Determination of Nanomolar Concentrations of Pb(II) Using Carbon Paste Electrode Modified with Zirconium Phosphated Amorphous Silica

Abstract

Abstract A sensitive and selective method for the determination of Pb(II) with a zirconium phosphated silica gel (SiZrPH) modified carbon paste electrode has been developed. The measurements were carried out in three steps including an open circuit accumulation following by electrolysis of accumulated Pb(II) at the modified carbon paste electrode and differential pulse voltammetric determination. The analytical performance was evaluated with respect to the carbon paste composition, pH of solution at the accumulation step, pH and concentration of supporting electrolyte, electrolysis potential, accumulation time and electrolysis time. Two linear calibration graphs were obtained in the concentration ranges 2.5×10 −9 mol L −1 –5.0×10 −8 mol L −1 and 5.0×10 −8 mol L −1 –5.0×10 −6 mol L −1 with an accumulation time of 120 s. The detection limit was found to be 3.5×10 −10 mol L −1 . The effects of potential interfering ions were studied, and it was found that the proposed procedure is free from interferences of common interfering ions such as tin, thallium and etc. The developed method was applied to Pb(II) determination in a wastewater sample.