Agent orange herbicides, organophosphate and triazinic pesticides analysis in olive oil and industrial oil mill waste effluents using new organic phase immunosensors

New immunosensors working in organic solvent mixtures (OPIEs) for the analysis of traces of different pesticides (triazinic, organophosphates and chlorurates) present in hydrophobic matrices such as olive oil were developed and tested. A Clark 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 final measurement was performed in decane and using tert-butylhydroperoxide as substrate of the enzymatic reaction. A linear response of between about 10 nM and 5.0 μM was usually obtained in the presence of olive oil. Recovery tests were carried out in commercial or artisanal extra virgin olive oil. Traces of pesticides were also checked in the oily matrix, in pomace and mill wastewaters from an industrial oil mill. Immunosensors show good selectivity and satisfactory precision and recovery tests performed in olive oil gave excellent results.