Coulometric Calcium Pump for Thin Layer Sample Titrations

Majid Ghahraman Afshar; Gaston A Crespo; Eric Bakker

doi:10.1021/acs.analchem.5b02856

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Coulometric Calcium Pump for Thin Layer Sample Titrations

Journal article

Peer reviewed

Coulometric Calcium Pump for Thin Layer Sample Titrations

Majid Ghahraman Afshar, Gaston A Crespo and Eric Bakker

Analytical Chemistry, Vol.87(19), pp.10125-10130

2015

DOI: https://doi.org/10.1021/acs.analchem.5b02856

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Abstract

Analytical Chemistry

Chemical Engineering

Other Chemical Sciences

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.

Details

Title: Coulometric Calcium Pump for Thin Layer Sample Titrations
Authors: Majid Ghahraman Afshar (Author) - University of Geneva, Switzerland
Gaston A Crespo (Author) - University of Geneva, Switzerland
Eric Bakker (Author) - University of Geneva, Switzerland
Publication details: Analytical Chemistry, Vol.87(19), pp.10125-10130
Publisher: American Chemical Society
Date published: 2015
DOI: 10.1021/acs.analchem.5b02856
ISSN: 0003-2700
Organisation Unit: University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99449127802621
Output Type: Journal article

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