Synergistic Ionization via Plasma-Droplet Coupling in an LTP-DESI Hybrid Source for Sensitive Analysis of Volatile Aroma Compounds

Rapid and sensitive detection of volatile compounds in complex matrices remains challenging due to limited ionization efficiency. Herein, we developed a novel hybrid ionization source by coaxially integrating low-temperature plasma with desorption electrospray ionization (LTP-DESI). The LTP-DESI hybrid source was equipped with a triple quadrupole mass spectrometer to analyze volatile aroma compounds. Under the LTP-DESI mode, volatile aroma compounds exhibited significant signal enhancements, with intensities increased by up to 2 orders of magnitude compared with DESI or LTP. This enhancement arises from a three-stage synergistic mechanism: (1) droplet and plasma-driven desorption, (2) primary ionization by both charged droplets and plasma species, and (3) synergistic ionization enhancement via plasma–droplet interaction. The spatial and temporal overlap of the charged droplet and plasma plume significantly promotes [M + H]+ generation through Penning ionization, proton transfer and charge exchange under atmospheric pressure. The quantitative and qualitative capability of the LTP-DESI-MS platform was validated through analyses of commercial perfumes and banana tissues, achieving recoveries of 75.3–108.5% with relative standard deviations of 2.7–17.1%. These results highlight the potential of the LTP-DESI system as a robust, practical technique for rapid ambient analysis of aromas in diverse complex samples.