Detection Of Trace Heavy Metal Ions By Anodic Stripping Voltamettry Using L-Cysteine Functionalized Carbon Nanotubes Paste Electrode
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Date
2012-05
Authors
Tan, Chin Wei
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The development and application of the L-cysteine functionalized carbon nanotubes paste electrode (Cys-CNTPE) biosensor for the detection of lead ion (Pb2+) and cadmium ion (Cd2+) in the aqueous system are described. L-cysteine was covalently attached to multi-walled carbon nanotubes (MWCNTs) via N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide-N-hydroxysuccinimide (EDC-NHS) carbodiimide coupling as a recognition element for its high metal-chelating ability towards Pb2+ and Cd2+. The covalent attachment of L-cysteine on MWCNTs was verified with the results from Fourier Transform Infrared Spectroscopy (FTIR) characterization. The Cys-CNTPE was prepared by dispersing the L-cysteine functionalized multi-walled carbon nanotubes (Cys-MWCNTs) into mineral oil and then firmly packed into the well of an electrode. Determination of Pb2+ and Cd2+ at the Cys-CNTPE were evaluated by Differential Pulse Anodic Stripping Voltammetry (DPASV). Prior to the analysis, accumulation of Pb2+ and Cd2+ at the Cys-CNTPE proceeded with constant stirring for a specific duration of time. The resulting stripping peak currents and peak positions were correlated to the concentrations and types of heavy metal ions, respectively. From the voltammetry analysis of Pb2+ and Cd2+, the Cys-CNTPE showed significantly enhanced sensitivity and selectivity, attributable to the synergistic combination of the recognition properties of L-cysteine and the excellent electrical properties of MWCNTs. Optimization of the experimental parameters was performed in order to obtain the best sensitivities for the determination of Pb2+ and Cd2+ at the Cys-CNTPE, in which the effect of accumulation time, reduction potential, reduction time, pH of acetate buffer solution and electrode paste composition were investigated.
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Keywords
Detection of trace heavy metal ions , by anodic stripping voltamettry