Simultaneous electrochemical determination of cadmium(II), lead(II), and mercury(II) ions in water and food samples using N1-hydroxy-N1,N2-diphenylbenzamidine and multi-walled carbon nanotubes modified carbon paste electrode

A novel modified carbon paste electrode has been developed using a laboratory synthesized metal chelating ligand (L), N1-hydroxy-N-1,N-2-diphenylbenzamidine (HDPBA) and multi-walled carbon nanotubes (MWCNTs) composite (L-MWCNTs/CPE). The developed modified electrode was applied for selective and sensitive simultaneous electrochemical determination of cadmium(II), lead(II), and mercury(II) using square wave anodic stripping voltammetry (SWASV). The accumulation of metal ions on the electrode surface was performed in 0.1 M acetate buffer solution (ABS, pH 5.0) by applying a potential of -1.10 V versus Ag/AgCl for 210 s, followed by stripping in the positive potential scan of the SWASV after a rest time of 10 s. Under the optimum experimental conditions, the linear dynamic ranges were found to be 2x10(-4)-2, 1x10(-4)-2 and 2x10(-3)-2 mu M of cadmium(II), lead(II), and mercury(II), respectively, with the detection limits (LODs) of 2.5x10(-2), 7.8x10(-3) and 4.6x10(-1) nM for cadmium(II), lead(II), and mercury(II), respectively. The proposed electrode exhibited high sensitivity for the determination of these metal ions with excellent reproducibility and stability. The influence of several ions on the simultaneous determination of Cd(II), Pb(II), and Hg(II) was studied, and the prepared electrode was found to be highly selective for the detection of the three metal ions. The developed electrode was effectively applied to the determination of the three metal ions in water, vegetable and tobacco samples, and the obtained results were similar to those measured with graphite furnace atomic absorption spectrometry (GFAAS).