液相色谱-串联质谱同位素稀释法测定奶粉中双氰胺的残留

Isotope dilution determination of dicyandiamide in milk powder by liquid chromatography-tandem mass spectrometry

中文关键词:  双氰胺  奶粉  高压液相色谱-串联质谱法  同位素稀释法

英文关键词:dicyandiamide  milk product  LC-MS  isotope dilution

中文摘要:

      目的 建立并优化高压液相色谱-串联质谱法快速检测奶粉中双氰胺残留的方法。方法 奶粉样品经1%三氯乙酸溶液沉淀蛋白后, 通过Sep-pak AC-2离子交换固相萃取柱净化样品提取液, 去除奶粉中其他复杂基质的干扰, 浓缩后用初始流动相复溶、过膜。采用电喷雾正离子电离(ESI+)模式和多反应监测(MRM)扫描模式, 通过Acquity BEH Amide(3.0 mm×150 mm, 1.7 μm)色谱柱分离检测双氰胺目标化合物, 同位素15N4-双氰胺稀释法定量。结果 该方法在50~1200 μg/kg范围内线性良好, 相关系数r>0.998, 在三种不同基质样品中的最低检测限与最低定量限分别为2.5 μg/kg和8 μg/kg, 加标回收率为93.4%~112.3%, 相对标准偏差均<10.3%。结论 该方法简便、灵敏、精确, 不仅筛选优化了液相、质谱条件参数, 同时优化了奶粉样品的前处理方法, 适用于奶粉中双氰胺残留的检测。

英文摘要:

      Objective To establish a rapid analytical method to determine the residues of dicyandiamide in milk powder. Methods After precipitating proteins of the milk powder sample by 1% trichloroacetic acid solution, the sample extract was purified by Sep-pak AC-2 ion exchange solid phase extraction column, which could remove the interference of complex matrix in the milk powder. Then it was concentrated and reconstituted by the initial mobile phase, and went through the film. The dicyandiamide target compounds were separated by Acquity BEH Amide (3.0 mm×150 mm, 1.7 μm) column and were detected by liquid chromatography-tandem mass spectrometry (LC-MS) with electrospray ionization (ESI) in multiple reaction monitoring method (MRM). Accurate determination was achieved by using isotope 15N4-dicyandiamide as internal standard. Results The method showed a good linearity over the range of 50~1200 μg/kg with r>0.998 and the lowest detection limit and the lower limit of quantification in three different matrix samples were 2.5 μg/kg and 8 μg/kg. The mean recoveries ranged from 93.4% to 112.3%. The relative standard deviation was less than 10.3%. Conclusion This method is simple, sensitive and accurate, and can not only optimize the parameters of the liquid phase and the conditions of mass spectrometry, but also optimize the pre-treatment methods of the milk powder sample. It can be applied to detect the residues of dicyandiamide in milk powder.