Curcumin-based ratiometric electrochemical sensing interface for the detection of Cd²⁺ and Pb²⁺ in grain products

The conventional electrochemical detection in food samples often suffers from low stability and poor reproducibility. The construction of ratiometric sensor is regarded as an effective means to overcome the issues. Herein, poly-curcumin (p-CCM)-Multi walled carbon nanotubes (MWCNTs)-layered double hydroxides (LDHs) was constructed as a novel rationmetric sensing material for detection of Cd2+ and Pb2+ in grain samples. Under the synergistic effect of MWCNTs and the adsorption capacity of LDHs, the p-CCM/MWCNTs/LDHs can significantly enhance the electrochemical responses of heavy metals. In the differential pulse voltammetry test, the ratio of oxidation peak currents between heavy metal ions and curcumin was directly proportional to the concentration of heavy metal ions. This has formed the basis of a new ratiometric electrochemical sensor for the detection of the levels of Cd2+ and Pb2+ in grain products. Under optimal conditions, the limits of detection for Cd2+ and Pb2+ were found to be 0.61 mu g mL(-1) and 0.74 mu g mL(-1), respectively. It is worth mentioning that the method was additionally utilized to detect Cd2+ and Pb2+ in rice and flour samples. The satisfactory recovery outcomes in both samples demonstrated minimal interference of the food matrix with the obtained ratiometric sensor. In this work, a CCM-based ratiometric electrochemical sensor was presented, which could potentially replace the widely used ferrocene-based ratiometric electrochemical sensor, thereby enhancing the exploration of electrode materials for ratiometric electrochemical sensors.