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Coulometric Calcium Pump for Thin Layer Sample Titrations

Published in Analytical Chemistry. 2015, vol. 87, no. 19, p. 10125-10130
Abstract A selective electrochemical calcium pump based on a fast diffusive calcium ionophore-based membrane is reported. An initially nonpolarized ionophore-based membrane allows one to establish a net calcium flux by applying a potential step function (i.e., 250 mV for 30 s). The resulting calcium flux is released into a microliter scale thin layer reservoir, and the resulting ion perturbation is monitored by either a potentiometric or a coulometric readout. This chemical perturbation in the thin layer thus acts as a titration agent that is precisely controlled by coulometry. A linear correlation between released and detected calcium is confirmed by the two different readout modes. Having demonstrated the efficiency of the calcium pump in background electrolyte solutions, a complexometric titration with known concentrations of EDTA in the thin layer sample was performed. With the potentiometric readout, titrations in the range of 0.25−0.75 mM gave a precision of 3%, whereas the coulometric readout gave a range of 0.02−0.12 mM and a precision of 2%. Improved precision is expected by better control of the thin layer geometry by microfabrication. The significance of this work is that the coupling of a selective calcium pump with a thin layer element can give rise to rapid and complete sample concentration changes and result in a promising platform for titrations either on the laboratory bench or for in situ measurements in environmental or diagnostic settings.
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Research group Groupe Bakker
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GHAHRAMAN AFSHAR, Majid, CRESPO PARAVANO, Gaston Adrian, BAKKER, Eric. Coulometric Calcium Pump for Thin Layer Sample Titrations. In: Analytical Chemistry, 2015, vol. 87, n° 19, p. 10125-10130. doi: 10.1021/acs.analchem.5b02856 https://archive-ouverte.unige.ch/unige:75926

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Deposited on : 2015-10-12

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