Identification and quantification of chloramines, bromamines and bromochloramine by Membrane Introduction Mass Spectrometry (MIMS)

Wei Hu; Frants Roager Lauritsen; Sébastien Allard

doi:10.1016/j.scitotenv.2020.142303

Identification and quantification of chloramines, bromamines and bromochloramine by Membrane Introduction Mass Spectrometry (MIMS)

Sci Total Environ. 2021 Jan 10:751:142303. doi: 10.1016/j.scitotenv.2020.142303. Epub 2020 Sep 11.

Authors

Wei Hu¹, Frants Roager Lauritsen², Sébastien Allard³

Affiliations

¹ Curtin Water Quality Research Centre, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia.
² Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Denmark.
³ Curtin Water Quality Research Centre, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia. Electronic address: s.allard@curtin.edu.au.

PMID: 33182003
DOI: 10.1016/j.scitotenv.2020.142303

Abstract

A Membrane Introduction Mass Spectrometry (MIMS) method was developed to differentiate and quantify the different chlorinated and brominated-amines, present in drinking water during chloramination. The representative mass to charge ratios (m/z) of 53, 85, 97, 175 and 131 corresponding to the mass of the parent compounds were selected to monitor NH₂Cl, NHCl₂, NH₂Br, NHBr₂ and NHBrCl and the detection limits were found to be 0.034, 0.034, 0.10, 0.12 and 0.36 mg/L as Cl₂, respectively. NHCl₂, NHBr₂ and NHBrCl fragments interfere with the analysis/quantification of NH₂Cl and NH₂Br via protonation reactions at hot metal surfaces inside the mass spectrometer. To accurately quantify NH₂Cl or NH₂Br in mixtures of NH₂Cl/NHCl₂ or NH₂Br/NHBr₂, the interference from NHCl₂ or NHBr₂ was subtracted to the signal of the parent compound. If NHBrCl is present, NH₂Br and NH₂Cl cannot be accurately quantified since the interference from the NHBrCl fragment cannot be distinguished from the signal of the parent compound. Under drinking water conditions, the interference from NHBrCl on NH₂Cl was negligible. The different halamines were monitored and quantified for the first time in two surface waters and one seawater that were chloraminated to mimic a realistic disinfection scenario.

Keywords: Bromamine; Chloramine; Disinfection; Drinking water; Membrane Introduction Mass Spectrometry; Oxidation.