Surface functionalization of natural hydroxyapatite by polymerization of β-cyclodextrin: Application as electrode material for the electrochemical detection of Pb(II)

A composite material prepared by polymerization of β-cyclodextrin (β-CD) on the surface of natural hydroxyapatite using citric acid as cross linker, was employed as electrode material for the detection of Pb(II). Hydroxyapatite was obtained from bovine bones, following a three-step procedure including pre-calcination, chemical treatment with (NH4)2HPO4 and calcination. The structure of the pristine hydroxyapatite (NHAPP0.5) and its functionalized counterpart (NHAPp0.5-CA-β-CD) materials was examined using XRD and FTIR. Upon deposition as thin film on a glassy carbon electrode (GCE), the ion exchange ability of NHAPp0.5-CA-β-CD was exploited to elaborate a sensitive sensor for the detection of lead. The electroanalytical procedure was based on the chemical accumulation of lead ions under open-circuit conditions, followed by the detection of the preconcentrated species using differential pulse anodic stripping voltammetry. The reproducibility of the proposed method based on different measurements in a solution containing 2 µM lead gave a coefficient of variation of 1.27%. Significant parameters that can affect the lead stripping response were optimized: a linear calibration curve for lead (II) in the concentration range of 2 × 10− 8 mol L− 1 − 20 × 10− 8 mol L− 1 (R2 = 0.998) was obtained. The detection limit (DL = 3S/M) and the sensitivity of the proposed sensor were 5.06 × 10− 10 mol L− 1 and 100.80 µA.µM− 1, respectively. The interfering effect of several ions expected to affect the stripping determination of lead was evaluated, and the proposed sensor was also successfully applied in the determination of Pb2+ ions in spring water and well water.