Bimetallic UiO-66(Zr/Ce) MOF encapsulated reduced graphene oxide nanocomposite for voltametric detection of trace Lomefloxacin residues in milk

The abuse and persistent use of Lomefloxacin (LOM) produces residues that deteriorate the ecological environment and endanger human health. Therefore, it is highly urgent to establish a simple and reliable method for the determination of LOM to guarantee food safety. Herein, a sensitive voltametric sensor based on bimetallic UiO-66(Zr/Ce) MOF/reduced graphene oxide (UiO-66 (Zr/Ce)/rGO) was fabricated for the determination of trace LOM residues in milk. The UiO-66(Zr/Ce)/rGO increased the electroactive surface area and lowered the charge transfer resistance. Due to the synergistic interactions between UiO-66(Zr/Ce) MOFs with good electrocatalytic activity and rGO nanosheets with high electrical conductivity, the UiO-66(Zr/Ce)/rGO/GCE exhibited the highest peak current response of LOM, 4.2-fold higher than the bare GCE. Consequently, the UiO-66(Zr/Ce)/rGO showed remarkably electrocatalytic activity for LOM oxidation with two broad linear detection ranges (0.03 – 2.0 μM and 2.0 – 30 μM), high sensitivities (5.1254 and 0.2198 μM μA −1 ), and a low detection limit (5.0 nM). The UiO-66(Zr/Ce)/rGO exhibited strong anti-interfering ability against potential interfering species even at high concentration, and maintained robust voltametric responses up to 25 days. Moreover, the UiO-66(Zr/Ce)/rGO/GCE achieved accurate determination of trace LOM residues in liquid milk with good recovery (96.11 − 103.2 %) and highly consistent sensitivity with that in PBS.