New Immunosensors Operating in Organic Phase (OPIEs) for Analysis of Triazinic Pesticides in Olive Oil

Several tests were carried out on the possibility of fabricating immunosensors working in organic solvents or solvent mixtures and aimed at developing new immunosensors for the analysis of triazinic pesticides present in hydrophobic matrices such as olive oil. Initially, an immunosensor for atrazine was tested in which a hydrogen peroxide electrode was used as transducer and peroxidase enzyme as marker. The competitive process took place in a chloroform–hexane 50 % (V/V) mixture, while the subsequent enzymatic measurement was performed in an aqueous buffer solution. A linear response of between about 50 nM and 5.0 µM was obtained versus atrazine in presence of oil. Subsequently, attempts were also made using a Clark electrode as transducer and performing not only the competition but also the final enzymatic measure in organic solvent. The latter enzymatic measurement was thus carried out in several different organic solvents, such as decane, hexane, chloroform and chloroformhexane mixture. The best analytical results were obtained using decane as solvent and tert‐butylhydroperoxide as substrate of the enzymatic reaction.