Detection of Cadmium using Conjugated Polymer Modified Electrodes
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Detection of Cadmium using Conjugated Polymer Modified Electrodes Timothy Ponrathnam1, Seth Robertson2, Junghwan Cho2, Pradeep Kurup2 & Ramaswamy Nagarajan1 1
Department of Plastics Engineering, University of Massachusetts Lowell, MA 01854, U.S.A.
2
Department of Civil and Environmental Engineering, University of Massachusetts Lowell, MA
01854, U.S.A. ABSTRACT The detection of heavy metals in subsurface strata currently requires tedious sampling procedures followed by laboratory analysis using techniques such as atomic absorption spectroscopy (AAS) or inductively couple plasma atomic emission spectroscopy (ICP-AES). These techniques are extremely accurate and capable of detecting very low concentrations of metal ions. The main drawback of these techniques is that they are time consuming, expensive to perform and not portable. A portable sensor capable of detecting metals ion in solution is highly desirable. Anodic Stripping Voltammetry (ASV) can be utilized as a reliable method for the trace detection of metal ions in water. In order to improve the sensitivity of the electrochemical sensor, conjugated polymer films can be coated on the surface of the glassy carbon working electrodes. Stable films of poly (3,4 ethylenedioxythiophene) [PEDOT] and polythiophene copolymer [PTCPTA] were electrochemically synthesized on the surface of a glassy carbon electrode. These polymer modified electrodes were utilized for the detection of cadmium in water. The sensors are capable of detecting trace concentrations of cadmium approaching the maximum contamination limits imposed by the Environment Protection Agency (EPA). INTRODUCTION Under the aegis of the Clean Water Act (CWA) and Safe Drinking Water Act (SDWA), regulatory standards for inorganic contaminants have been set by the U.S. EPA. The maximum contamination level (MCL) of cadmium (Cd2+) has been established as 5 parts per billion (ppb) [1]. Long-term exposure above the MCL to this metal can result in kidney or liver damage. Most of the Cd2+ groundwater contamination is a direct result of anthropogenic activities. This may include corrosion of buried pipes over time, deterioration of underground storage tanks and improper disposal of electronics (particularly from batteries and battery waste). Typical laboratory techniques for qualitative and quantitative detection of heavy metal contaminants in water include atomic absorption spectroscopy (AAS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and x-ray florescence spectroscopy (XRF) [2]. While these methods do provide highly accurate detection of many dissolved heavy metals at levels below the MCL, they also prove costly, time consuming, and laborious. This necessitates investigation of alternate methodologies for in-situ heavy metal detection. Several metal ion contaminants such as cadmium, lead, mercury and zinc are electroactive. Thus voltammetry may be investigated as a low cost, portable technique for the detection of these metal contaminants. Voltammetry is the study of current (I) resulting due t
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