Reduction of acid effects on trace element determination in food samples by CH₄ mixed plasma-DRC-MS

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• 作者：Wei Guo^a ; Shenghong Hu^a ; ^{shhu@cug.edu.cn} ; Jiangyi Zhang^b ; Zhaochu Hu^a ; Hongfei Zhang^a ; Yanxin Wang^a
• 关键词：Acid effects ; Trace elements ; Food samples ; CH4&ndash ; Ar mixed plasma-DRC-MS
• 刊名：Talanta
• 出版年：2012
• 期刊代码：106_00399140
• 类别：ch
• 出版时间：15 March, 2012
• 卷：91
• 期：Complete
• 页码：60-64
• 文件大小：586 K

摘要

A robust method for trace element determination in food samples by addition of methane to the plasma of a dynamic reaction cell mass spectrometer (CH₄ mixed plasma-DRC-MS) was developed. Addition of 3 mL min^鈭? methane to Ar-plasma eliminates the signal suppressions of various elements (As, Se, Hg, etc.) due to the high concentration of nitric acid (10%, v/v). The CH₄-Ar mixed plasma may compensate for the plasma cooling effects due to the highly concentrated nitric acid. The interfering polyatomic ions ⁴⁰Ar¹²C⁺, ⁴⁰Ar³⁵Cl⁺ and ⁴⁰Ar⁴⁰Ar⁺ on ⁵²Cr⁺, ⁷⁵As⁺ and ⁸⁰Se⁺ determination were removed effectively using the DRC with CH₄ as the reaction gas. The limits of quantification (LOQ, 10蟽) were 0.35 ng g^鈭?, 0.07 ng g^鈭?, 0.35 ng g^鈭?, 0.07 ng g^鈭?, 0.15 ng g^鈭?, and 0.07 ng g^鈭? for As, Cd, Cr, Hg, Pb and Se, respectively. The proposed method was applied to the determination of these trace elements in four food standard reference materials (NIST1577b, GBW10018, NIST1570a and GBW10016), and the results were in good agreement with the certified values.