Copper-based metal organic framework modified electrochemical sensor for detection of quercetin in food samples

Abstract

In this study, a new sensor was fabricated for the detection of quercetin where carbon paste electrode (CPE) modified with a copper-based metal-organic framework (Cu-MOF) was utilized as transducer. The Cu-MOF was successfully synthesized using a hydrothermal method. After characterization of the MOF structure, CPE was modified with Cu-MOF via drop-casting method (Cu-MOF/CPE). It was observed that Cu-MOF/CPE displayed a remarkable effect on the electrochemical quercetin signals by increasing the oxidation signal of quercetin about three times compared to the bare electrode. After optimizing the experimental conditions via differential pulse voltammetry, the oxidation mechanism of quercetin was explored using cyclic voltammetry. As a result, it was discovered that the redox process of quercetin on Cu-MOF/CPE was controlled by adsorption. On the other hand, the analytical characteristics of developed sensor were also examined. Consequently, the prepared sensor possessed two linear ranges of 0.01 - 1 mu M and 1-70 mu M of quercetin. Meanwhile, the limit of detection values was found 0.008 mu M and 0.043 mu M, respectively, while the limit of quantification values was 0.026 mu M and 0.142 mu M, respectively. The relative standard deviation value for the detection of 50 mu M quercetin in the standard solution was 0.874% (n = 3). Additionally, the proposed sensor presented satisfactory reproducibility and selectivity for the determination of quercetin in apple and grape juice.