Ion exchange voltammetry as a versatile technique for selective determination of target analytes using novel organicploymers and functionalized clay materials
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Date
2018
Authors
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Publisher
Department of Chemistry
Abstract
A voltammetric sensor for both the individual and the simultaneous determination of ascorbic
acid (AA), uric acid (UA) and folic acid (FA) is described. It is based on a glassy carbon
electrode (GC) that was modified with bentonite (Bt) that was first functionalized with cysteine
(Cys) to which gold nanoparticles were linked. The resulting material (referred to as Au-Cys-Bt)
and the other materials were characterized by UV-vis spectroscopy, powder X-ray diffraction
(XRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron
spectroscopy (XPS), energy dispersive X-ray analysis and electrochemical methods. The XRD
peak positions of bentonite and Cys-functionalized bentonite prove the incorporation of Cys into
bentonite. The XPS spectrum of Au-Cys-Bt confirms the interaction of gold nanoparticles with
the thiol group of Cys. The modified GC displays high electrocatalytic activity for the oxidation
of AA, UA and FA, typically at 0.19, 0.41, and 0.73 V (vs. SCE), respectively. Differential pulse
voltammetric data show a linear response that covers the 1 μM to 25 mM concentration range for
AA, the 1 to 200 μM concentration range for UA, and two linear ranges for FA, one from 5 to
100 μM and one from 100 μM to 1.5 mM. The sensor was applied to the determination of AA,
UA and FA in (spiked) multi-vitamin syrup, bird serum and milk samples.
Description
Ion Exchange Voltammetry
Keywords
Ion Exchange Voltammetry, Functionalized Clay Materials