Mono-Enzyme Biosensor for the Detection of Organophosphorous Compounds

Organophosphorous compounds are important neuroactive molecules whose presents significant analytical challenges. New monoenzyme biosensor introduced here, is used for the measurement of the level of two organophosphorous compounds, paraoxon (POX) and ethyl parathion (EPA), in phosphate buffer. Prussian blue electrodepositionized on a graphite electrode served as a template for immobilization of monoenzyme layer. A monoenzyme layer containing choline oxidase was immobilized along with nafion and bovine serum albumin, by cross-linking with glutaraldehyde. The results revealed that the response of the proposed biosensor was linear between 5 μM and 80 μM in the presence of POX and EPA. Detection limits were 0.4 μM in both cases. Also, for the optimization of the biosensor performance, temperature and pH dependency, concentration of choline chloride as substrate of choline oxidase and incubation time were determined. The results showed that the optimum values for temperature, pH, substrate concentration and incubation time were room temperature, pH 7, 4 mM and 30 min, respectively.