Ion-Transfer Voltammetry of Perfluoroalkanesulfonates and Perfluoroalkanecarboxylates: Picomolar Detection Limit and High Lipophilicity
Ion-Transfer Voltammetry of Perfluoroalkanesulfonates and Perfluoroalkanecarboxylates: Picomolar Detection Limit and High Lipophilicity
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DOI：
10.1021/ac5027836
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发表时间：
2014-11-18
影响因子：
7.4
通讯作者：
Amemiya, Shigeru
中科院分区：
文献类型：
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作者：
Garada, Mohammed B.;Kabagambe, Benjamin;Amemiya, Shigeru
在这里，我们报告的全氟烷烃磺酸盐和全氟烷烃羧酸盐在增塑聚合物膜和水之间的界面上的离子转移伏安法，使这些持久性的环境污染物与不利的健康影响的超灵敏检测。全氟烷基含氧阴离子的离子转移循环伏安图是通过使用类似于1 μ m厚的聚氯乙烯膜与2-硝基苯基辛基醚增塑获得的。的循环伏安数值分析，以确定正式的离子转移电位作为衡量离子亲脂性。形式电位的分段分析表明，与具有相同链长的烷基磺酸盐相比，全氟烷基磺酸盐的亲脂性高10（4）倍，这是由于过氧化物对降低相邻磺酸盐基团的电子密度的诱导作用，从而削弱其水合作用。片段分析还表明，全氟烷基和相同长度的烷基的亲脂性几乎相同，并随长度而变化。有利的是，全氟辛烷磺酸盐的高亲脂性允许其在1 mM含水支持电解质存在下在50 pM下进行溶出伏安检测，类似于10（7）倍高的浓度。值得注意的是，全氟辛烷磺酸盐的检测限对于电化学传感器来说是前所未有的低，并且低于美国环境保护署设定的饮用水中的最低报告水平。相比之下，全氟烷烃羧酸的伏安检测不仅受到羧酸酯基团的亲油性较低的影响，而且还受到其在伏安离子-电子转换过程中在底层聚（3-辛基噻吩）-修饰的金电极处的氧化脱羧的影响。
Here we report on ion-transfer voltammetry of perfluoroalkanesulfonates and perfluoroalkanecarboxylates at the interface between a plasticized polymer membrane and water to enable the ultrasensitive detection of these persistent environmental contaminants with adverse health effects. The ion-transfer cyclic voltammograms of the perfluoroalkyl oxoanions are obtained by using a similar to 1 mu m thick poly(vinyl chloride) membrane plasticized with 2-nitrophenyl octyl ether. The cyclic voltammograms are numerically analyzed to determine formal ion-transfer potentials as a measure of ion lipophilicity. The fragmental analysis of the formal potentials reveals that the 10(4) times higher lipophilicity of a perfluoroalkanesulfonate in comparison to the alkanesulfonate with the same chain length is due to the inductive effect of perfluorination on lowering the electron density of the adjacent sulfonate group, thereby weakening its hydration. The fragmental analysis also demonstrates that the lipophilicities of perfluoroalkyl and alkyl groups with the same length are nearly identical and vary with the length. Advantageously, the high lipophilicity of perfluorooctanesulfonate allows for its stripping voltammetric detection at 50 pM in the presence of 1 mM aqueous supporting electrolytes, a similar to 10(7) times higher concentration. Significantly, this detection limit for perfluorooctanesulfonate is unprecedentedly low for electrochemical sensors and is lower than its minimum reporting level in drinking water set by the U.S. Environmental Protection Agency. In comparison, the voltammetric detection of perfluoroalkanecarboxylates is compromised not only by the lower lipophilicity of the carboxylate group but also by its oxidative decarboxylation at the underlying poly(3-octylthiophene)-modified gold electrode during voltammetric ion-to-electron transduction.