Carbon paste Electrode Bulk-Modified with the Conducting Polymer Poly(1,8-Diaminonaphthalene):Application to Lead Determination

摘要

Carbon paste electrodes modified with conducting polymers for sensitive and selective determination of lead are presented.A novel method for generating a reproducible polymer-coated electrode surface is developed.We prove that 1,8-diamino-naphthalene (1,8-DAN) mixed with a carobon paste electrode leads to a conducting polymer in acidic medium while,in the same medium,this polymer is known to be non-conducting on platinum electrode.The electrode behaviour of poly(1,8-DAN),electropolymerised into carbon paste,was investigated by cyclic voltam-metry in the presence of the ferri-ferrocyanide couple.A carbon paste electrode modified with poly(1,8-DAN) was used to determine Pb~2+ in aqueous solutions.Pb~2+ ions were firstly complexes and then electrochemically deposited by a potential step to -0.9V.The accumulated lead after reduction was anodically stripped by differential pulse voltammetry.Different parameters,such as pH of the solution,preconcentration time,and electropolymerisation procedures were studied.For a preconcentration time of ten minutes,the calibration graph was linear from 40 to 2070 ng mL~-1 with r~2=0.998.The detection limit was found to be 30 ng mL~-1,and the relative standard deviation was 6%.