Catalytic effect of potassium in Na1−xKxCdPb3(PO4)3 to detect mercury (II) in fish and seawater using a carbon paste electrode

• The anion-deficient apatite Na1−xKxCdPb3(PO4)3 was prepared using solid reaction.
• The catalytical effect of potassium was used to detect Hg (II) at carbon electrode.
• The effect of the chemical and electrochemical experimental variables was studied.
• The modified electrode was investigated to detect Hg (II) in fish and seawater.

In this paper, we report a synthesis of a new lacunar apatite, KCdPb3(PO4)3, using solid state method, and its application as modifier of carbon paste electrode (KLA-CPE) to determine mercury (II). Sodium replacement with potassium induced a linear variation of the crystallographic parameters a and c according to Vegard's law and led to amplify the electrical signal of the working electrode. The peak currents of mercury (II) increased linearly with their concentration at the range from 2.0×10−7 mol L−1 to 1.0×10−4 mol L−1 using differential pulse anodic stripping voltammetry. The detection limit was found to be 1.11×10−8 mol L−1. The use of this electrochemical sensor has been successfully implemented for the determination of Hg (II) in seawater and fish samples. The obtained results were found to be very satisfactory.

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