Anchoring Au on UiO-66 surface with thioglycolic acid for simultaneous SERS detection of paraquat and diquat residues in cabbage

SERS sensors based on metal-organic frameworks (MOFs) have garnered considerable attention in trace pesticide residue detection. UiO-66/AuNPs suspension substrates were fabricated by introducing thioglycolic acid (TGA) as a binder to modify the surface of AuNPs to facilitate their electrostatic assembly with UiO-66 prepared through hydrothermal reaction. The proposed substrates were used for quantitative and simultaneous analysis of paraquat and diquat in cabbage. Diquat and paraquat in actual cabbage samples were individually analysed with detection of limits (LOD) of 6 μg/L and 3 μg/L, respectively, and validated with recoveries ranging from 92.65 to 118.34%. Furthermore, the UiO-66/AuNPs substrate was able to differentiate between paraquat and diquat mixtures, even for the concentrations in the cabbage extracts differed by a factor of 100. The proposed UiO-66/AuNPs substrate provides a potentially useful tool for the trace determination of pesticide residues in the practical food safety analysis