Carbon Nanotubes/PAMAM Platform for Easily Ascorbic Acid Determination

In the present work, a new composite based on carbon nanotubes and the PAMAM G1 dendrimer was synthesized. The material was then reacted with zinc and potassium hexacyanoferrate to form a mixed- valence complex material NTCDZnH. This material was characterized by spectroscopic and analytical techniques such as Fourier transform infrared (FTIR), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), and Cyclic Voltammetry (CV). The cyclic voltammogram of the graphite paste electrode containing NTCDZnH material showed two redox couples with a formal potential Eθ’ of 0.097 V and 0.88 V (II) attributed to the redox processes FeII / FeIII and FeII(CN)6 /FeIII(CN)6 in the presence of Zn2+, respectively (20% w/w; v = 20 mV s−1; NaNO3 1.0 mol L−1). After optimizing the main analytical and instrumental parameters (electrolyte support, concentration, pH, and scanning rate), the graphite paste electrode containing the material was tested in the electrocatalytic determination of ascorbic acid. The analytical curve exhibited excellent linearity over a concentration range of 1.0 × 10−5 mol L−1 to 8.0 × 10−4 mol L−1. The best limit of detection was 8.68 × 10−6 mol L−1 with a relative standard deviation of 4.96% (n = 3) and amperometric sensitivity of 1.19 × 102 mA/mol L−1, allowing the successful analysis of ascorbic acid in pharmaceutical formulations.