电感耦合等离子体质谱法测定甜味剂中重金属元素

采用微波消解-八极杆碰撞/反应池(ORS)-电感耦合等离子体质谱仪(ICP-MS)测定甜味剂中Cr，Co，Ni，Cu，As，Cd，Sn，Sb，Hg，Pb等十种重金属元素的含量。样品用硝酸+双氧水消解后，试液直接用ICP-MS法进行测定。应用ORS技术，有效地消除了多原子离子对待测元素的干扰，选用45Sc，89Y，115In和209Bi等元素为内标混合液校正基体效应和信号漂移，确定了实验的最佳测定条件。结果表明，该方法对十种待测元素的检出限在0.003～0.038 μg·L-1之间，加标回收率在93.0%～106.6%之间，相对标准偏差(RSD)≤3.4%。方法简便、快速、准确，可以用于食品甜味剂质量控制和安全评价。

Direct Determination of Heavy Metal Elements in Sweeteners by Inductively Coupled Plasma Mass Spectrometry

An analysis method of microwave digestion and inductively coupled plasma-mass spectrometry (ICP-MS) with octopole reaction system (ORS) was established for the determination of 10 heavy metal elements including Cr, Co, Ni, Cu, As, Cd, Sn, Sb, Hg and Pb in sweetener. Samples were decomposed by HNO₃ and H₂O₂ followed by dilution with ultrapure water then the above 10 heavy metal elements in the solution were analyzed directly by ICP-MS. The use of ORS can eliminate the interference of polyatomic ions dramatically. 45Sc, 89Y, 115In and 209Bi as internal standard elements were used to compensate matrix effect and signal drift. The optimum conditions for the determination was tested and discussed. Under the optimal conditions, the detection limits of the 10 elements were in the range of 0.003～0.038 μg·L-1, the recovery of the samples was in the range of 93.0%～106.6% and the relative standard deviation(RSD)≤3.4%, which showed that the method was very precise. The technique was applied for the quality control and safety evaluation of sweetener.