奶粉中二噁英前处理方法的探讨

[目的]建立快速溶剂萃取(ASE)的前处理方法,并改进纯化步骤。采用该前处理方法将国际二噁英标准参考物质进行验证。[方法]采用ASE法和索氏提取2种提取方法对奶粉样品进行充分萃取,再选用FMS专用净化装置对样品进行纯化,采用同位素稀释,以各化合物的同位素标记物为回收率内标,以13C-1,2,3,4-TCDD和13C-1,2,3,7,8,9,-HxCDD为定量内标。用高分辨气相色谱(HRGC)和高分辨双聚焦质谱(HRMS)联用技术进行定性和定量分析。[结果]ASE和索氏提取前处理所得的同位素标记化合物平均回收率分别为66.9%和66.5%,测定实际样品的相对标准偏差分别为18.4%和12.3%。[结论]通过比较ASE与索氏提取2种方法,ASE前处理便捷、时间短、所需溶剂少,回收率和精密度都符合美国EPA1613中的要求,通过用该法测定,结果也接近了欧盟2002/69/EC的规定,即每次测定的同位素标记物回收率不少于60%,如单个化合物的TEQ量小于10%总量TEQ时,不受上述限制。

A discussion on pretreatment method of dioxins in milk powder

[Objective] To establish a pretreatment method to accelerate solvent extraction(ASE) and improve clean-up process and.apply this method to certify the standard reference materials of dioxins [Methods] After being extracted by SOXHLET and ASE,then being cleaned up by FMS,samples of milk powder were diluted by isotope and analyzed by the HRGC/HRMS technique quantitatively and qualitatively. [Results] The recovery rate of isotopic labeled standard compounds by SOXHLET and ASE were 66.9% and 66.5% respectively,and the comparative standard variation of RSD were 18.4% and 12.3%. [Conclusion] As a newly developed pretreatment method to accelerate solvent extraction and clean-up technique,ASE is convenient,quick and solvent-saving.Its recovery rate and density meet coith the regulation of USEPA method 1613 and are close to the regulation of EU 2002/69/EC that isotopic labeled material is recovered not less than 60%.If TEQ in single compound is less than 10% of total TEQ,it is no longer under the above restriction.