DPV Determination of Pb in Fine Particles PM_2.5 with Poly(3-Hexylthiophene)-Graphene-Nafion Modified GCE as Working Electrode

A portion of suspension of poly(3-hexylthiophene)-graphene (P3HT-Gr) in DMF (1 g·L^-1, 10 μL) was coated onto the glassy carbon electrode (GCE), which, after drying at room temperature, was further coated upon its surface by dropping with a definite amount of 0.5% (w) Nafion ethanol solution, thus to prepare the P3HT-Gr-Narion modified GCE. The electrochemical behavior of Pb(Ⅱ)-ion at this modified electrode was studied by CV and DPV. It was found that an apparent oxidation peak was observed at -0.713 V, with its peak current 6 times higher than that with the bare GCE. In an acetate buffer solution of pH 5.0, and under the conditions of 1 deposition potential of -1.0 V, 2 deposition time of 150 s and 3 scanning rate of 100 mV·s^-1, linear relationship between values of oxidation peak current and concentration of Pb²⁺-ion was obtained in the range of 0.010 to 4.5 μmol·L^-1, with detection limit (3S/N) of 5.0×10^-9mol·L^-1. It was shown that good selectivity was obtained in the determination of lead. The results of Pb(Ⅱ) determined in the PM_2.5 samples by the proposed method were found in consistency with those found by spectrophotometry.