High-Sensitivity Analysis of Polycyclic Aromatic Hydrocarbons by Nanodroplet Interfacial Ionization Coupled with Mass Spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are well-known environmental pollutants with significant carcinogenic potential. The detection of PAHs by mass spectrometry (MS) remains challenging due to their trace contents and extremely low ionization efficiency. The emerging microdroplet-based MS techniques utilize interfacial reactions for the acceleration of chemical reactions and improvement of ionization efficiency, thereby offering high selectivity and sensitivity for complex samples. In this study, we present a novel nanodroplet interfacial ionization (NII) technique that achieved direct detection of PAHs in complex biological samples with high sensitivity at attomole (amol) level. It significantly increased the ionization efficiency of PAHs by converting them into radical cations (M^•+) through interfacial reactions at the surfaces of nanodroplets. The effectiveness of NII for the ionization of PAHs was confirmed by the analysis of a wide range of PAHs and their derivatives. The practicality of NII was further demonstrated by its application in the analysis of trace PAHs and related metabolites in single mammalian cells. NII holds great potential in environmental studies on the toxicological effects of aromatic pollutants. Furthermore, it might also be beneficial to research studies in the activation of aromatic rings for chemical synthesis.