Nanocompósito formado por nanotubos de carbono e por polietilenoimina como sensor eletroquímico para cloridrato de prometazina

Abstract

A sensor based on polyethylenimine-functionalized multi-walled carbon nanotubes/glassy carbon electrode (fMWCNT-PEI/GCE) was developed for promethazine hydrochloride (PMZ) detection in pharmaceutical samples. PMZ is oxidized at the modified electrode at more negative potentials and with higher sensitivity than at the bare electrode. The morphological characterization of the sensor surface showed a homogeneous layer with size distribution of the diameters of the composite ranging from 22–47 nm. The characterization of the electrochemical behavior suggested that an equal number of electrons and protons participate in the PMZ irreversible oxidation on the fMWCNT-PEI/GCE. The optimized conditions were Sörensen buffer at pH 2.0, frequency of the amplitude of the potential pulses of 90 s−1 , amplitude of the potential pulses of 40 mV, and height of the potential step of 2 mV. Based on the most sensitive peak, at 0.75 V, which is related to the formation of the phenazothiazonium ion, the PMZ calibration curve was obtained with detection limit of 2.31×10−7 mol L −1 , a linearity range of 8.91×10−7 to 5.03×10−6 mol L−1 . This methodology was successfully validated in pharmaceutical samples by comparison with the standard method of the British Pharmacopoeia, where a recovery of 109.54 % was obtained for the methodology developed in this work and 99.88 % for the standard method, showing high potential applicability of the fMWCNT-PEI/GCE.