高效液相色谱-串联质谱法测定食品中的尿素、缩二脲与双氰胺

建立了高效液相色谱-串联质谱法同时检测食品中尿素、缩二脲和双氰胺的方法。样品经水浸泡并混匀，加入乙腈沉淀蛋白，通过冷冻离心去除脂肪，取清液挥干后用1.0 mL 70%乙腈水溶液复溶、过膜。采用电喷雾负离子电离（ESI+）模式和多反应监控（MRM）扫描模式，外标法定量。该方法在0.1~20.0 mg/L范围内线性关系良好，相关系数（r2）大于0.995。尿素、缩二脲和双氰胺的检出限分别为0.03、0.05、0.01 mg/L，定量下限分别为0.08、0.10、0.03 mg/L。加标水平为5.0、10.0、20.0 mg/kg时，尿素、缩二脲和双氰胺的平均回收率为70%~99%，相对标准偏差为0.42%~8.0%。该方法简便、灵敏、精确，适用于食品中尿素、缩二脲和双氰胺的检测。

Determination of Urea,Biruet and Dicyandiamide in Foods by High Performance Liquid Chromatography-Tandem Mass Spectrometry

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.