| A high performance liquid chromatography-tandem mass spectrometryic（HPLC-MS/MS） method was established for the simultaneous determination of urea,biruet and dicyandiamide in foods.Samples were soaked and mixed in water,then removed proteins by adding acetonitrile and frozen centrifuged to remove fat.The clear liquid was evaporated to dryness,and the residue was dissolved in 1 mL 70% ACN solution,and filtrated with membrane.The analytes were identified by HPLC-MS/MS with the positive electrospray ionization（ESI+） under multiple reaction monitoring（MRM） mode,and analyzed quantitatively by the external standard method.The calibration curves were linear in the concentration range of 0.1-20.0 mg/L for three compounds with correlation coefficients（r2） more than 0.995.The limits of detection（LODs） of urea,biruet and dicyandiamide were 0.03,0.05,0.01 mg/L,respectively,and their limits of quantitation（LOQs） were 0.08,0.10,0.03 mg/L,respectively.The average recoveries for urea,biruet and dicyandiamide at spiked concentration levels of 5.0,10.0,20.0 mg/kg were in the range of 70%-99% with relative standard derivations（RSDs） of 0.42%-8.0%.The method was simple,sensitive and accurate,and was suitable for the determination of urea,biruet and dicyandiamide residue in food samples. |