Determination of Parts-per-Trillion Levels of Chlorate, Bromate, and Iodate by Electrospray Ionization/High-Field Asymmetric Waveform Ion Mobility Spectrometry/Mass Spectrometry

An electrospray ionization (ESI) source was used to transfer oxoanions (XO 3 − ) of nitrogen, chlorine, bromine, and iodine to the gas phase for analysis by a combination of high-field asymmetric waveform ion mobility spectrometry (FAIMS) and mass spectrometry. The combination of ESI with FAIMS and mass spectrometry (ESI-FAIMS-MS) yields mass spectra that are virtually free of common spectral interferences. The unique separation and focusing properties of the FAIMS analyzer improved signal-to-background ratios (S/B) for all these analytes by 3–4 orders of magnitude compared with conventional ESI-MS and produced parts-per-trillion (pptr) detection limits for ClO 3 − , BrO 3 − , and IO 3 − in methanolic solution.