Use of boron-doped diamond electrode pre-treated cathodically for the determination of trace metals in honey by differential pulse voltammetry

In this work, a methodology for the determination of Cu(II), Pb(II), Cd(II) and Zn(II) in honey by differential pulse anodic stripping voltammetry (DPASV) on a nano crystalline boron-doped diamond electrode (BDD) is proposed. A 33 Box-Behnken Design, 32 Factorial Design and Principal Components Analysis (PCA) were performed to optimise the electrochemical conditions. According to the response surfaces obtained, it was stipulated for Zn analysis a pH of 4, Ed of −1.50 V and td of 240 s. For simultaneous analysis of Cu, Pb and Cd a pH of 1, Ed of −0.95 V and td of 240 s was used. Detection limits of 0.37, 0.40, 1.28 and 0.16 μg L−1 were found for Cu, Pb, Cd and Zn, respectively. The analyte concentration ranged between 0.242 and 1.38 mg L−1 for Cu, 0.129 and 0.918 mg L−1 for Pb and 0.819 and 2.492 mg L−1 for Zn, while no significant concentrations were found during Cd analyses. The honey samples were also analysed by Hg-coated glassy carbon electrode and graphite furnace atomic absorption spectrometry (GF AAS) through non-parametric ANOVA and no evidence of significant differences among the results was observed within a 95% confidence interval.