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Abstract
Electrochemical sensors were prepared from conducting polymer; poly (3,4- ethylenedioxythiophene) (PEDOT) and the inclusion of different mediators namely; ferrocene carboxylic acid (FC1), ferrocene (FC2) and cobaltocene (CC). The mediators were applied to the surface using two approaches: (i) FC or CC have been 2sandwiched3 between two layers of PEDOT in presence of sodium dodecyl sulfate (PEDOT/mediator/PEDOT SDS) and (ii) FC or CC sandwiched between two layers of PEDOT and gold nanoparticles (PEDOT/mediator/Aunano). The performance of the mediator in these different composites was evaluated for the electrocatalytic oxidation of some organic compounds namely; dopamine (DA), morphine (MO) and tramadol (Tr). The results showed that FC1 exhibited higher mediation for electron transfer and enhanced electrocatalytic activity in both approaches due to the inclusion of the ferrocenium ion and the polar substituted {u2013}COOH group in the conducting polymer matrix which increases the electronic conduction of the film. SDS showed a great effect for enhancing the preconcentration/accumulation of the studied compounds at the surface which leads to faster electron transfer. Different parameters relevant to sensors were considered such as the reproducibility, sensitivity, selectivity, stability of the redox signals, as well as detection limits