Carbon Quantum Dots/Metal-Organic Framework Material Modified Electrode for Electrochemical Detection of Bisphenol A

CDs modified by PDDA with particle size of about 3 nm were prepared, and then loaded on Ce-MOFs with firewood like nanorod structure by electrostatic adsorption, to prepared the composite material (PDDA-CDs/Ce-MOFs). The modified electrode prepared by dropping the composite material on the surface of GCE was used for the enrichment of BPA in milk, with enrichment voltage of 0.3 V and enrichment time of 150 s, and the concentration of BPA enriched on modified electrode was determined by differential pulse voltammetry. Results showed that the oxidation response current of BPA on the modified electrode was about 25 times than that of GCE, and the oxidation process was a process controlled by adsorption with two electrons and two protons to participate in the tranfer; linearity relationship between the concentration of BPA and its respective oxidation peak current was kept in the ranges of 0.01-5.0 μmol·L^-1 and 5.0-50 μmol·L^-1, with detection limit (3S/N) of 2.2 nmol·L^-1. 5.0 μmol·L^-1 BPA standard solution was determined for 6 times in parallel, giving RSDs (n=6) of 4.6%. After the modified electrode was storaged for 7 d and 28 d, the oxidation peak current of BPA decreased to 96.8% and 95.4% of the initial current, respectively. It was found that the modified electrode has good repeatability and stability. The proposed method was used for the determination of 6 milk samples, and no BPA was detected. A spiked recovery test was made on 6 samples, giving recoveries of BPA in the range of 97.4%-105%, and RSDs (n=5) of the determined values were found in the range of 2.1%-4.2%.