A Tapered Capillary-Based Contactless Atmospheric Pressure Ionization Mass Spectrometry for On-Line Preconcentration and Separation of Small Organics

Capillary electrophoresis (CE) is an effective technique for the separation of different analytes. Moreover, online preconcentration of trace analytes in the capillary for CE analysis has been demonstrated. CE and capillary electrochromatography (CEC) are suitable for the separation of analytes with similar polarities. Given that CE and CEC are only used to separate small-volume samples, sensitive mass spectrometry (MS) is a suitable detection tool for CE and CEC. Contactless atmospheric pressure ionization (C-API) is a continuous flow ion source that only uses a short capillary as the ionization emitter operated at atmospheric pressure for MS analysis. In this study, we demonstrated the feasibility of hyphenating CE/CEC with C-API-MS by using a short and tapered capillary as the interface. The short capillary (a few centimeters) can function as the separation/preconcentration tube and the ionization emitter. This hyphenated technique can be used to analyze small organics within a few minutes. The suitability of using the hyphenated technique for online preconcentration, separation, and quantitative analysis for small organics is demonstrated in this study.