Rod-like hydroxyapatite and Nafion nanocomposite as an electrochemical matrix for simultaneous and sensitive detection of Hg2 +, Cu2 +, Pb2 + and Cd2 +

The uniform rod-like hydroxyapatite (HAP) particles were synthesized through a simple wet method, which was characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and transmission electron microscopy (TEM). The composite of HAP-Nafion was then prepared and used as a matrix for simultaneous determination of Hg2 +, Cu2 +, Pb2 + and Cd2 + by differential pulse anodic stripping voltammetry (DPASV). The good dispersibility, large specific surface area, rich active sites, and strong adsorption property of the composite contributed to the enhanced stripping signals of the four heavy metal ions. Under the optimized experimental conditions, the calibration curves for Hg2 + covered two linear ranges from 0.1 to 1.0 μM and from 3.0 to 10.0 μM. For Cu2 +, Pb2 + and Cd2 +, the linear calibration curves ranged from 0.1 μM to 10.0 μM. Based on a signal-to-noise ratio characteristic of 3, the detection limits of Hg2 +, Cu2 +, Pb2 + and Cd2 + were estimated to be 0.030 μM, 0.021 μM, 0.049 μM and 0.035 μM, respectively. The developed method was also utilized for the detection of Hg2 +, Cu2 +, Pb2 + and Cd2 + in real water samples, and satisfactory results were obtained.