[Determination of seven organophosphorus insecticides in fruits and vegetables by ultra-high performance liquid chromatography-tandem mass spectrometry based on magnetic conjugated microporous polymers].

A method was developed for the determination of seven organophosphorus insecticides in fruits and vegetables by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) based on magnetic conjugated microporous polymers (CMPs). Fe3O4 nanoparticles modified by phenylene and ethynylene were cross-linked with 1,3,5-tribromobenzene and 1,3,5-trialkynylbenzene to obtain magnetic CMPs. This material with a three-dimensional network structure and covalently built-in Fe3O4 nanoparticles could effectively enrich organophosphorus insecticides with a conjugated structure, thus allowing for convenient magnetic separation in an external magnetic field. Under the optimized conditions, the seven organophosphorus pesticides were extracted by using the magnetic CMPs as magnetic solid phase extraction adsorbents. The limits of detection (LODs) of the seven target analytes were in the range of 0.12-5.0 ng/kg. The recoveries were between 80.8% and 125%, and the relative standard deviations (RSDs, n=5) were less than 6%. The organophosphorus insecticides were detected in fruits and vegetables at concentrations in the range of 1.1-500.0 ng/kg. The method is sensitive, accurate and reliable, and it shows good application potential for the determination of the organophosphorus pesticides in fruits and vegetables.