Anodic stripping voltammetric determination of lead in tap water at an ordered mesoporous carbon/Nafion composite film electrode

A sensitive mercury-free lead (Pb2+) sensor has been proposed based on an ordered mesoporous carbon and Nafion composite film (OMC/Nafion) coated glassy carbon electrode. The analysis of Ph2+ using anodic stripping voltammetry (ASV) includes two steps. Pb2+ ions are firstly reduced and deposited on the electrode surface in a Ph2+ solution (10 mL) during a preconcentration step biased at -1.0 V, followed by a measurement step by differential pulse voltammetry (DPV) within the potential range of -0.8 to -0.3 V (scan rate: 20 mV/s, frequency: 20 Hz, amplitude: 50 mV, pulse width: 50 ms). Linear calibration curve was found to be from 20 nM to 2 mu M for Pb2+ with a sensitivity of 17.4 +/- 1.38 mu A/mu M after a 5-min of preconcentration. The detection limit was estimated to be around 4.60 +/- 0.12 nM at the signal to noise ratio of 3. Reproducibility (RSD%) was found to be 3.0% for a single sensor with eight measurements and 4.3% for five sensors prepared with identical procedures. The practical application of the proposed lead sensor was verified by determination of trace level of Pb2+ in tap water sample.