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 oxo-anions (XO3-) 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 ClO3-, BrO3-, and IO3- in methanolic solution.