Simultaneous electrochemical determination of heavy metals using a triphenylphosphine/MWCNTs composite carbon ionic liquid electrode

A constructed triphenylphosphine-modified carbon nanotube composite with a room temperature ionic liquid as pasting binder was employed as a novel electrode for sensitive and simultaneous determination of Cd2+, Pb2+ and Hg2+. The morphology and properties of electrodes surface were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. The electrochemical response characteristics of the modified electrode toward the analytes ions were investigated by square-wave anodic stripping voltammetry (SWASV). The responses of modified electrode for Cd2+, Pb2+ and Hg2+ were found to be improved significantly in comparison with those obtained using a conventional carbon paste electrode. The experimental conditions for simultaneous determination of these ions have been established. Relative standard deviations to detect the Cd2+, Pb2+ and Hg2+ in ternary mixtures were less than 3.0% and they can be determined in the ranges of 0.1–150.0 nM. Under optimal conditions the limits of detection were 6.0 × 10−5, 9.2 × 10−5 and 7.4 × 10−5 μM for Pb2+, Hg2+ and Cd2+ with a 75 s preconcentration, respectively. The method was applied to determine the cadmium, lead and mercury in soil, gasoline, fish, tap water and waste water samples.