Determination of Trace Amount of Cadmium(II) in Environmental Samples by Functionalized Graphene Oxide Modified Carbon Paste Electrode

In this study graphene oxide was functionalized by 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) and incorporated into a carbon paste electrode. This modified electrode was applied for determination of trace amount of cadmium (II). The analysis procedure is consist of three steps, firstly, an open circuit accumulation in stirred sample solution was occurred for 7 min. Cd2+ was accumulated on the surface of a modified Carbon paste electrode via forming Cd-5-Br-PADAP complex. This step was followed by medium exchange to a 0.1 mol L-1 HCl solution, where the accumulated cadmium was reduced for 15 s at -1.10 V (vs. Ag/AgCl). Finally, cadmium was oxidized, and voltammograms were recorded by scanning the potential in a positive direction. The calibration plot was linear over the cadmium concentration range from 0.25-210 pg L-1. The detection limit was 9.7 × 10-2 pg L-1. Using this new modified carbon paste electrode, trace level of Cd2+ in water samples was determined.