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董会军, 董建芳, 王昕洲, 李义, 赵峰. pH值对HPLC-ICP-MS测定水体中不同形态砷化合物的影响[J]. 岩矿测试, 2019, 38(5): 510-517. DOI: 10.15898/j.cnki.11-2131/td.201808230096
引用本文: 董会军, 董建芳, 王昕洲, 李义, 赵峰. pH值对HPLC-ICP-MS测定水体中不同形态砷化合物的影响[J]. 岩矿测试, 2019, 38(5): 510-517. DOI: 10.15898/j.cnki.11-2131/td.201808230096
DONG Hui-jun, DONG Jian-fang, WANG Xin-zhou, LI Yi, ZHAO Feng. Effect of pH on Determination of Various Arsenic Species in Water by HPLC-ICP-MS[J]. Rock and Mineral Analysis, 2019, 38(5): 510-517. DOI: 10.15898/j.cnki.11-2131/td.201808230096
Citation: DONG Hui-jun, DONG Jian-fang, WANG Xin-zhou, LI Yi, ZHAO Feng. Effect of pH on Determination of Various Arsenic Species in Water by HPLC-ICP-MS[J]. Rock and Mineral Analysis, 2019, 38(5): 510-517. DOI: 10.15898/j.cnki.11-2131/td.201808230096

pH值对HPLC-ICP-MS测定水体中不同形态砷化合物的影响

Effect of pH on Determination of Various Arsenic Species in Water by HPLC-ICP-MS

  • 摘要: 在高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)测定不同形态砷化合物的检测技术中,流动相的pH值是一个关键影响因素。以往较多的研究仅关注了pH值对分离度的影响,通过比较分离度的优劣选择一个适用的pH值。本文采用HPLC-ICP-MS技术测定不同形态的砷化合物,以30mmol/L碳酸氢铵溶液作为流动相,研究了当流动相pH值在6.0~9.7范围内变化时,对砷形态化合物保留时间和峰强度产生的影响,从砷化合物的分离度、灵敏度和分析成本三个方面确定合理的分析方案。结果表明:pH值在6.0~7.5和9.5~9.7范围内,As(Ⅲ)、As(Ⅴ)、一甲基砷(MMA)和二甲基砷(DMA)四种形态的砷化合物的色谱峰分离效果较好;pH值在8.0~9.0范围时,随着pH值的增加,As(Ⅲ)和DMA出峰顺序发生了交换;pH为弱酸性时,砷化合物的灵敏度均较高;pH为偏碱性时,分析周期变短,适用于快速分析。碱性条件下,部分砷化合物与色谱柱结合能力更强,被保留在色谱柱内,使得色谱柱的寿命可能缩短。研究认为:偏酸性的流动相条件,适用于超低浓度(如≤ 10μg/L)的样品分析;偏碱性的流动相条件,具有明显的时间成本和运行成本优势,但要对色谱柱定期维护。

     

    Abstract:
    BACKGROUNDPrevious studies have focused on the effect of pH on separability, choosing an optimal pH by comparing the degree of separation in the determination of different arsenic species by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS).
    OBJECTIVESTo determine an effective analysis program by comparing the separation, sensitivity and analysis coat at different pH.
    METHODSDifferent species of arsenic compounds were determined by HPLC-ICP-MS, using 30mmol/L ammonium bicarbonate solution as the eluent. The retention time and peak strength of arsenic compounds were monitored when the pH of the eluent changed between 6.0 and 9.7.
    RESULTSIn the pH ranges of 6.0-7.5 and 9.5-9.7, the chromatographic peaks of the arsenic compounds were well separated. When the pH value was 8.0-9.0, the peak order of As(Ⅲ) and DMA was exchanged as the pH value increased. When the pH was weakly acidic, the sensitivity of arsenic compounds was higher. When pH was alkaline, the analysis period became shorter and suitable for rapid analysis. About 70% of arsenic compounds in the alkaline eluent combined more strongly to the column and were retained in the column, shortening the life of the column. Acidic eluent was suitable for sample analysis at ultra-low concentrations (e.g. ≤ 10μg/L).
    CONCLUSIONSThe effect of pH of eluent plays a crucial role in the determination of arsenic species by affecting the binding ability of arsenic compounds to chromatographic column. The acidic eluent has a great advantage in sensitivity. The alkaline eluent has obvious advantages of time and operation cost, but it is necessary to pay attention to the maintenance of the chromatographic column.

     

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