Determination of heavy metals by a mercury-plated diamondlike carbon microelectrode array

Abstract

Mercury-plated as well as bare nitrogenated diamond-like carbon (NDLC) microelectrode arrays have been investigated for application in in-situ determination of heavy metals (Cu, Pb and Cd) by differential pulse anodic stripping voltammetry (DPASV). A microelectrode array consisting of 50 625 microdiscs with 3 μm in diameter and interelectrode distances of 20 μm was fabricated on a highly conductive silicon substrate and characterized by CV measurements. Current responses of all metals were linear for metal concentrations in the range of 1.6 × 10-8 to 8.3 × 10-8 mol/L and preconcentration time 5 min. The stripping current responses of the bare microelectrode array reached under the same conditions were much lower in comparison with a mercury-plated array. A strong effect upon stripping current responses of metals was observed of adding a small amount of thiocyanate (2 × 10-3 mol/L) into the plating solution. © 2007 IOP Publishing Ltd.