Abstract

Background

The importance of recognizing and quantifying chemical anions/cations found in various types of samples, including environmental and biological samples, has been extensively studied. Recent findings suggest the possibility of health risks caused by organic compound dimethylarsinic acid (DMAs) rather than its inorganic arsenic metabolite.

Objective

This article aims to fabricate polymeric-membrane electrochemical sensors with high sensitivity and selectivity for the cacodylic acid sodium salt dimethylarsinate (DMAs) based on silver diethyldithiocarbamate (AgDDTC) and Cu^IIphthalocyanine (CuPC) as novel neutral carriers and their applications.

Method

DMAs calibration relations and titrations were carried out using a potentiometric workstation equipped with a double-junction reference electrode, in conjunction with the fabricated working electrodes.

Results

Sensors revealed fast and stable anionic response with near-Nernstian slopes (−38.6 ± 0.9 and −31.5 ± 0.6 mV/decade), within concentration ranges (1.7 × 10⁻⁵ –1.0 × 10⁻² and 3.0 × 10⁻⁵ –1.0 × 10⁻² M) and detection limits (1.0 × 10⁻⁵ and 1.6 × 10⁻⁵ M) for AgDDTC- and CuPC-based sensors, respectively. Sensors are characterized by extended life-time, signal stability, high precision and short response times. Selectivity for the cacodylate anion over most common anions was tested for the proposed electrodes. Sensors were satisfactorily applied for DMAs quantification in biological matrices with recoveries ranging between 96.2 and 99.0%. Membrane sensors were interfaced with a flow-through system for continuous monitoring of DMAs. The sensors were tested for the assay of different amino acids based on their reaction with cacodylate, where reaction end points were monitored with the proposed electrodes using direct potentiometric determination and flow injection analysis (FIA).

Conclusions

Potentiometric ion-selective PVC-membrane electrodes based on silver diethyldithiocarbamate (AgDDTC) and CuIIphthalothyanine (CuPC) provide adequate and reliable means for the determination of dimethylarsenate anion (cacodylate anion, DMAs). These membrane electrodes are easy to manufacture, they have the advantages of high selectivity and sensitivity, broad dynamic ranges, low detection limits, quick response times and cost effectiveness. Such properties make these sensors suitable for the assay of DMAs levels in aqueous solutions by direct potentiometry, flow injection and potentiometric titration, as well as in monitoring of the titration end points of the reactions between various amino acids and DMAs anion in aqueous solutions.

Highlights

Simple electrochemical membranes for dimethylarsinate (DMAs) were prepared, based on diethyldithiocarbamate (AgDDTC) and CuIIphthalocyanine (CuPC). - DMAs sensors were fabricated in two different modules: batch (for static) and flow-through (for hydrodynamic) approaches. - Levels of DMAs were determined in spiked biological samples. - AgDDTC-based sensors were successfully applied in the determination of several amino acids via potentiometric titration with DMAs.

中文翻译：

---

二甲胂酸传感器及其在生物样品中氨基酸水平测定中的应用

摘要

背景

已经广泛研究了识别和量化在各种类型的样品（包括环境和生物样品）中发现的化学阴离子/阳离子的重要性。最近的研究结果表明，有机化合物二甲基胂酸 (DMA) 而非其无机砷代谢物可能导致健康风险。

客观的

^{本文旨在以二乙基二硫代氨基甲酸银 (AgDDTC) 和 Cu II}酞菁 (CuPC) 作为新型中性载体的二甲基胂酸钠盐 (DMAs) 制备具有高灵敏度和选择性的聚合物膜电化学传感器及其应用。

方法

DMA 校准关系和滴定使用配备双结参比电极的电位计工作站与制造的工作电极一起进行。

结果

在浓度范围（1.7 × 10 ^-5 -1.0 × 10 ^-2和 3.0 × 10 ^-5 -1.0 × 10 ^-2 M）和检测限（1.0 × 10 ^-5和 1.6 × 10 ^-5M) 分别用于基于 AgDDTC 和 CuPC 的传感器。传感器的特点是使用寿命长、信号稳定、精度高和响应时间短。对于所提出的电极，测试了二甲胂酸盐阴离子相对于大多数常见阴离子的选择性。传感器令人满意地应用于生物基质中的 DMA 定量，回收率在 96.2 和 99.0% 之间。膜传感器与流通系统连接，用于连续监测 DMA。根据传感器与二甲胂酸盐的反应，对传感器进行了不同氨基酸的测定，其中使用直接电位测定和流动注射分析 (FIA) 使用建议的电极监测反应终点。

结论

基于二乙基二硫代氨基甲酸银 (AgDDTC) 和 CuII酞菁 (CuPC) 的电位离子选择性 PVC 膜电极为测定二甲基砷酸根阴离子（二甲胂酸根阴离子，DMA）提供了充分且可靠的方法。这些膜电极易于制造，具有高选择性和灵敏度、宽动态范围、低检测限、快速响应时间和成本效益等优点。这些特性使这些传感器适用于通过直接电位法、流动注射和电位滴定法测定水溶液中的 DMAs 水平，以及监测水溶液中各种氨基酸和 DMAs 阴离子反应的滴定终点。

强调

基于二乙基二硫代氨基甲酸酯 (AgDDTC) 和铜酞菁 (CuPC) 制备了用于二甲基胂酸盐 (DMA) 的简单电化学膜。- DMA 传感器在两个不同的模块中制造：批处理（用于静态）和流通（用于流体动力）方法。- 测定加标生物样品中的 DMA 水平。- 基于 AgDDTC 的传感器已成功应用于通过 DMA 的电位滴定测定多种氨基酸。