| 摘要: |
| 基于碱性条件下Fe(II)可催化鲁米诺氧化并产生化学发光的原理,联合顺序注射技术和化学发光法,建立了海水中Fe(II)浓度的高灵敏度自动检测方法和系统。系统主要包括注射泵、选择阀、三通道反应池(自制)、光子计数器及控制模块,在不需要预浓缩条件下,可直接对酸化后海水样品中Fe(II)浓度进行测定。经优化反应条件(包括鲁米诺溶液浓度和pH值、试剂与样品体积比、进样量、进样速度)和测试流程,并采用窗口式检测方式,每次分析所需样品和鲁米诺溶液体积仅分别为80和400 μL,Fe(II)浓度范围为0 - 8.0 nM时,发光强度与Fe(II)浓度呈线性相关,检测限低至4.1 pM,1.0 nM Fe(II)标准溶液连续11次测定的相对标准偏差为3.6%。研究了海水中主要重金属离子和有机配体对测定结果的干扰,结果表明游离态Cu(II)对发光强度影响较大,但天然海水中Cu(II)主要以有机络合态存在,通过在样品中加入有机配体-水杨醛肟与Cu(II)络合,证实有机Cu(II)络合物对Fe(II)测定干扰较小；有机配体(菲啰嗪、乙二胺四乙酸、1-(2-吡啶偶氮)-2-萘酚等)干扰实验表明有机配体与Fe(II)络合可导致发光强度降低,但当其浓度低于Fe(II)浓度50倍时,对发光强度的影响小于9.5%。通过对标准海水样品的分析和实际样品的标准加入实验,验证了方法的准确性。 |
| 关键词: 化学发光法 顺序注射 鲁米诺 Fe(II) 海水 |
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| 基金项目:国家重点研发计划（2022YFC2805504）; 国家自然科学基金项目（42376066）, |
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| A Sequential injection-chemiluminescence detection of Fe(II) in seawater at picomolar levels |
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WANG Lequan, WENG Yuang, WANG Wenpeng, WANG Hu
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State Key Laboratory of Marine Geology,Tongji University
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| Abstract: |
| An automatic and sensitive method for the determination of Fe(II) at the picomolar level in seawater is presented. This method is based on a sequential injection technique and the chemiluminescence analysis of luminol catalyzed by Fe(II) under alkaline conditions. The analyzing system includes an injection pump, an 8-port selector valve, a self-made three-channel reaction cell, a photon counter, and the control module, etc. The optimal conditions for the chemiluminescence reaction (including flow rates, the pH value and concentration of the luminol reagent, the volume of reagent and sample and reaction temperature) and protocol sequence were optimized. The results showed that under the optimal reaction conditions, the detection limit of the system for Fe(II) concentration could be as low as 4.1 pM, and the chemiluminescence intensity was linearly related to Fe(II) concentration in the range of 0 to 8.0 nM. The relative standard deviations for 11 consecutive measurements of 1.0 nM Fe(II) standard solution were 3.6%. The interference of various metal ions was investigated. The results show that the free Cu(II) significantly influences the analysis of Fe(II). However, in natural seawater, Cu(II) exists in the form of organically complexed Cu. It was confirmed that the organic complex of Cu(II) with its ligands has negligible interference with the luminescence intensity. In addition, the interference experiments of organic ligands (EDTA、DTPA、Ferrozine, etc.) show that the increasing concentrations of organic ligands would decrease the chemiluminescence intensity. However, when the concentrations of organic ligands are less than 50 times the Fe (II) concentration, the decrease in the chemiluminescence intensity is no more than 9.5%. The accuracy of the method was validated by analyzing standard seawater solutions and standard addition experiments with seawater samples. |
| Key words: Chemiluminescence method Sequential injection Luminol iron(II) Seawater |