Adsorptive Stripping Differential Pulse Voltammetric Determination of Risperidone with a Multi-Walled Carbon Nanotube-Ionic Liquid Paste Modified Glassy Carbon Electrode

A new composite electrode has been fabricated based on coating multi-walled carbon nanotubes (MWCNTs) and n-octylpyridinum hexafluorophosphate (OPPF6) ionic liquid composite on a glassy carbon (GC) electrode (OPPF6-MWCNTs/GCE). This electrode shows very attractive electrochemical performances for electrooxidation of risperidone (RIS) compared to conventional electrodes using carbon and mineral oil, notably improved sensitivity and stability. The oxidation peak potentials in cyclic voltammogram of RIS on the OPPF6-MWCNTs/GCE was occurred around 230 mV vs. SCE at Britton-Robinson (B-R) buffer (pH 4.0) at scan rate of 100 mV s(-1). The electrochemical parameters such as diffusion coefficient (D), charge transfer coefficient (alpha) and the electron transfer rate constant (k(s)) were determined using cyclic voltammetry. Under the optimized conditions, the peak current was linear to risperidone concentration over the concentration range of 10-200 nM with sensitivity of 0.016 mu A/nM(-1) using differential pulse voltammetry. The detection limit was 6.54 nM (S/N = 3). The electrode also displayed good selectivity and repeatability. In the presence of clozapine (CLZ) the response of RIS kept almost unchanged. Thus this electrode could find application in the determination of RIS in some real samples. The analytical performance of the OPPF6-MWCNTs/GCE was demonstrated for the determination of RIS in human serum and pharmaceutical samples.