Isotope analysis of sulfur, bromine, and chlorine in individual anionic species by ion chromatography/multicollector-ICPMS

We developed an analytical method for precise and accurate analysis of δ³⁴S, δ⁸¹Br, and δ³⁷Cl in individual anionic species by coupled ion chromatography (IC) and multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The method is based on the online separation and purification of ions by IC prior to their isotope analysis by MC-ICPMS. The developed technique significantly simplifies δ³⁴S, δ⁸¹Br, and δ³⁷Cl analysis in environmental samples. In cases when several anionic species of the same element are present in the sample, they might be analyzed in a single analytical run. Major isobaric interferences for the analyzed elements were reduced by using "dry" plasma conditions and applying sufficient mass resolution power. The sample-standard bracketing technique was used for instrumental drift correction. In the case of δ³⁴S analysis, precisions up to 0.15‰ (1sd) have been achieved for analytes containing down to 5 nmol of S; for δ⁸¹Br, the attained precision was 0.1‰ (1sd) for analytes containing down to 0.6 nmol of Br. Precisions of 0.2‰ have been obtained for δ³⁷Cl with analytes containing 0.7 μmol of Cl. Robustness of the developed analytical method, as well as high precisions and accuracies, has been demonstrated for the laboratory standard solutions and for environmental samples.