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Simultaneous Detection of Copper, Lead and Mercury in River Water with In-Situ pH Control Using Electrochemical Stripping Techniques

preprint
submitted on 30.07.2020 and posted on 31.07.2020 by Bernardo Patella, Benjamin O'sullivan, Robert Daly, Pierre Lovera, Rosslinda Inguanta, Alan O'Riordan

ABSTRACT: An electrochemical sensor for the detection of lead, mercury and copper in neutral solutions is described. The electrode is made of two distinct parallel gold interdigitated microband electrodes that can be polarized separately. Biasing one electrode “protonator” sufficiently positive to begin water electrolysis, results in the production of H+ ions which consequently drops the pH in the locality around the other second interdigitated “sensing” electrode. This decrease in pH permits the electodeposition (and consequent stripping) of metals at the sensing electrode without the need to acidify the whole test solution. In this work, the local pH can be adjusted from 1 to 7 in a stable and reproducible way by tailoring the applied potential to the protonator electrode. Using this approach, linear ranges for lead 10-100 ppb, copper 5-100 ppb and mercury 1-75 ppb, respectively were demonstrated which exhibit extremely high sensitivity. This technique allowed detection of these metals in a complex water matrix (river water) without sample pretreatment, with excellent results. The electrode reproducibility is high (RSD < 10%) and the metals can be co-detected when present all together. This is the first demonstration of the in-situ pH control for heavy metal detection using solid state sensors and will unable real time and in situ analysis of heavy metals by unskilled personnel in remote settings.

Funding

UisceSense Project (Code: 2015-W-MS-21)

VistaMilk Center Science Foundation Ireland (SFI) and Department of Agriculture Food and the Marine (DAFM) under Grant Number 16/RC//3835

History

Email Address of Submitting Author

alan.oriordan@tyndall.ie

Institution

Tyndall National Institute

Country

Ireland

ORCID For Submitting Author

0000-0002-7554-1536

Declaration of Conflict of Interest

No COI

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