Electrospray Ion Chromatography−Tandem Mass Spectrometry of Oxyhalides at Sub-ppb Levels

• Published in: Analytical chemistry (Washington) 1998-01, Vol.70 (2), p.353-359
• Main Authors: Charles, L, Pépin, D
• Format: Article
• Language: English
• Subjects: Analysis; Analytical chemistry; Applied sciences; Chemistry; Chromatographic methods and physical methods associated with chromatography; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; Ions; Other chromatographic methods; Pollution; Scientific imaging; Water treatment and pollution
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac9707186

An electrospray ion chromatography−tandem mass spectrometry (IC-MS/MS) method has been developed for simultaneous analysis of oxyhalide ions (chlorite, chlorate, bromate, iodate) in water. Oxyhalide ions are extracted, from pretreated sample, in solid phase extraction (SPE), using an ion exchange column. Elution with water/methanol ammonium nitrate eluent is performed on-line with negative ion electrospray mass spectrometry detection. Sample pretreatment is required in order to remove any major ions that displace oxyhalides during SPE, consisting of eliminating SO4 2-, Cl-, and HCO3 - with ion exchange resins. Oxyhalide ion fragmentation yields mass spectra with successive oxygen losses. Isotope contribution allows the selection of two precursor ions per analyte (except IO3 -), highly enhancing the selectivity of the method. Eluent ion choice is discussed, particularly because most of the tested ammonium salts were shown to be chlorate contaminated. In water samples, the limits of quantitation are 0.05 (BrO3 - and ClO3 -), 0.5 (IO3 -), and 1.0 μg/L (ClO2 -). In some ammonium salts, the microgram per kilogram level is reached for chlorate impurity quantitation.