Determination of copper(II) in the dairy product by an electrochemical sensor based on click chemistry

Herein, a novel sensitive electrochemical sensor for copper(II) based on Cu(I) catalyzed alkyne–azide cycloaddition reaction (CuAAC) is described. The catalyst of Cu(I) species is derived from electrochemical reduction of Cu(II) through bulk electrolysis (BE) with coulometry technique. The propargyl-functionalized ferrocene (propargyl-functionalized Fc) is covalently coupled onto the electrode surface via CuAAC reaction and forms propargyl-functionalized Fc modified gold electrode, which allows a good and stable electrochemical signal. The change of current at peak (dI), detected by differential pulse voltammetry (DPV), exhibits a linear response to the logarithm of Cu(II) concentration in the range of 1.0 × 10−14–1.0 × 10−9 mol L−1. It is also found that the proposed sensor has a good selectivity for copper(II) assay even in the presence of other common metal ions. Additionally, the proposed method has been applied to determine copper(II) in the dairy product (yoghurt) with satisfactory results.

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► Propargyl-functionalized Fc can be covalently coupled on the electrode surface via CuAAC reaction.
► Catalyst of Cu(I) is derived from the electrochemical reduction of Cu(II) via bulk electrolysis.
► propargyl-functionalized Fc modified electrode allows a good and stable electrochemical signal.
► The proposed sensor has high sensitivity and good selectivity for detection of Cu(II).