectra for each type of fruit.