Electroanalytical performances of electrodes modified with porous layers of carbon nanotubes or ion-exchange polymers

In the last years, electroanalysis has witnessed a great growth in the employment of carbon nanotubes (CNTs) layers and/or in the use of polymer films to develop “chemically modified electrodes” [1-2]. The final devices present better electroanalytical performances, particularly in terms of peak current increase and of voltammetric peak separation narrowing, useful features for increasing selectivity and sensitivity and for lowering detection limits. The better performances are not only to be searched in a change of electrode kinetics (e.g. catalytic effects brought by nanomaterials or their functionalization, decrease in charge transfer resistance) or in an increment of surface area or porosity distribution, but also in an analyte adsorptive preconcentration capability and in a change of the mass transport regime, from planar to convergent or to thin-layer [3-4]. In this presentation, we would like to contribute to this debated topic, with some experimental results obtained working with different modified electrodes: 1) electrodes modified with appropriately functionalized CNTs; 2) electrodes modified with Sulphonated Poly (Aryl Ether Sulphones), a new class of polymers, ad hoc tailored for electroanalytical applications; 3) electrodes modified with polyamidoamines and cyclodextrins; 4) electrodes modified with electrospun polymers. The above mentioned modifications have led to a general increase in the analyte adsorption capabilities and in the film mesoporosity which, also according to theoretical studies [4], is the responsible of the transition from the linear diffusion regime to the thin-layer behavior. Both phenomena cause the enhancement of the peak currents, improving sensor performances. Optimization of the sensor devices for the detection of some contaminants of emerging concern (e.g. benzidines, o-toluidine, tolidine, halothane) and their application in real-world analytical cases are also presented and discussed. ACKNOWLEDGEMENTS This work has been supported by Fondazione Cariplo (Milano, Italy), grant no. 2014-1285. REFERENCES [1] M. Pumera The Chemical Record, 2012, 12, 201-213. [2] C. Gouveia-Caridade, C.M.A. Brett Current Analytical Chem., 2008, 4, 206-214. [3] I. Streeter, R. Baron and R.G. Compton J. Phys. Chem. C, 2007, 111, 17008–17014. [4] M.C. Henstridge, E. J. F. Dickinson, M. Aslanoglu, C. Batchelor-McAuley and R.G. Compton Sensors Actuators B Chem., 2010, 145, 417–427.