Speciated isotope dilution analysis of Cr(III) and Cr(VI) in water by ICP-DRC-MS

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

21 Scopus Citations
View graph of relations

Author(s)

  • H. L. Ma
  • P. A. Tanner

Detail(s)

Original languageEnglish
Pages (from-to)189-194
Journal / PublicationTalanta
Volume77
Issue number1
Publication statusPublished - 19 Oct 2008

Abstract

An isotope dilution method has been developed for the speciation analysis of chromium in natural waters which accounts for species interconversions without the requirement of a separation instrument connected to the mass spectrometer. The method involves (i) in-situ spiking of the sample with isotopically enriched chromium species; (ii) separation of chromium species by precipitation with iron hydroxide; (iii) careful measurement of isotope ratios using an inductively coupled plasma mass spectrometer (ICP-MS) with a dynamic reaction cell (DRC) to remove isobaric polyatomic interferences. The method detection limits are 0.4 μg L-1 for Cr(III) and 0.04 μg L-1 for Cr(VI). The method is demonstrated for the speciation of Cr(III) and Cr(VI) in local nullah and synthetically spiked water samples. The percentage of conversion from Cr(III) to Cr(VI) increased from 5.9% to 9.3% with increase of the concentration of Cr(VI) and Cr(III) from 1 to 100 μg L-1, while the reverse conversion from Cr(VI) to Cr(III) was observed within a range between 0.9% and 1.9%. The equilibrium constant for the conversion was found to be independent of the initial concentrations of Cr(III) and Cr(VI) and in the range of 1.0 (at pH 3) to 1.8 (at pH 10). The precision of the method is better than that of the DPC method for Cr(VI) analysis, with the added bonuses of freedom from interferences and simultaneous Cr(III) determination. © 2008 Elsevier B.V. All rights reserved.

Research Area(s)

  • Chromium, Dynamic reaction cell, ICP-MS, Natural waters, Precipitation method, Speciated isotope dilution, Speciation

Citation Format(s)

Speciated isotope dilution analysis of Cr(III) and Cr(VI) in water by ICP-DRC-MS. / Ma, H. L.; Tanner, P. A.

In: Talanta, Vol. 77, No. 1, 19.10.2008, p. 189-194.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review