Determination of Sulfur Compounds in Water Samples by Ion Chromatography Dynamic Reaction Cell Inductively Coupled Plasma Mass Spectrometry

An ion chromatography‐inductively coupled plasma mass spectrometric (IC‐ICP‐MS) method for the speciation of sulfur compounds, namely sulfite SO₃^2?], sulfate SO₄^2?] and thiosulfate S₂O₃^2?], was described. Ionic sulfur compounds were well separated in about 3 min by ion chromatography with a Hamilton PRP‐X100 column as the stationary phase and 60 mmol L^?1 NH₄NO₃ and 0.1% v/v formaldehyde (HCHO) solution (pH = 7) as the mobile phase. The analyses were carried out using dynamic reaction cell (DRC) ICP‐MS. The sulfur‐selective chromatogram was determined at m/z 48 as ³²S¹⁶O⁺ by using its reaction with O₂ in the reaction cell. The method avoided the effect of polyatomic isobaric interferences at m/z 32 caused by ¹⁶O¹⁶O⁺ and ¹⁴N¹⁸O⁺ on ³²S⁺ by detecting ³²S⁺ as the oxide ion ³²S¹⁶O⁺ at m/z 48, which is less interfered. The detection limit of various species studied was in the range of 3.6–4.6 ng S mL^?1. The accuracy of the method has been verified by comparing the sum of the concentrations of individual sulfur compounds obtained by the present procedure with the total concentration of sulfur in several natural water samples. The recovery was in the range of 97–102% for various compounds studied.