Disposable single-use electrochemical sensor: A novel hollow fiber based tool for environmental monitoring of cadmium

The objective of this study is to design a simple, fast, sensitive and single-use electrode with the simultaneous capability of preconcentration and measuring, for application in a three-electrode voltammetry system to identify and measure the heavy metal cadmium. The design process of this sensor consists of several stages. The polyurethane foam and multi walled carbon nanotubes nanoparticles were functionalized and the new nanocomposite was synthesized that with the help of an organic solvent, established on the pencil graphite electrode that was covered with hollow fiber. In this work, for the first time, the organic solvent was employed instead of ionic liquid. The designed sensor was used to detect and measure heavy metal cadmium through differential pulse voltammetry technique, which appearance of a sharp peak at -0.82 V indicates the presence of cadmium. It was found that the presence of air molecules as the analyte carrier (between hollow fiber cavities and in fixed nanocomposite on the graphite) instead of organic solvents or ionic liquids was desirable. All the synthesis stages of nanocomposite were analyzed by infrared spectroscopy. Finally, the nanocomposite morphology was obtained with a Scanning Electron Microscope. A calibration curve was drawn and linear response with a range of 2.39 to 47.6 µM was plotted. The LOD of the designed sensor was 0.399 µM for cadmium. The mentioned sensor was used to recognize and analyte measurement in real biological samples of urine, nail, and wastewater of the laboratory.