Carbon-based modified electrodes for o-toluidine voltammetric detection

Different modified electrodes, based on the screen-printing technology (SPE) or prepared by the casting procedure using different carbon materials (carbon nanotubes, graphene, graphite,...) have been prepared and fully characterized by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Also the effect of the use of different supporting materials was studied. The final devices have been compared with GC electrode, for the development of a new electroanalytical methodology for the detection of o-toluidine, an organic carcinogenic synthetic pollutant mainly used as an intermediate in production of azo-dyes, already studied by the research group in a previous work [1]. The developed method is based on voltammetric techniques, which allow to achieve excellent results in terms of large dynamic concentration ranges, high accuracy and precision and low limits of detection and quantification [2]. The use of nanomaterials (in particular carbon nanotubes) enhances the potentialities of the method, improving sensitivity and lowering detection limits [3]. In particular, o-toluidine was detected using Linear Sweep Voltammetry in the range 1.5-7 ppm, obtaining a limit of detection of 0.16 ppm and excellent apparent recovery factors (102%) and repeatability, in comparison with carbon based-screen printed electrodes, which presented problems of fouling, probably due to polymerization products. This new method was used for the determination of o-toluidine during its photodegradation mediated by ZnO photocatalyst, showing better performances than C-SPE and comparable with HPLC. Moreover, the methodology was also employed to monitor o-toluidine absorption by cyclodextrine nanosponges based on hydrogel polyamidoamines (PAA), allowing to discriminate among various types of resins and to obtain absorption kinetic parameters.[1] L. Falciola, V. Pifferi, E. Mascheroni, Electroanalysis , 24, (2012), 767. [2] C.M.A. Brett, A.M. Oliveira-Brett, J. Solid State Electrochemistry, 15, (2011), 1487. [3] J.J. Gooding, Electrochimica Acta, 50, (2005), 3049.