Determination Of Trace Heavy Metals With Polymer Film Modified Electrode By Electrochemical Polymerization

Poly(N,N-dimethylaniline) is a polyanline derivative, which has some special chemical properties for the side-chain with a strong ecectron-donating group -N(CH3)2. Different from the radical cation formed on polystyrene, it can easily substituted on the nitrogen atom to form stable delocalized radical cation without dopping, and can interact with amine nucleophiles under certain conditions. The poly(N,N-dimethylaniline) polymer film by electrochemical polymerization contains lots of positive charge, and it can used for the determination of anion in solution by electrostatic adsorption. This paper introduced the preparation and application of poly(N,N-dimethylaniline) modified electrode according to the latest literature, at the presence of iodine ions in water samples, the modified electrode can adsorbed the lead, cadmium and copper indirectly, based on the adsorption of the modified electrode, new methods for the separate determination of Pb²⁺,Cd²⁺,Cu²⁺ in water sample were established.In this paper, poly(N,N-dimethylaniline) modified glassy carbon electrode was prepared by cyclic votammetry, the parameters of electropolymerization were discussed; Pb²⁺,Cd²⁺,Cu²⁺ formed a complex with iodide anions and accumulated on the modified electrode, then a new method for the determination of lead, cadmium and copper was established. Under the best accumulation and determination solution, different parameters such as the pH of the accumulating solution, preconcentration time, the scan potential, scan rate and so on were optimized. The interference of other ions were also studied.The conclusions of the experiment were as follows: at the optimum experiment condition, when scanned by linear sweep voltammetry, a well-defined oxidation peak of lead was at -0.54V, the linear range was 5×10^-7mol/L⁵×10-5mol/L with a detection limit of 5×10-5mol/L; when anodically stripped by differential pulse voltammetry, the well-defined anodic peak of cadmium was at -0.9V, the linear range was 0.01¹mg/L with a detection limit of 0.006mg/L; when anodically stripped by differential pulse voltammetry, the well-defined anodic peak of copper was at -0.48V, the linear range was 0.05²mg/L with a detection limit of 0.01mg/L.This modified electrode is easy prepared and reuseable, the method for the determination of heavy metal ions is simple, reproducible. The determination results of lead,cadmium and copper in waste water is good, it can be regarded as an new alternative to the conventional method, the future high performance of this electrode as potential detecting electrodes and scensors are foresee.