Marcinek, Saša, Chapoulie, Arnaud, Salaün, Pascal 
ORCID: 0000-0001-9525-3382, Smith, Scott and Omanović, Dario
(2021)
Revised application of copper ion selective electrode (Cu-ISE) in marine waters: A new meta-calibration approach.
Talanta, 226.
p. 122170.
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TAL-D-20-04432_R2_AuthorAcceptedVersion.pdf - Author Accepted Manuscript Download (9MB) | Preview |
Abstract
Copper (Cu) is a bio-essential trace element that is of concerns due to its potential toxicity at concentrations commonly encountered in coastal waters. Here, we revisit the applicability of Cu(II) ion selective electrode (Cu-ISE) based on a jalpaite membrane for the measurement of Cu<sub>free</sub> in seawater. At high total Cu concentration (>0.1 mM), (near)Nernstian slope was obtained and determination of Cu<sub>free</sub> down to fM levels was possible. However, this slope decreases with decreasing total Cu concentration (e.g. 7 mV/decade at 15 nM total Cu) making the use of a common single calibration approach unreliable. To solve this problem, we carried out several calibrations at different levels of total Cu (15 nM - 1 mM) and ethylenediamine (EN: 5 μM - 15 mM) and fitted the calibration parameters (slope and intercept) as a function of total Cu using the Gompertz function (a meta-calibration approach). The derived empirical equations allowed the determination of Cu<sub>free</sub> at any total Cu concentration above 20 nM (determination of Cu<sub>free</sub> at lower total Cu levels is prevented by the dissolution of the electrode). We successfully tested this meta-calibration approach in UV digested seawater in presence of a synthetic ligand (EN), isolated natural organic matter (humic acid, HA) and in a natural estuarine sample. In each case, our meta-calibration approach provided a good agreement with modeled speciation data (Visual MINTEQ), while standard single approach failed. We provide here a new method for the direct determination of the free Cu ion concentration in seawater at levels relevant for coastal waters.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Copper ion selective electrode, meta-Calibration, Speciation, Trace metals |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 24 Feb 2021 17:02 |
| Last Modified: | 10 Mar 2023 16:48 |
| DOI: | 10.1016/j.talanta.2021.122170 |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3115944 |
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