CHROMIUM SPECIATION IN BACTERIAL CULTURE MEDIUM BY COMBINING STRONG ANION EXCHANGE LIQUID CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY. APPLICATION TO THE REDUCTION OF CR(VI) BY SULFATE-REDUCING BACTERIA

Abstract

Because of its toxicity, Cr(VI) contamination constitutes a major environmental problem. Reduction of Cr(VI) to Cr(III) by sulfate-reducing bacteria is accordingly a promising biotechnology. Developing this will require research to select the most efficient bacteria and to study the precise mechanism of reduction involved. We have, therefore, adapted an analytical method that combines high-performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP-MS), allowing the speciation of Cr(VI) and Cr(III) in complex medium. This method permits simultaneous determination of both species with high sensitivity and specificity. Applied to the Cr(VI) reduction by the sulfate-reducing bacteria Desulfomicrobium norvegicum, it has allowed a preliminary conclusion that the reduction is biphasic and occurs before replication of the bacteria.

ACKNOWLEDGMENTS

One of the authors (B. Chardin) gratefully acknowledges receipt of a CIFRE research studentship from S.E.I Environnement et Procédés Industriels. We also thank Professor J.C. Sari for helpful discussions and valuable criticisms.