Imidacloprid d4

HPLC grade methanol, acetonitrile, and water were purchased from Fisher Scientific (Pittsburg, PA). Formic acid, acetamiprid, N-desmethyl-acetamiprid, thiacloprid, and thiacloprid-d₄ were purchased from Fluka (Seelze, Germany). 4-Methylumbelliferone-¹³C₄ was purchased from Cambridge Isotope Laboratories, Inc. (Andover, MA). Phosphoric acid, β-glucuronidase (E. coli), imidacloprid, Clothianidin-d₃, imidacloprid-d₄, and 4-methylumbelliferyl-β-D-glucuronide hydrate were purchased from Sigma-Aldrich (St. Louis, MO). ECBA, DCBA, and acetamiprid-d₅ were purchased from Cerilliant (Round Rock, TX). ECBA-d₅, DCBA-d₁₀, and N-desmethyl-acetamiprid-(²H, ¹³C, ¹⁵N₂) were purchased from CanSyn Chemical Corporation (Toronto, Canada). Potassium phosphate dibasic trihydrate was purchased from MP Biomedicals (Santa Ana, CA). Clothianidin was purchased from Chemservice (West Chester, PA). 5-Hydro-imidacloprid-d₄ was purchased from ClearSynth (Mississauga, ON, Canada). 5-Hydroxy-imidacloprid was a gift from Dr. Heiko Käfferlein of the Institute for Prevention and Occupational Medicine of the German Social Accident Insurance (Institute of the Ruhr-University, Bochum, Germany). Reagents, solvents, and standard materials were used without additional purification. The chemical structures of the target analytes are shown in Fig. 1.