Effect of the sp2/sp3 Ratio in a Hybrid Nanocarbon Thin Film Electrode for Anodic Stripping Voltammetry Fabricated by Unbalanced Magnetron Sputtering Equipment

摘要

The effect of the sp2/sp3 ratio in an unbalanced magnetron sputtered nanocarbon film electrode was studied for determining Cd2+ and Pb2+ by anodic stripping voltammetry (ASV). The signal-to-noise ratio in the ASV measurement improved as the sp3 concentration in the carbon film increased because the noise current decreased with the increasing sp3 concentration. The detection limits with a carbon film containing 50% sp3 were 0.25 and 1.0 μg L−1 for Cd2+ and Pb2+ with high repeatability (Cd: 4.6% and Pb: 6.4%, n = 3). For a real sample measurement, a pretreatment system combining a photooxidation reactor and a cation exchange column was used to eliminate the interference from EDTA and Cu2+, which forms a stable complex or alloy with Cd2+ and Pb2+. More than 99% of the interference was eliminated, and accurate signal currents for Cd2+ and Pb2+ were successfully obtained with the pretreatment system.