Simultaneous Determination of Neonicotinoid Insecticides and Two Metabolites in Royal-jelly by LC-MS/MS

Pymetrozine, dinotefuran, nitenpyram, thiamethoxam, flonicamid and its metabolite (4-trifluoromethylnicotinamide), imidacloprid, clothianidin, imidaclothiz, acetamiprid and its metabolite (N-desmethylacetamiprid)) and thiacloprid residues in royal-jelly were detected by QuEChERS-LC-MS/MS. The royal-jelly samples were diluted by water, the protein of royal-jelly was precipitated by methanol and then the methanol supernatant solution was cleaned up with PSA, C18 and MgSO₄ by QuEChERS method, the supernatant solution was evaporated to dryness and reconstituted in methanol-0.15% formic acid solution (1∶9, V/V), and then filtered through nylon membrane into a glass LC vial for LC-MS/MS analysis. The solution was separated by Agilent Eclipse XDB-C18 column (150 mm×4.6 mm×5 μm) and the quantitative detection was performed on LC-MS/MS by multiple reaction monitoring (MRM) mode under positive electrospray ionization mode (ESI⁺). Isotopes internal standard method (dinotefuran, thiamethoxam, imidacloprid, clothianidin, acetamiprid and thiacloprid) and external standard method (pymetrozine, nitenpyram, flonicamid, 4-trifluoromethylnicotinamide, imidaclothiz and N-desmethylacetamiprid) were used for quantitation analysis. The limits of quantification (LOQs, S/N=10) of pymetrozine, dinotefuran are 2.5 μg/kg, nitenpyram, imidaclothiz, acetamiprid, thiacloprid are 5.0 μg/kg, thiamethoxam, flonicamid, imidacloprid, clothianidin, 4-trifluoromethylnicotinamide, N-desmethylacetamiprid are 12.5 μg/kg, respectively. The correlation coefficients are more than 0.996, the recoveries and the relative standard deviations (RSD) are 81.2%-119% and 1.7%-12.2%, respectively. This method is convenient, rapid and effective, QuEChERS(quick, easy, cheap, effective and rugged) is suitable for determination and confirmation of pymetrozine, dinotefuran, nitenpyram, thiamethoxam, flonicamid and its metabolite (4-trifluoromethylnicotinamide), imidacloprid, clothianidin, imidaclothiz, thiacloprid, acetamiprid and its metabolite (N-desmethylacetamiprid).