Determination of lead(II) by online novel electrolyte dropping electrode using 1,10-phenanthroline in flow injection system

The transfer of Pb(II) facilitated by 1,10-phenanthroline (phen) presented in the methyl isobutyl ketone (MIBK) across the polarized water|MIBK interface was systematically investigated by novel electrolyte dropping electrode using cyclic voltammetry and square wave voltammetry. The protonation of 1,10-phenanthroline in polarized water|MIBK interface was explored. The dependence of the half-wave potential on PbCl2 and phen concentration was investigated and the stoichiometry of resulting metal ligand complex was formulated. Different concentrations of PbCl2 was determined online and the transfer peak current was proportional to the bulk concentration of the Pb2+ varied between 8 μM to 0.5 mM and 0.5 to 1 mM, and the linear regression coefficients were 0.9953 and 0.9995, respectively. The standard deviations (RSD) were 4.33, 5.80, 4.13, 3.88, 2.23, 3.39, 1.38, 2.42, 2.00, 2.73 and 2.37% for 8 times successive determinations of Pb2+ for the concentrations of 0.008, 0.05, 0.1, 0.2, 0.3, 0.35, 0.4, 0.5, 0.8, 0.9 and 1 mM, respectively. The long time stability of the electrolyte dropping electrode was tested and the result showed that this novel method was simple, rapid and efficient.