Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
Anal Chim Acta. 2015 Sep 10;892:153-9. doi: 10.1016/j.aca.2015.08.022. Epub 2015 Aug 22.
We report the use of silver (Ag)-modified carbon and Ag ultramicroelectrodes (UMEs) for electrochemical detection of nitrate. We investigated several methods for electrodeposition of Ag; our results show that the addition of a complexation agent (ammonium sulfate) in the Ag deposition solution is necessary for electrodeposition of nanostructured Ag that adheres well to the electrode. The electrodeposited Ag on both types of electrodes has branch-like structures that are well-suited for electrocatalytic reduction of nitrate. The use of UMEs is advantageous; the sigmoidal-shaped cyclic voltammogram allows for sensitive detection of nitrate by reducing the capacitive current, as well as enabling easy quantification of the nitrate reduction current. Both cyclic voltammetry and chronoamperometry were used to characterize the electrodes; and independent of the electrochemical interrogation technique, both UMEs were found to have a wide linear dynamic range (4-1000 μM) and a low limit of detection (3.2-5.1 μM). More importantly, they are reusable up to ∼100 interrogation cycles and are selective enough to be used for direct detection of nitrate in a synthetic aquifer sample without any sample pretreatment and/or pH adjustment.
我们报告了使用银（Ag）修饰的碳和 Ag 超微电极（UME）电化学检测硝酸盐。我们研究了几种 Ag 电沉积方法；结果表明，在 Ag 沉积溶液中添加络合剂（硫酸铵）对于电沉积附着在电极上的纳米结构 Ag 是必要的。在这两种类型的电极上电沉积的 Ag 都具有分支状结构，非常适合电催化还原硝酸盐。使用 UME 的优点是；由于可以减少电容电流，因此具有类正弦形的循环伏安图允许对硝酸盐进行灵敏检测，并能够容易地定量硝酸盐还原电流。循环伏安法和计时电流法都用于表征电极；并且，与电化学询问技术无关，两种 UME 都具有较宽的线性动态范围（4-1000 μM）和较低的检测限（3.2-5.1 μM）。更重要的是，它们可重复使用多达约 100 次询问循环，并且足够选择性，可以直接在合成含水层样品中检测硝酸盐，而无需任何样品预处理和/或 pH 调整。
