Analysis of Pesticide Mixtures using Intelligent Biosensors

Pesticides are widely used in agricultural crops, forests and wetlands as insecticides, fungicides, herbicides and nematocides. Many of them are considered to be particularly hazardous compounds and toxic because they inhibit fundamental metabolic pathways. Due to their high acute toxicity and risk towards the population, some directives have been established to limit the presence of pesticides in water and food resources. Concerning the quality of water for human consumption, the European Council directive 98/83/CE (Drinking Water Directive) has set a maximum admissible concentration of 0.1 μg L-1 per pesticide and 0.5 μg L-1 for the total amount of pesticides. Organophosphates (OPs) are a class of synthetic pesticides developed from the Second World War, which are used as insecticides and nerve agents (Bajgar et al., 2004; Raushel, 2002). Since the removal of organochlorine insecticides from use, OPs have become the most widely used insecticides. They are normally used for agricultural, industrial, household and medical purposes. OPs poison insects and mammals by phosphorylation of the acetylcholinesterase (AChE) enzyme at nerve endings (Dubois, 1971; Ecobichon, 2001). Inactivation of this enzyme results in an accumulation of acetylcholine leading to an overstimulation of the effector organ (Aldridge, 1950; Reigart et al., 1999). The hazardous nature of OPs and their wide usage has led to concerted efforts for developing highly sensitive detection techniques as well as efficient destruction methods for these compounds (Gill et al., 2000). Detection techniques are fundamental in order to accurately determine the level of contamination of waters by pesticides. They are classically based on extraction, cleanup and analysis using gas chromatography (GC) or liquid chromatography (LC) coupled to sensitive and specific detectors (Ballesteros et al., 2004; Geerdink et al., 2002; Kuster et al., 2006; Lacorte et al., 1993). Although they are very sensitive, these techniques are expensive and time consuming (involve extensive preparation steps), they are not adapted for in situ and real time detection and often require highly trained personnel. In addition, these methods are not able to provide any information concerning the toxicity of the sample. AChE biosensors appear as a rapid and simple alternative method for the detection of OPs insecticides. A successful AChE biosensor for toxicity monitoring should offer comparable Source: Intelligent and Biosensors, Book edited by: Vernon S. Somerset, ISBN 978-953-7619-58-9, pp. 386, January 2010, INTECH, Croatia, downloaded from SCIYO.COM