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建立了磷酸铵沉淀-电感耦合等离子体质谱法测定菜籽油中微量S的检测方法。采用微波消解处理样品,选择48SO+作为观察信号,在动态反应池(DRC)内,O2作为反应气,与试样中的S元素生成48SO+,消除15N17O+,16O16O+等物质带来的质谱干扰;针对四级杆无法去除的48Ca+干扰(丰度:0.187%),通过加入磷酸铵生成沉淀去除,优化了沉淀所需磷酸铵用量及pH大小。方法的检出限为0.4 mg/kg,对精炼菜籽油和初榨菜籽油进行不同水平的添加,回收率为82.4%~112%,精密度为1.6%~3.9%(n=7)。方法可用于菜籽油中S元素的测定。
A method for determination of trace S in rapeseed oil by ammonium phosphate precipitation-inductively coupled plasma mass spectrometry was established. In the dynamic reaction cell (DRC), O2 was used as a reactive gas to generate 48SO + with S elements in the sample to eliminate the mass spectral interference caused by 15N17O +, 16O16O + and other substances. The 48Ca + interference (Abundance: 0.187%), which can not be removed by the rod, is removed by the addition of ammonium phosphate to optimize the amount of ammonium phosphate and the pH required for the precipitation. The detection limit of this method was 0.4 mg / kg. The recovery rates of refined rapeseed oil and primary rapeseed oil were 82.4% -112% and the precision was 1.6% -3.9% (n = 7) . The method can be used for the determination of S element in rapeseed oil.