Department of Chemistry, School of Engineering Science in Chemistry, Biochemistry and Health, KTH Royal Institute of Technology, SE-100 44Stockholm, Sweden.
UCAM-SENS, Universidad Católica San Antonio de Murcia, UCAM HiTech, Avda. Andres Hernandez Ros 1, 30107Murcia, Spain.
Anal Chem. 2023 Feb 28;95(8):4180-4189. doi: 10.1021/acs.analchem.2c05307. Epub 2023 Feb 1.
We present a methodology for the detection of dissolved inorganic phosphorous (DIP) in seawater using an electrochemically driven actuator-sensor system. The motivation for this work stems from the lack of tangible solutions for the in situ monitoring of nutrients in water systems. It does not require the addition of any reagents to the sample and works under mild polarization conditions, with the sample confined to a thin-layer compartment. Subsequent steps include the oxidation of polyaniline to lower the pH, the delivery of molybdate via a molybdenum electrode, and the formation of an electroactive phosphomolybdate complex from DIP species. The phosphomolybdate complex is ultimately detected by either cyclic voltammetry (CV) or square wave voltammetry (SWV). The combined release of protons and molybdate consistently results in a sample pH < 2 as well as a sufficient excess of molybdate, fulfilling the conditions required for the stoichiometric detection of DIP. The current of the voltammetric peak was found to be linearly related to DIP concentrations between 1 and 20 μM for CV and 0.1 and 20 μM for SWV, while also being selective against common silicate interference. The analytical application of the system was demonstrated by the validated characterization of five seawater samples, revealing an acceptable degree of difference compared to chromatography measurements. This work paves the way for the future DIP digitalization in environmental waters by in situ electrochemical probes with unprecedented spatial and temporal resolution. It is expected to provide real-time data on anthropogenic nutrient discharges as well as the improved monitoring of seawater restoration actions.
我们提出了一种利用电化学驱动执行器-传感器系统检测海水中溶解无机磷（DIP）的方法。这项工作的动机源于缺乏用于原位监测水系统中营养物质的切实可行的解决方案。它不需要向样品中添加任何试剂，并且在温和的极化条件下工作，样品被限制在薄层隔室中。随后的步骤包括将聚苯胺氧化以降低 pH 值，通过钼电极输送钼酸盐，以及在 DIP 物种形成电活性的磷钼酸盐络合物。最终通过循环伏安法（CV）或方波伏安法（SWV）检测磷钼酸盐络合物。质子和钼酸盐的联合释放始终导致样品 pH 值<2 以及钼酸盐的足够过量，满足 DIP 化学计量检测的条件。发现 CV 中伏安峰电流与 1 至 20 μM 之间的 DIP 浓度呈线性关系，SWV 中为 0.1 至 20 μM，同时对常见的硅酸盐干扰具有选择性。该系统的分析应用通过对五个海水样本的验证特征得到了证明，与色谱测量相比，结果具有可接受的差异程度。这项工作为未来通过具有前所未有的空间和时间分辨率的原位电化学探针实现环境水中的 DIP 数字化铺平了道路。它有望提供有关人为营养物质排放的实时数据，并改善对海水恢复行动的监测。
