The Direct Voltammetric Determination Of Heavy Metals In Complex Samples By Chemically Modified Electrodes

Chemically modified electrode, especially self-assembled monolayer modified electrode, became one of the important research fields in electroanalytical chemistry because of its remarkable merit and extensive application purpose. However, the dominating problem of electrochemical methods applied in application was the contamination on the surfaces of sensitive electrodes. Self-assembled monolayer modified electrode with special functional groups can effectively protect the surface of the electrode, and be used to the rapid and handy determination of metals in samples, which has applied value and good future. The creative works are summarized three aspects as follows:1. A novel method for the direct determination of copper in complex samples on MAA modified gold electrode combining underpotential deposition with subtractive square wave anodic stripping voltammetry was proposed. A disorganized porous monolayer was formed on the surface of MAA modified gold electrode, which permits the penetration of copper ions and inhibits the pass of large molecular. Hence a good selectivity was obtained on the MAA modified electrode. The concentration of copper in solution containing human serum albumin could be direct detected on the modified electrode and a linear range of 8×l0-7~l×10-5 mol/L proportional to currents of stripping peaks was obtained. The concentration of copper in complex environmental samples was direct determined on the MAA modified electrode and a satisfying result was obtained.2. Kinetic process of copper binding to human serum albumin (HSA) was first studied on the MES modified gold electrode with stripping voltammetry. The concentrations of free copper ions containing HSA could be detected on the MES modified electrode until the equilibrium of the binding was reached. A two-step consecutive model was firstly derived to describe the binding process. The kinetic parameters of copper binding to HSA were obtained by the non-linear fitting.3. A novel method for the direct determination of copper containing surfactant on a heteroaromatic compound MBI modified gold electrode was proposed. MBI monolayer was characterized by the electrochemical methods. The behavior of stripping voltammetry on the MBI modified electrode was investigated and the mechanism was preliminary elucidated. The concentration of copper down to 10ppb could be detected by the MBI modified electrode combining a preconcentration step with differential pulse stripping voltammetry. The direct determination of copper in the presence of surfactant was achieved on the modified electrode. Hence MBI modified gold electrode possible be used to the direct determination of copper in complex samples.