蓖麻油中无机元素的质谱分析

建立了乙醇稀释-电感耦合等离子体质谱(ICP-MS)法测定蓖麻油中多个无机微量元素的分析方法。蓖麻油样品用乙醇稀释，使用ICP-MS法直接测定。在等离子体氩气流中加入少量氧气，使高浓度有机溶液进入等离子体中完全燃烧，防止了高碳在质谱锥口和离子透镜上的冷凝沉积，采用八极杆碰撞/反应池(ORS)消除了质谱干扰，多元素(Sc，Ge，Rh，Ir)内标溶液的使用消除了基体效应，维持了各元素分析信号的稳定，通过向待测溶液中加入Au标准溶液，使元素Hg形成金汞齐消除了记忆效应。20个待测元素的线性相关系数≥0.999 5，检出限在0.06～20.1 ng·L-1之间，回收率为90.4%～110.2%，相对标准偏差(RSD)≤4.8%。通过对不同来源蓖麻油样品进行分析，结果显示，三个样品中元素的含量存在较大差异。方法能快速、简便、准确测定蓖麻油中的多个无机元素。

Analysis of Trace Inorganic Elements in Castor Oil by Inductively Coupled Plasma Mass Spectrometry

A method for the determination of Na, Mg, Si, P, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Hg and Pb in castor oil after direct dilution with ethanol by inductively coupled plasma mass spectrometry (ICP-MS) was established. The sample was diluted by ethanol before ICP-MS determination. The condensation and deposition of high concentrations of carbon in mass cone interface and ion lens, which will decrease the sensitivity of element analysis, were avoided effectively by introducing O₂ to plasma. The mass spectral interferences were eliminated by octopole reaction system (ORS). The matrix effects were calibrated to using Sc, Ge, Rh and Ir as internal standard elements. Au standard solution, which could form amalgam alloy with Hg, was dropped to eliminate the memory effect of Hg. The results show that the correlation coefficient for analyte is no less than 0.999 5, the detection limits is in the range of 0.06～20.1 ng·L-1, the recovery is in the range of 990.4%～110.2%, and the RSD is less than 4.8%. This method was very fast, simple and accurate to simultaneously analyze multi-elements in castor oil.