同位素稀释质谱法用于CCQM-K21(鱼油中p,p′-DDT)关键比对测量

Isotope Dilution Mass Spectrometry Applied for the Key Cmmparison of CCQM-K21(Determination of p,p′-DDT in Fish Oil)

应用先进的GPC前处理技术去除鱼油中 99%的油脂基体 ,浓硫酸破坏残余油脂 ,利用GC -MS -SIM选择测量样品中p ,p′ -DDT及加入的13 C12 -p ,p′ -DDT的碎片离子峰面积比值 ,通过括号法计算得到样品中p ,p′ -DDT的准确含量 ,测量结果的不确定度小于 0 .6 %。在各国报出的测量结果中 ,我们的测量结果最准确 ,不确定度最小。

Weigh fish oil 2 g and add 13 C 12- p,p′-DDT sith almost the same amount as the p,p′-DDT in the weighed fish oil.Mix and add octane till the total volume is 10 mL.Applied the technique of GPC for removing 99% of lipids in fish oil.The GPC system is consisted of a glass preparation column(350 mm×20 mm)with filled material(Bio-beads S-X3,200-400 mesh),a HPLC pump and an UV detector.CH 2Cl 2:hexane=1∶1 as eluent and flow rate is 4 mL/min.Per-injection of the sample into GPC system is 1ml.Detection wavelength is 210 nm.The collected solution from Gpc is blown to dry by N 2.2 mL hexane washes the residue and 0.5 mL of concentrated sulfuric acid destroys the remained lipids.GC-MS-SIM measured the ratio of p,p′-DDT(m/z 234.99)and 13 C 12 -p,p′-DDT(m/z 246.99). A HP SE-30MS capillary column is used.Bracketing is used as quantitative method.Uncertainties of measurement results are not more than 0.6%.Our results are the best ones with the smallest uncertainties in the nine mational laboratories.