Simultaneous Detection of Polar and Nonpolar Molecules by Nano-ESI MS with Plasma Ignited by an Ozone Generator Power Supply

We present a simple and cost-effective method for generating a dielectric barrier discharge (DBD) plasma using a commercially available ozone generator power supply. By coupling the plasma source to the extended ion transfer tube of an ambient mass spectrometer, we achieved stable plasma discharge, enabling the post-ionization of nonpolar compounds during the electrospray ionization process. Using this approach, we successfully detected polycyclic aromatic hydrocarbons (PAHs), halogenated PAHs (HPAHs), and other nonpolar pollutants in liquid mixtures, with detection limits on the order of 10 ng/mL. In fish exposed to HPAHs, both polar metabolites and lipids, as well as the nonpolar pollutant 1-chloronaphthalene, were simultaneously detected. Notably, 1-chloronaphthalene accumulated at the highest concentration in gill tissue. This straightforward plasma-assisted technique offers a reliable strategy for expanding the detection capabilities of electrospray mass spectrometry to include nonpolar molecules.