Dual Ionization Ion-Mobility Mass Spectrometry Hyphenated with Catalytic Oxygenation-Mediated Extraction

Catalytic oxygenation-mediated extraction (COME) is an environmentally friendly liquid-gas extraction technique that generates oxygen microbubbles via the catalytic decomposition of hydrogen peroxide. While corona discharge atmospheric pressure chemical ionization (APCI) is widely used for analyzing moderately polar and lower-polarity analytes with low molecular weights, secondary electrospray ionization (SESI) is a soft ionization technique that effectively ionizes polar volatile analytes. This study aims to integrate APCI and SESI with COME drift-tube ion-mobility (IM) triple quadrupole mass spectrometry (MS) to analyze volatile organic compounds (VOCs) with different physicochemical properties present in liquid matrices. The coupling of a house-built ion-mobility spectrometer with a commercial triple quadrupole mass spectrometer provides 2D separation at low cost. The user can choose one of the two ionization modes to achieve high signals with VOCs of different polarity. COME was applied to extract ethyl acetate from complex matrices (Taiwanese millet wine and whiskey) for immediate IM-MS analysis. An isotopically labeled internal standard was used to compensate for drift time and intensity shifts across multiple analyses. The system operates automatically with a graphical user interface enabling immediate ion-mobility spectrum visualization for targeted <i>m</i>/<i>z</i>.