Synthesis and electrochemical properties of KPb4−xCax(PO4)3 (0 ≤ x ≤ 1.5) for oxidation of cadmium at graphite electrode

Chemically modified carbon paste electrode (CPE) for cadmium (II) analysis has been constructed by mixing KPb4−xCax(PO4)3 (0 ≤ x ≤ 1.5) (CaLA) and graphite powder. The lacunar apatite was synthesized using solid reaction and characterized by X-ray diffraction (XRD), infrared spectroscopy (IR) and Raman spectroscopy. The refinement study was carried out using Rietveld method where the obtained results show a good agreement between the observed and calculated patterns. The detection of cadmium (II) was investigated in acetate buffer (pH 4.5) using differential pulse anodic stripping voltammetry (DPASV). The limit of detection obtained under the optimized experimental conditions was 5.35 × 10−7 mol L−1 with a relative standard deviation of 2.37%. Possible interferences were tested and evaluated in 5.0 × 10−5 mol L−1 cadmium (II) in the presence of other inorganic ions. Finally, the proposed method was successfully applied to determine cadmium (II) in seawater and mussel samples. Hence, the satisfactory results confirm the applicability of this sensor in practical analysis.