Electrochemical Detection of Cd(II) in Environmental Samples Using Nano-Ities

Heavy metals such as cadmium, lead, and arsenic have caused global health concerns that continue to rise yearly, which lead to several harmful diseases that primarily target organs such as kidneys and liver among other vital organs. Because of these well-known harmful effects, regulatory authorities have prescribed “permissible” levels of these metals in food, drinking water, and other possible sources to limit human exposure. However, increasing industrialization and inefficient recycling systems for industrially produced metal wastes have led to an increase in heavy metal exposure to humans. These toxins also bioaccumulate across the food chain, leaving us vulnerable to their harmful effects. Hence it is of great interest to develop systems that can detect metals efficiently to help set up effective metal mitigation protocols. Most conventional metal detecting tools, although highly accurate, require extensive sample pre-treatment steps which alter the speciation of the metal; a critical parameter for determining its toxicity. As(III) is known to be more toxic than As(V) and as such, they have separate medical remedies targeted toward the particular metal species. However, a conventional technique such as ICPMS is unable to differentiate between them. Furthermore, these conventional techniques require equipment that is bulky, expensive, and not user-friendly and limit real-time monitoring. Consequently, the development of a low-cost, portable, and robust sensor capable of providing accurate information on metal speciation will significantly aid in establishing metal mitigation systems efficiently. Low cost and user-friendliness will ensure that the sensor is within the economic and technological reach of most of the population and the portability of the sensor will enable testing in areas that are hard to access via a stationary lab. Such attributes coupled with accurate information on metal speciation will make an ideal metal sensor that will significantly aid the fight against heavy metal exposure. This study uses ion transfer between two immiscible electrolyte solutions (ITIES) to develop a Cd(II) sensor. Electrochemistry at ITIES is less complicated than other electrochemical techniques as it is based on the transfer of ions and does not include redox reactions; making it more attractive. Our electrode is a borosilicate glass electrode that is pulled using a carbon dioxide laser puller with an inner radius of ~300 nm. The nano-scale interface of our