Inkjet Printed Multi-Walled Carbon Nanotube Sensor for the Detection of Lead in Drinking Water

摘要

The heavy metal lead has been a pollutant in our environment for many centuries and at low concentrations, lead can damage the human central nervous system, liver, kidney, and cardiovascular system and cause physiological and neurological problems in developing children who are most susceptible to lead poisoning. Lead in drinking water is currently regulated in the United States by the Environmental Protection Agency (EPA) with a maximum contamination level (MCL) of 15 ppb and the World Health Organization (WHO) has a MCL of 10 ppb of lead. Researches have identified high levels of lead in drinking water samples across the globe and the neurological development of young children is of great concern. A need for a rapid, sensitive, selective, reproducible, and affordable sensor for the trace detection of lead in true drinking water samples is needed. The detection of Pb~(2+) was performed using an inkjet printed multi-walled carbon nanotube (IJP-MW-CNT) electrode employing Osteryoung square wave stripping voltammetry (OSWV) as the detection method. The MW-CNT ink was prepared in water using bile salts (BS) as a surfactant, which were washed out extensively with DI water before using the printed MW-CNTs as electrodes. The IJP-MW-CNT electrode was used as the working electrode with a platinum wire and glass capillary Ag/AgCl as auxiliary and reference electrode, respectively. The electrodes performance was optimized in 0.1 M acetate buffer (pH = 4.3) and had a linear range of 5 - 50 ppb (R~2 = 0.98235) a sensitivity of 20.15 nA/ppb and a limit of detection (LOD) of 1.632 ppb for Pb~(2+). The analytical applicability of electrode was tested in a real drinking water sample (i.e.) Cincinnati tap water with a linear range of 15 - 70 ppb (R~2 = 0.98752) a sensitivity of 2.654 nA/ppb and a LOD of 1.269 ppb for Pb~(2+). The IJP-MW-CNT electrode's results are comparable between different electrodes, and reproducible using the same electrode multiple times. The electrode can be easily and quickly be fabricated without modifications or in-situ additives needed, which makes up-scale production a feasible option. The sensor has been shown to perform well in an environmental sample (Cincinnati tap water) without any sample preparation or changes. The IJP-MW-CNT electrode can be implemented for the affordable and rapid detection of lead on-site in true water samples.