Determination of disulfoton and its metabolites in agricultural products by dispersive soild phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

Disulfoton, an organophosphorus pesticide, is used to control cotton, beet, potato, and other seedling period aphids, leaf moths, underground pests, etc., with internal absorption, killing, gastric poisoning, and fumigation. Disulfoton is a highly toxic organophosphate pesticide, which can inhibit cholinesterase activity, resulting in neurophysiological disorders by inhalation, feeding, and transdermal absorption. Disulfoton is difficult to degrade in the environment, which leads to enrichment in organisms and interference with endocrine. This compound is harmful to the ecological environment and human health. To ensure the quality and safety of food, it is important to develop a detection method for disulfoton and its metabolites in agricultural products. A reliable method based on dispersive solid phase extraction (d-SPE) with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for the determination of disulfoton and its metabolites (disulfoton sulfone, disulfoton sulfoxide, demeton- , demeton- sulfone, and demeton- sulfoxide) in agricultural products (pea, asparagus, wheat, coffee bean, and peanut). The optimal extraction method was as follows: 5.0 g the samples were extracted with acetonitrile (wheat, coffee bean, and peanut presoaked in 5 mL water) in a 50 mL centrifuge tube, followed by 10 min vortex. Before 30 s vortex, 4 g NaCl was added. After 5 min centrifugation, 1.5 mL of the supernatant was cleaned up with 50 mg octadecylsilane bonded silica (C ), 50 mg primary secondary amine (PSA), and 50 mg aminopropyl (NH ) adsorbents. The analytes were separated on a Thermo Syncronis C column (150 mm×2.1 mm, 5 μm) with gradient elution using water and acetonitrile at a column temperature of 40 ℃. The injection volume was 2 μL. Disulfoton and its metabolites were analyzed in multiple reaction monitoring (MRM) mode with positive electrospray ionization (ESI ) for the selective quantification. Qualitative and quantitative analyses were accorded to the retention times and characteristic ion pairs with one parent ion and two fragment ions. Quantitative analysis was performed by an external standard method using matrix-matched calibration curves. All the parameters that affected the extraction efficiencies were optimized. C , PSA, and NH gave good recoveries of 87.9%-109.0%. Other adsorbents, multiwalled carbon nanotubes (MWCNTs), hydroxylated multiwalled carbon nanotubes (OH-MWCNTs), carboxylated multiwalled carbon