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VIII SIMPOSIO INTERNAZIONALE ICPBR HAZARDS
OF PESTICIDES TO BEES Effetti dell’imidacloprid sulle api Determination of Imidacloprid Residues by HPLC-MS/MS Ralf Schöning
and Richard Schmuck
The new analytical method allows the determination of the parent compound and two metabolites of the insecticide imidacloprid in rape and sunflower (pollen, flowers, leaves), plant nectar, honey, wax and bees. Residues of imidacloprid and its metabolites 5-OH-imidacloprid and olefin-imidacloprid are extracted with methanol/water. The extracts are subjected to clean-up on ChemElut and silica gel prior to quantification by reversed phase HPLC with electrospray MS/MS-detection. External bracketing standards in matrix are used to compensate possible matrix effects in the ion source. The overall recoveries for imidacloprid, 5-OH-imidacloprid and olefin-imidacloprid are between 91 and 97% with a relative standard deviation between 6.0 and 8.5% for all sample materials. The detector linearity and the repeatability of the method proved to be excellent. The limit of quantification for imidacloprid and 5-OH-imidacloprid is 0.005 mg/kg, and for the olefin-metabolite 0.01 mg/kg. Numerous field studies with different imidacloprid containing products were conducted to determine the residue levels of imidacloprid and relevant metabolites in seed-treated rape, and sunflower. Small bee colonies were caged in the flowering sunflower and rape plots as collecting devices for nectar and pollen. Samples of the flower petals, pollen, nectar, leaves and honey bees were analyzed by the new HPLC-MS/MS method. The analyses results showed no quantifiable residues in any sample material. Accordingly, a hazard
potential for honey bees from an imidacloprid seed treatment is not
indicated as there is no exposure to the compound.
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