Determination of arsenic and antimony in seawater by voltammetric and chronopotentiometric stripping using a vibrated gold microwire electrode.
Determination of arsenic and antimony in seawater by voltammetric and chronopotentiometric stripping using a vibrated gold microwire electrode.
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DOI：
10.1016/j.aca.2012.08.013
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发表时间：
2012-10
影响因子：
6.2
通讯作者：
Pascal Salaün;K. B. Gibbon-Walsh;Georgina M. S. Alves;H. Soares;C. M. G. van den Berg
中科院分区：
文献类型：
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作者：
Pascal Salaün;K. B. Gibbon-Walsh;Georgina M. S. Alves;H. Soares;C. M. G. van den Berg
As0/AsIII和Sb0/SbIII在金电极上的氧化电位非常接近，这是因为它们具有相似的化学组成。海水中砷含量低(10-20 nm)，Sb出现在∼为As的0.1倍。本文介绍了用实心金微丝电极电分析海水中无机砷和无机锑的方法。在pH=≤2和pH=8的条件下，采用振动金微丝电极进行了阳极溶出伏安法和计时电位法的研究。在振动下，直径为5μm的线材上的扩散层尺寸为0.7μm，在2min和10min的沉积时间下，对AsIII和Sb III的检测下限分别低于0.1 nm。AsIII和SbIII可在酸性条件下(加入联氨后)或在中性pH下测定。在后一种情况下，As0到AsIII的氧化被发现是通过一个短暂的AsIII物种进行的。这种物种在金电极上的吸附在SbIII扩散的电位下用于选择性沉积AsIII。加入EDTA消除了分析AsIII时锰的干扰作用。需要实施解吸步骤以进行SbII分析。用EDEP=−1V测定总无机砷(IAS=AsV+AsIII)，在pH=1.6<；2时，无SB或单甲基亚砷酸干扰。用EDEP=−1.8V测定总无机锑(ISb=SbV+SbⅢ)，无砷干扰。这些方法在爱尔兰海(利物浦湾)的样本中进行了测试。ASIII是在抽样后立即在船上确定的。砷的浓度范围为0.44~1.56 nm，且沿海较高。SbIII低于检测下限(0.1 nM SbIII)，IAS为8~25 nm，ISB为0.5~1.7 nm。
The oxidation potentials of As0/AsIIIand Sb0/SbIIIon the gold electrode are very close to each other due to their similar chemistry. Arsenic concentration in seawater is low (10–20nM), Sb occurring at ∼0.1 time that of As. Methods are shown here for the electroanalytical speciation of inorganic arsenic and inorganic antimony in seawater using a solid gold microwire electrode. Anodic stripping voltammetry (ASV) and chronopotentiometry (ASC) are used at pH≤2 and pH 8, using a vibrating gold microwire electrode. Under vibrations, the diffusion layer size at a 5μm diameter wire is 0.7μm. The detection limits for the AsIIIand SbIIIare below 0.1nM using 2min and 10min deposition times respectively. AsIIIand SbIIIcan be determined in acidic conditions (after addition of hydrazine) or at neutral pH. In the latter case, oxidation of As0to AsIIIwas found to proceed through a transient AsIIIspecies. Adsorption of this species on the gold electrode at potentials where SbIIIdiffused away is used for selective deposition of AsIII. Addition of EDTA removes the interfering effect of manganese when analysing AsIII. Imposition of a desorption step for SbIIIanalysis is required. Total inorganic arsenic (iAs=AsV+AsIII) can be determined without interference from Sb nor mono-methyl arsenious acid (MMA) at 1.6<pH<2 using Edep=−1V. Total inorganic antimony (iSb=SbV+SbIII) is determined at pH 1 using Edep=−1.8V without interference by As. The methods were tested in samples from the Irish Sea (Liverpool Bay). AsIIIwas determined on-board ship immediately after sampling. AsIIIconcentrations were found to range from 0.44 to 1.56nM and were higher near the coast. SbIIIwas below the detection limit (<0.1nM SbIII), iAs was comprised between 8 and 25nM while iSb varied from 0.5 to 1.7nM.