Use of ion-molecule reactions and methanol addition to improve arsenic determination in high chlorine food samples by DRC-ICP-MS.
Use of ion-molecule reactions and methanol addition to improve arsenic determination in high chlorine food samples by DRC-ICP-MS.
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DOI：
10.1016/j.talanta.2011.02.026
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发表时间：
2011-05
期刊：
影响因子：
6.1
通讯作者：
Wei Guo;Shenghong Hu;Xiaofang Li;Jian Zhao;Shesheng Jin;Wenjuan Liu;Hongfei Zhang
中科院分区：
文献类型：
--
作者：
Wei Guo;Shenghong Hu;Xiaofang Li;Jian Zhao;Shesheng Jin;Wenjuan Liu;Hongfei Zhang
高氯食品中痕量砷的直接测定因存在ArCl+干扰而变得复杂，且As的第一电离能（9.81eV）较高，导致ICP-MS分析灵敏度较低。干扰离子（40 Ar 35 Cl+）通过与甲烷气体反应直接除去，并且在m/z 75处背景信号降低高达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+，其可以在m/z 91处检测，其中背景低。在分析溶液中加入4%的甲醇，可使As或阿索的弱信号强度提高3-4倍。75 As（CH 4-刚果民主共和国法）和75 As 16 O（O2-刚果民主共和国法）的定量限（LOQ）分别为0.8和0.3ngg-1，海藻和黄花鱼标准参考物质的分析结果与认证值一致。作为本实验室常规砷监测方法，对北京市8个市场的119份高氯食品样品进行了准确度测定。
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 (9.81eV) 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 (40Ar35Cl+) 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,75As+was effectively converted to75As16O+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) for75As (CH4-DRC method) and75As16O (O2-DRC method) was 0.8 and 0.3ngg−1and 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.