Ultra high performance liquid chromatography with tandem mass spectrometry method for determining dinotefuran and its main metabolites in samples of plants, animal-derived foods, soil, and water.

An ultra high-performance liquid chromatography with tandem triple quadrupole mass spectrometry residue method was developed and validated for the quantification and identification of dinotefuran and its main metabolites 1-methyl-3-(tetrahydro-3-furylmethyl) urea and 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine in fruit (watermelon), vegetable (cucumber), cereal (rice), animal-derived foods (milk, egg, and pork), soil, and water. The samples were extracted with acetonitrile containing 15% v/v acetic acid and purified with dispersive solid-phase extraction with octadecylsilane, primary secondary amine, graphitized carbon black, or zirconia-coated silica prior to analysis. The method had an excellent linearity (R2  ≥ 0.9942, 1-500 μg/L) and satisfactory recoveries (73-102%) at five spiked levels (0.001, 0.01, 0.05, 0.5, and 2 mg/kg) with intra- or interday precision in the range of 0.8-9.5% and 3.0-12.8% for the three compounds in the eight matrices. The limits of quantification were 10 μg/kg for 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine and 1 μg/kg for 1-methyl-3-(tetrahydro-3-furylmethyl) urea and dinotefuran. The applicability of the developed method was demonstrated by determining the occurrence of dinotefuran, 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine, and 1-methyl-3-(tetrahydro-3-furylmethyl) urea in various samples from plants, animal-derived foods, and the environment. From 80 samples, 70 contained dinotefuran (0.8-11.7 μg/kg), among which six also contained 1-methyl-3-(tetrahydro-3-furylmethyl) urea (water and rice, 0.5-0.9 μg/kg).