We present a chemical ionization quadrupole mass spectrometer (CI-QMS) with a novel discharge ion source. In addition to the expected detection of PAN, peracetic acid and ClNO₂, the instrument is also sensitive to SO₂, HCl and acetic acid through ion chemistry unique for our ion source. We present ionization schemes along with illustrative datasets from field campaigns underlining the potential of the CI-QMS as an alternative to polonium, especially for application in the marine boundary layer.