GEMMA: a Gel-based Electrochemical sensor for the Measurement of Metal Availability in solution
Abstract
RationaleUnderstanding speciation dynamics of trace metal elements (TMEs) is essential for assessing their environmental behavior and biological impacts. Time-integrated sensors represent one of the most effective approaches for detecting free metal ions and labile metal complexes in natural waters.
MethodologyIn this work, mercury-free and cost-effective Gel-based Electrochemical sensor for the Measurement of Metal Availability (GEMMA) is here introduced. The device consists of a lab-made screen-printed electrode comprising the carbon counter electrode and the working electrode using Bismuth as the sensing element, overlaid with a diffusion-controlled agarose hydrogel layer. By leveraging the diffusion-driven transport of metal species, encompassing free ions and small complexes diffusion through the hydrogel and their accumulation at the electrode, GEMMA enables the quantification of free and labile metal concentrations in solution based on the amount collected over a defined deposition time. This study focuses on the preparation and optimization of a Bismuth-film electrode for the sensitive detection of Pb(II) at nanomolar levels using Stripping Chronopotentiometry (SCP).
ResultsKey aspects include electrochemical performance evaluation through Pb(II) calibrations and comparative analysis in the presence and absence of the hydrogel layer. Additionally, an exploratory speciation work examines Pb availability in the presence of a molecular ligand, offering insights into metal lability diagnosis and its implications for bioavailability in natural aquatic environments or laboratory-scale experiments.
DiscussionThe GEMMA device demonstrates reliable Pb(II) speciation, though challenges like Bi surface oxidation at near-neutral pH and gel equilibration times remain. Future work will focus on refining electrode pre-treatments, exploring broader ligand Moussaoui EN26059 2 interactions, and coupling GEMMA with complementary techniques (e.g., AGNES for free metal quantification) to enhance accuracy in complex aquatic environments.
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BibTeX
@article{moussaoui2026gemma,
title = {{GEMMA: a Gel-based Electrochemical sensor for the Measurement of Metal Availability in solution}},
author = {Rima Moussaoui and Renaud Gley and Clément Bojic and José Paulo Pinheiro and Elise Rotureau},
journal = {Environmental Chemistry},
year = {2026},
month = oct,
url = {https://hal.univ-lorraine.fr/hal-05840893v1},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - JOUR
TI - GEMMA: a Gel-based Electrochemical sensor for the Measurement of Metal Availability in solution
AU - Rima Moussaoui
AU - Renaud Gley
AU - Clément Bojic
AU - José Paulo Pinheiro
AU - Elise Rotureau
PY - 2026
DA - 2026/10/23
JO - Environmental Chemistry
UR - https://hal.univ-lorraine.fr/hal-05840893v1
AB - RationaleUnderstanding speciation dynamics of trace metal elements (TMEs) is essential for assessing their environmental behavior and biological impacts. Time-integrated sensors represent one of the most effective approaches for detecting free metal ions and labile metal complexes in natural waters. MethodologyIn this work, mercury-free and cost-effective Gel-based Electrochemical sensor for the Measurement of Metal Availability (GEMMA) is here introduced. The device consists of a lab-made screen-printed electrode comprising the carbon counter electrode and the working electrode using Bismuth as the sensing element, overlaid with a diffusion-controlled agarose hydrogel layer. By leveraging the diffusion-driven transport of metal species, encompassing free ions and small complexes diffusion through the hydrogel and their accumulation at the electrode, GEMMA enables the quantification of free and labile metal concentrations in solution based on the amount collected over a defined deposition time. This study focuses on the preparation and optimization of a Bismuth-film electrode for the sensitive detection of Pb(II) at nanomolar levels using Stripping Chronopotentiometry (SCP). ResultsKey aspects include electrochemical performance evaluation through Pb(II) calibrations and comparative analysis in the presence and absence of the hydrogel layer. Additionally, an exploratory speciation work examines Pb availability in the presence of a molecular ligand, offering insights into metal lability diagnosis and its implications for bioavailability in natural aquatic environments or laboratory-scale experiments. DiscussionThe GEMMA device demonstrates reliable Pb(II) speciation, though challenges like Bi surface oxidation at near-neutral pH and gel equilibration times remain. Future work will focus on refining electrode pre-treatments, exploring broader ligand Moussaoui EN26059 2 interactions, and coupling GEMMA with complementary techniques (e.g., AGNES for free metal quantification) to enhance accuracy in complex aquatic environments.
SN - 1448-2517
SN - 1449-8979
ER -