Δευτέρα 12 Ιουνίου 2017

Design and development of amperometric biosensor for the detection of lead and mercury ions in water matrix—a permeability approach

Abstract

Intake of water contaminated with lead (Pb2+) and mercury (Hg2+) ions leads to various toxic effects and health issues. In this context, an amperometric urease inhibition-based biosensor was developed to detect Pb2+ and Hg2+ ions in water matrix. The modified Pt/CeO2/urease electrode was fabricated by immobilizing CeO2 nanoparticles and urease using a semi-permeable adsorption layer of nafion. With urea as a substrate, urease catalytic activity was examined through cyclic voltammetry. Further, maximum amperometric inhibitive response of the modified Pt/CeO2/urease electrode was observed in the presence of Pb2+ and Hg2+ ions due to the urease inhibition at specific potentials of −0.03 and 0 V, respectively. The developed sensor exhibited a detection limit of 0.019 ± 0.001 μM with a sensitivity of 89.2 × 10−3 μA μM−1 for Pb2+ ions. A detection limit of 0.018 ± 0.003 with a sensitivity of 94.1 × 10−3 μA μM−1 was achieved in detecting Hg2+ ions. The developed biosensor showed a fast response time (<1 s) with a linear range of 0.5–2.2 and 0.02–0.8 μM for Pb2+ and Hg2+ ions, respectively. The modified electrode offered a good stability for 20 days with a good repeatability and reproducibility. The developed sensor was used to detect Pb2+ and Hg2+ ions contaminating Cauvery river water and the observed results were in good co-ordination with atomic absorption spectroscopic data.



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