Key Laboratory of Biogeology and Environmental Geology of Ministry of Education, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, PR China.
Talanta. 2011 May 15;84(3):887-94. doi: 10.1016/j.talanta.2011.02.026. Epub 2011 Feb 23.
Direct determination of trace arsenic in high chlorine food samples by ICP-MS is complicated by the presence of ArCl(+) interferences, and the high first ionization energy of As (9.81 eV) also results in low analytical sensitivity in ICP-MS. In this work, two strategies based on ion-molecule reactions were successfully used to eliminate ArCl spectral interference in a dynamic reaction cell (DRC). The interference ion ((40)Ar(35)Cl(+)) was directly removed by the reaction with methane gas, and the background signal was reduced by up to 100-fold at m/z 75. Alternatively, by using molecule oxygen as the reaction gas, (75)As(+) was effectively converted to (75)As(16)O(+) that could be detected at m/z 91 where the background is low. The poor signal intensity of As or AsO was improved 3-4 times by addition of 4% methanol in the analyzed solutions. The limit of quantitation (LOQ) for (75)As (CH(4)-DRC method) and (75)As(16)O (O(2)-DRC method) was 0.8 and 0.3 ng g(-1) and the analytical results of seaweed and yellow croaker standard reference materials were in good agreement with the certified values. As the routine arsenic monitoring method in our laboratory, it was applied to the accuracy determination of 119 high chlorine food samples from eight different markets of Beijing.
电感耦合等离子体质谱法（ICP-MS）直接测定高氯食品样品中的痕量砷时，会受到 ArCl(+) 干扰的影响，而 As 的第一电离能较高（9.81 eV），也导致在 ICP-MS 中分析灵敏度较低。在这项工作中，成功地使用了两种基于离子-分子反应的策略，在动态反应池（DRC）中消除了 ArCl 光谱干扰。干扰离子（(40)Ar(35)Cl(+)）通过与甲烷气体的反应被直接去除，在 m/z 75 处的背景信号降低了 100 倍。或者，通过使用分子氧作为反应气体，（75）As(+) 被有效地转化为（75）As(16)O(+)，可以在背景较低的 m/z 91 处检测到。在分析溶液中加入 4%甲醇后，As 或 AsO 的信号强度提高了 3-4 倍。（75）As（CH(4)-DRC 方法）和（75）As(16)O（O(2)-DRC 方法）的定量限（LOQ）分别为 0.8 和 0.3 ng g(-1)，海藻和黄鱼标准参考物质的分析结果与证书值吻合良好。作为我们实验室的常规砷监测方法，它被应用于北京八个不同市场的 119 个高氯食品样品的准确度测定。
