Mercaptobenzothiazole-on-Gold Organic Phase Biosensor Systems: 3. Thick-Film Biosensors for Organophosphate and Carbamate Pesticide Determination

Abstract

The last few decades has seen an increase in the use of pesticides in order to increase crop yields. This has resulted in the increased use of organophosphorous (OP) and carbamate (CM) pesticide compounds since they result in much lower bioaccumulation and higher biodegradability, therefore they have replaced organochlorine as the most popular pesticides. However, as with the overuse of many pesticides, the OP and CM compounds leave residues in the soil, crops and surface water, which in turn exert a great threat to the environment and human health. The OP and CM compounds enter organisms and then inhibit the activity of acetyl cholinesterase (AChE) by irreversibly binding to the active site of this enzyme, which is important for the transmission of nerve impulses (Wu et al., 2009; Somerset et al., 2009; Garcia de Llasera et al., 2009; Mavrikou et al., 2008; Liu et al., 2008; Boon et al., 2008; Pinheiro & De Andrade, 2009). A broad range of adverse effects can result from AChE inhibition and it includes abdominal pain and cramps, glandular secretions, skeletal muscle twitching, flaccid paralysis, tiredness, nausea, blurred vision, drowsiness, eye pain, convulsions, respiratory failure and untimely death. Furthermore, OP and CM compounds are now also known to have mutagenic, carcinogenic and teratogenic effects and have been included in the list of known endocrine disruptor compounds (Luo & Zhang, 2009; Wu et al., 2009; Liu et al., 2008; Fu et al., 2009; Caetano & Machado, 2008). Due to the increasing toxicity and adverse effects of pesticides, many countries are now monitoring environmental and food samples for pesticides and have established maximum residue levels (MRLs) for various pesticides in food products (Hildebrandt et al., 2008). Some of the conventional methods used for chemical analysis of pesticides include spectrophotometry, infrared spectrometry, flow-injection chemiluminescence, fluorimetry, fluorescence spectrometry, mass spectrometry, but mainly chromatographic techniques, such as gas chromatography-mass spectrometry (GC–MS) and high-performance liquid