ABSTRACT
Recent research performed in our laboratory (using a butyrylcholinesterase+choline oxidase enzyme electrode) suggested the validity of the biosensor approach using enzyme inhibition OPEEs (i.e. enzyme electrodes working in organic phase) in the case of organophosphorus and carbamate pesticides, which are poorly soluble in aqueous solutions. Since these pesticides are generally much more soluble in chloroform than in water, the present research aimed at analysing this class of pesticides using a tyrosinase inhibition OPEE operating in water-saturated chloroform medium. The tyrosinase biosensor was assembled using an oxygen amperometric transducer coupled to the tyrosinase enzyme, immobilized in kappa-carrageenan gel. Lastly a detailed comparison between the inhibition monoenzymatic tyrosinase and inhibition bienzymatic (butyrylcholinesterase+choline oxidase) OPEEs was performed and discussed in this work.
Subject(s)
Biosensing Techniques , Carbamates/pharmacology , Chemistry Techniques, Analytical/methods , Monophenol Monooxygenase/chemistry , Organophosphorus Compounds/pharmacology , Pesticides/pharmacology , Alcohol Oxidoreductases/chemistry , Alcohol Oxidoreductases/pharmacology , Butyrylcholinesterase/chemistry , Butyrylcholinesterase/pharmacology , Calibration , Carrageenan/chemistry , Electrochemistry/methods , Enzymes, Immobilized/chemistry , Gels , Models, Chemical , Monophenol Monooxygenase/antagonists & inhibitors , Pesticides/chemistryABSTRACT
Several triazine pesticides, such as atrazine, are much more soluble in several organic solvents, such as chloroform, than in water. Our recent research was aimed at analyzing this class of pesticides using tyrosinase OPEE (organic phase enzyme electrodes), exploiting their inhibiting action on the tyrosinase enzyme when operating in water-saturated chloroform medium. In this work we studied the response of a tyrosinase inhibition enzyme sensor to several triazinic (simazine, propazine, terbuthylazine) and benzotriazinic (azinphos-ethyl and azinphos-methyl) pesticides (LOD=0.5x10(-9) mol l(-1)). Recovery trials were also performed in vegetal matrixes (corn, barley, lentils). Lastly, the effect of the solvent (chloroform or water) on the inhibition process was investigated via Hill's equation and the diffusion of analyte from the solvent to the enzyme membrane.