Pseudopolarography of copper complexes in seawater using a vibrating gold microwire electrode.
Pseudopolarography of copper complexes in seawater using a vibrating gold microwire electrode.
复制标题
使用振动金微丝电极对海水中的铜络合物进行伪极谱分析。
DOI：
10.1021/jp3019155
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
C. M. G. van den Berg
中科院分区：
文献类型：
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作者：
Kristoff Gibbon;Pascal Salaün;C. M. G. van den Berg
采用振动金微丝电极（VGME）阳极溶出伏安法测定海水中的铜（Cu），其检测限比使用汞电极低得多，可以检测痕量水平的不稳定铜。本文研究了利用VGME对Cu进行伪极谱分析的可能性，并对已知的螯合剂进行了校准。通过应用解吸步骤去除吸附的有机物和多余的阴离子，灵敏度大大提高（15倍）。固体电极受记忆效应影响的臭名昭著的倾向被一个稳定电极响应的测量之间的调节间隔所克服。模型配体，包括EDTA，腐殖质（HS）和谷胱甘肽（天然配体的例子）进行分析，以校准半波移到络合物的稳定性。VGME上的半波移比汞滴电极上的半波移大得多（~2倍），这是由于VGME上的扩散层薄得多（5倍）。实验表明，同样的方法也适用于锌的赝极谱。新方法在爱尔兰海样品中的应用表明，铜存在于几种配合物中，它们都是强结合的，有些出现在伪极谱图的电化学可逆区。在伪极谱图的可逆区还发现了铜的腐殖质络合物。海水中铜的伪极极性图不受样品过滤的影响，也不需要清除溶解氧，这表明该方法可以很容易地用作原位测量系统的一部分。
Copper (Cu) in seawater can be determined by anodic stripping voltammetry using a vibrating gold microwire electrode (VGME) with a much lower limit of detection than using a mercury electrode, enabling detection of labile Cu at trace level. The possibility of pseudopolarography of Cu using the VGME is investigated here and is calibrated against known chelating agents. The sensitivity much (15-fold) improved by application of a desorption step to remove adsorbed organic substances and excess anions. The notorious tendency of solid electrodes to be affected by memory effects was overcome by a conditioning interval between measurements that stabilized the electrode response. Model ligands, including EDTA, humic substances (HS), and glutathione (examples of natural ligands) were analyzed to calibrate the half-wave shift to complex stability. The half-wave shift on the VGME is much greater (~2×) than that on the mercury drop electrode which is attributed to several parameters including a much (5-fold) thinner diffusion layer on the VGME. Experiments showed that the same procedure is suitable for pseudopolarography of zinc. Application of the new method to samples from the Irish Sea showed Cu occurring in several complexes, all strongly bound, and some occurring in the electrochemically reversible region of the pseudopolarogram. The humic substance complex of Cu was also found to occur in the reversible region of the pseudopolarogram. The pseudopolarograms of Cu in seawater were unaffected by sample filtration and did not require purging to remove dissolved oxygen, suggesting that this method can be readily used as part of an in situ measuring system.