Nickel hexacyanoferrate supported at nickel nanoparticles for voltammetric determination of rifampicin

Abstract

A rapid and simple method for voltammetric determination of rifampicin (RIF) using a glassy carbon electrode (GCE) modified with nanostructured nickel hexacyanoferrate (NiHCF) was developed. The sensor was prepared through an unusual method to NiHCF electrosynthesis, starting from nickel nanoparticles previously deposited on the surface of different electrodes (glassy carbon, ITO and gold electrode) under potentiodynamic conditions. X ray diffractograms of Ni nanoparticles thin film were obtained for different stages of NiHCF films formation indicating a homogeneous distribution throughout the substrate with a mean size around 40 nm and an irregular shape. EQCM studies showed that the nature of cations can promote strong alterations on the voltammetric and microgravimetric profile during the growth of NiHCF due to the ion transport mechanisms of redox reactions. Both voltammetric and microgravimetric behavior were studied in the presence of sodium, lithium and potassium ions and the best responses were found using potassium ions as supporting electrolyte. The presence of RIF promoted a decrease in the cathodic peak current of NiHCF, suggesting an interaction between the antibiotic and Ni species presented at the electrode surface. The variation in the current signal was proportional to the RIF concentration and it was adopted for its quantification, allowing the construction of a linear analytical curve from 5.0 × 10−6 to 5.0 × 10−4 mol L−1 with a limit of detection of 2.6 μmol L−1. The method was successfully applied for RIF determination in simulated human urine samples with good agreement between the added and recovery values.