Novel Speciation Method Based on Diffusive Gradients in Thin-Films for in Situ Measurement of Cr<sup>VI</sup> in Aquatic Systems


Hexavalent chromium (Cr<sup>VI</sup>) is much more toxic and mobile than the trivalent species (Cr<sup>III</sup>) and consequently, in situ monitoring of Cr<sup>VI</sup> can improve the understanding of Cr biogeochemistry and toxicity in ecosystems. The passive diffusive gradients in thin-films (DGT) technique is a powerful tool for determining metal­(loid) speciation, but a binding phase that absorbs only one specific species of Cr is needed. <i>N</i>-Methyl-d-glucamine (NMDG) functional resin was incorporated into the DGT binding phase for selective measurement of Cr<sup>VI</sup>. This NMDG-DGT sampler exhibited a theoretically linear accumulation of Cr<sup>VI</sup>, with negligible accumulation (<5%) of Cr<sup>III</sup>, even after 72 h deployment. The good prediction of Cr<sup>VI</sup> concentration in synthetic freshwater with NMDG-DGT, even in the presence of 10-time more Cr<sup>III</sup>, further indicated the sampler’s reliability in selective detection of Cr<sup>VI</sup>. Moreover, its high capacity for Cr<sup>VI</sup>, which exceeded 230 μg cm<sup>–2</sup>, facilitates measurement of Cr<sup>VI</sup> in both uncontaminated natural waters and in slightly and heavily contaminated (ppm level) waters. Field deployment of the NMDG-DGT sampler in such waters allowed accurate measurement of time-averaged Cr<sup>VI</sup> concentration, indicating its robustness for in situ measurements of Cr speciation and its potential for further application in the risk assessment of Cr

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oai:figshare.com:article/2099443Last time updated on 2/12/2018

This paper was published in FigShare.

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