Preconcentration effect of ion-exchange polymers in lead electroanalyticical determination

In the last couple of decades, electrode coatings based on proton conducting polymers were extensively adopted in the electroanalytical field for the preparation of modified electrodes to be used as more performing sensors. In fact, these devices offer several advantages: they reduce adsorption phenomena, suppress the inclusion of interfering species, protect the electroactive surface from passivation and fouling, act as pre-concentrating agents towards selected analytes, modify the process kinetics and diffusion yielding to high sensitivity and selectivity [1-3]. In this context, in this presentation, we would like to show some results on the use of sulphonated poly(aryl ether sulphone) (SPAES), an innovative polymer in this field, whose properties can be appropriately designed, tailored and used in the preparation of modified electrodes for electroanalytical applications. Since connectivity and morphology of the modifier polymer are critical factors in controlling conductivity, stability, active surface and diffusion mechanism of the modified electrode, much attention is devoted to the polymer casting conditions and procedure on the glassy carbon support. In particular, the effect of the use of different casting solvents [dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), N-methylpyrrolidone (NMP)], characterized by different properties, is evaluated. On the other hand, polymers prepared with different IEC (Ion exchange Capabilities) are also tested. A Principal Component chemometric Analysis is also employed for the results rationalization. Finally, the performances of the different membranes are evaluated in the electroanalytical determination of lead, focusing on the analyte adsorptive preconcentration capability of the casted polymers. For this purpose, linear sweep voltammetry with and without the stripping preconcentration step is employed and the best conditions for the lead determination are discussed.