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Reagentless and calibrationless silicate measurement in oceanic waters

Giraud, William and Lesven, Ludovic and Jońca, Justyna and Barus, Carole and Gourdal, Margaux and Thouron, Danièle and Garçon, Véronique and Comtat, Maurice Reagentless and calibrationless silicate measurement in oceanic waters. (2012) Talanta, vol. 97. pp. 157-162. ISSN 0039-9140

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Official URL: http://dx.doi.org/10.1016/j.talanta.2012.04.011

Abstract

Determination of silicate concentration in seawater without addition of liquid reagents was the key prerequisite for developing an autonomous in situ electrochemical silicate sensor (Lacombe et al., 2007) [11]. The present challenge is to address the issue of calibrationless determination. To achieve such an objective, we chose chronoamperometry performed successively on planar microelectrode (ME) and ultramicroelectrode (UME) among the various possibilities. This analytical method allows estimating simultaneously the diffusion coefficient and the concentration of the studied species. Results obtained with ferrocyanide are in excellent agreement with values of the imposed concentration and diffusion coefficient found in the literature. For the silicate reagentless method, successive chronoamperometric measurements have been performed using a pair of gold disk electrodes for both UME and ME. Our calibrationless method was tested with different concentrations of silicate in artificial seawater from 55 to 140×10−6 mol L−1. The average value obtained for the diffusion coefficient of the silicomolybdic complex is 2.2±0.4×10−6 cm2 s−1, consistent with diffusion coefficient values of molecules in liquid media. Good results were observed when comparing known concentration of silicate with experimentally derived ones. Further work is underway to explore silicate determination within the lower range of oceanic silicate concentration, down to 0.1×10−6 mol L−1.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com/science/article/pii/S0039914012003062
HAL Id:hal-00879026
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National des Etudes Spatiales - CNES (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
French research institutions > Institut de Recherche pour le Développement - IRD (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS (FRANCE)
Other partners > Université Lille 1, Sciences et Technologies - Lille 1 (FRANCE)
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Deposited By: Vincent GERBAUD
Deposited On:31 Oct 2013 14:23

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