ICP-MS法测定食品级二甲基硅油中的As、Cd、Hg、Pb毒理性元素

Determination of the Toxic Elements As, Cd, Hg and Pb in Food Grade Dimethicone by Inductively Coupled Plasma Mass Spectrometry

建立了直接稀释-电感耦合等离子体质谱（ICP-MS）法测定食品级二甲基硅油中As、Cd、Hg、Pb毒理性元素。样品用煤油稀释，使用ICP．MS法直接进样测定，通过在等离子体中引入氧气，避免样品溶液中高浓度碳冷凝沉积在质谱锥接口和离子透镜上导致分析元素灵敏度的降低的现象，应用碰撞／反应池校正多原子离子对As元素的质谱干扰，采用基体匹配方法消除基体干扰，在样品溶液和标准溶液中加入Au溶液校正Hg元素的记忆效应。As、Cd、Hg、Pb元素的检出限分别为0．58、0．16、0．87、0．12ng／L，线性相关系数均在0．9999以上，方法的回收率为93．25％～102．70％之间，相对标准偏差小于4．61％，实际样品分析均检出了4个毒理性元素，但含量极低，不会对人体构成危害。该方法简便、快速、准确，可以用来进行食品级二甲基硅油的质量控制和安全评价。

A method of inductively coupled plasma mass spectrometry （ICP-MS） was established to determine As, Cd, Hg and Pb toxic elements in dimethicone after diluted by kerosene. The condensation and deposition of high concentrations of carbon in mass cone interface and ion lens, which will decrease the sensitivity of element analysis, can be avoided effectively by introducing O2 to plasma. The mass spectral interferences of polyatomic ions to As element were corrected by collision reaction cell and the matrix matching method was used to eliminate matrix interference. On the other hand, the memory effect of Hg was corrected by the addition of Au in sample solution and standard solution. The detection limit of As, Cd, Hg and Pb was 0.58, 0.16, 0.87, 0.12 ng/L, respectively, with a correlation coefficient higher than 0.9999. The recovery rate was 93.25%-102.70%, with a relative standard deviation less than 4.61%. These four toxic elements were all detected in practical analysis, and their content was very low, which had no harm to human body. The method can be applied for the quality control and safety evaluation of food grade dimethicone.