Preparation of magnetic metal organic framework: A magnetically induced improvement effect for detection of parathion-methyl

Abstract Parathion-methyl (PTM) as one of organophosphate insecticides was once widely used to control pests on rice, cotton and other crops. Recently, due to high toxicity to people, PTM has been prohibited in vegetable and fruit production process but illegal abuse of PTM occasionally happens in some areas. Conventional detection methods for PTM suffer from cumbersome sample pretreatment or insufficient sensitivity. In this work, we rationally prepare metal organic framework MIL-101 decorated with Au nanoparticles and cysteine modified Fe3O4 (designated as /Cys-Fe3O4/MIL-101) as magnetic surface enhanced Raman scattering (SERS) substrate. Benefiting the magnetically induced improvement effect, by using Au/Cys-Fe3O4/MIL-101, the SERS method exhibits superior sensitivity and detection reproducibility, which is successfully used to detect PTM residue in juice. The limit of detection for PTM at 5 ppb in juice is reached with a good linearity ranging from 10−11 to 10-7 M, meeting the requirement of the European Union Standard.