Inhibitive Determination of Metal Ions Using a Horseradish Peroxidase Amperometric Biosensor

Abstract

The development of electro-analytical methods for the determination of mercury, lead, cadmium and various other trace metals in acidic media or at different pH values are not new and for that reason, the investigation of alternative techniques have been ongoing and especially to find mercury-free electrodes (Ugo et al., 1995). Stripping voltammetry has been widely used for trace metal analysis with mercury as the working electrode due to its remarkable analytical properties. However, due to the toxicity of mercury and the human health risk that it poses (bioaccumulation in the food chain), there have been in‐ sistent efforts to remove the use of mercury completely. Electroanalysis has therefore seen the use of mercury-free sensors, while much attention has been dedicated to the develop‐ ment of such sensors over the last decade (Hwang et al., 2008; Sonthalia et al., 2004). Sev‐ eral heavy metals create environmental and human health concerns when elevated concentrations of these metals are present in the environment. In this regard, lead (Pb) and mercury (Hg) and more increasingly cadmium (Cd) heavy metals are of prime envi‐ ronmental concern, since they are significant for environmental surveillance, food control, occupational medicine, toxicology and hygiene (Ensafi and Zarei, 2000). Lead (Pb) is fur‐ thermore constantly monitored in natural and drinking water due to the harmful effects that are often manifested in young children (Zen et al., 2002). It is also known that several trace metals are regarded as essential micro-nutrients and play an integral role in the life processes of living organisms. In contrast, metals such as aluminium, silver, cadmium, gold, lead and mercury play no biological role in living organisms and lead to toxicity