Rapid and sensitive detection of polycyclic aromatic hydrocarbons using electrochemically assisted derivatization mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous toxic pollutants that pose significant risks to human health. However, because of their intrinsic non-polar properties, only moderate detection sensitivity can be achieved in the mass spectrometric detection of PAHs. In this work, we presented a novel electrochemically assisted derivatization nano-electrospray ionization mass spectrometry (ECAD-nESI-MS) method to permit the rapid and ultrasensitive analysis of PAHs in complicated samples. In ECAD-nESI-MS, the in situ electrochemical derivatization of PAHs with pyridine and the electrospray ionization are simultaneously activated by applying a high voltage onto the Pt electrode. Notably, the derivatization takes advantage of the inherent electrochemical aspect of electrospray ionization, that is, the electrooxidation of substrates in the positive-ion mode, thus requiring no extra electrochemical cell and potentiostat. Through the electrochemical derivatization of PAHs into the corresponding pyridinium ions, the ECAD-nESI-MS method achieved remarkably improved detection sensitivity, where the limit of detection (LOD) is 3~10 times lower than the state-of-the-art atmospheric pressure chemical ionization mass spectrometry (APCI-MS) and gas chromatography mass spectrometry (GC-MS). With advantages in low detection limit, wide linear range, fast analysis speed (< 3 min per sample), and low sample consumption, we anticipate the wide application of the ECAD-nESI-MS method in the rapid and sensitive analysis of PAHs and their analogues. Graphical abstract