Development and application of electrochemical sensor of boron-doped diamond (BDD) modified by drop casting with tin hexacyanoferrate

Abstract

This work presents the development and characterization of an electrochemical sensor of tin hexacyanoferrate (SnHCF), produced from the modification by drop casting of the boron-doped diamond electrode (BDD), and its subsequent evaluation in the determination of dopamine (DP) in a synthetic saliva sample. The sensors, BDD-SnHCF and unmodified BDD, were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy, where the BDD-SnHCF presented higher roughness and lower resistance to electronic transfer. Raman spectroscopy and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the chemical composition and bonding of the SnHCF film. The electroactive area and the heterogeneous electron transfer rate constant (k0) presented higher values for BDD-SnHCF. Analytical curves were constructed, by batch injection analysis (BIA) with amperometric detection (BIA-AMP), and the slope obtained for BDD-SnHCF was significantly higher when compared with unmodified BDD. The detection limit for BDD-SnHCF (0.21 μmol L−1) presented a value sevenfold lower than unmodified BDD and good analytical frequency (72 h−1) obtained for the modified electrode. The determination of DP in saliva, as a proof-of-concept, achieved an excellent accuracy, reported by a recovery of (90% ± 8) in the sample. The results showed that SnHCF is an interesting alternative for the BDD drop casting modification, presenting a significant improvement in the electrochemical characteristics and analytical performance of DP in the determination by BIA-AMP compared with unmodified BDD.