Surface modification prepared porous copper oxide/(Cu-S) metal-organic framework/reduced graphene oxide hierarchical structure for highly selective electrochemical quercetin detection.

Electrochemical alkalization of (Cu-S) metal-organic framework (MOF) and graphene oxide ((Cu-S) MOF/GO) composite yields a new CuO/(Cu-S) MOF/RGO (reduced GO) composite with porous morphology on screen printed carbon electrode (SPCE) which facilitated the electron transfer properties in electrochemical quercetin (QUE) detection. A selective QUE detection ability has been demonstrated by the constructed electrochemical sensor (CuO/(Cu-S) MOF/RGO/SPCE), which also has a broad dynamic range of 0.5 to 115 µM in pH 3 by differential pulse voltammetry. The detection limit is 0.083 µM (S/N = 3). In this study, it was  observed that the real samples contained 0.34 mg mL and 27.7 µg g QUE in wine and onion, respectively.