Department of Chemistry and Research Laboratory for Analytical Instrument and Electrochemistry Innovation, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Department of Chemistry and Research Laboratory for Analytical Instrument and Electrochemistry Innovation, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Center of Excellence for Innovation in Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Talanta. 2017 Aug 1;170:1-8. doi: 10.1016/j.talanta.2017.03.073. Epub 2017 Mar 30.
The screen-printed carbon electrode (SPCE) modified with various nanoparticles has been studied for using as a working electrode in voltammetric technique. The electrochemical behavior of paraquat on different electrodes was studied by cyclic voltammetry (CV), and then differential pulse voltammetry (DPV) has been employed for trace analysis of paraquat based on redox reaction which the peak current was directly proportional to the concentration of paraquat in the solution. The SPCE modified with carbon nanotube dispersed in Nafion and ethanol (SPCE-CNT/Nafion) gave the best result. Sequential injection-differential pulse voltammetric (SI-DPV) method has been developed for more automated analysis and to reduce chemical consumption. The parameters affecting the SI-DPV system such as step potential, modulation amplitude, flow rate, and concentration of sodium chloride as an electrolyte were studied to improve the sensitivity. Under the optimum condition of the system, i.e., Nafion concentration of 1% (w/v), volume of CNT suspension of 2µL, flow rate of 100µLs, step potential of 5mV, modulation amplitude of 100mV and concentration of sodium chloride of 1M, a linear calibration graph in the range of 0.54-4.30µM with a good R of 0.9955 and a limit of detection of 0.17µM (0.03mgL) were achieved. The proposed system shows high tolerance to some possible interfering ions in natural water, surfactant, and other pesticides. The relative standard deviation (RSD) was 4.2% for 11 replicate measurements with the same electrode. The reproducibility for the preparation of 7 modified electrodes was 2.3% RSD. Recoveries of the analysis were obtained in the range of 82-106%. The developed system can be conveniently applied for analysis without pretreatment of the samples.
已研究了各种纳米粒子修饰的丝网印刷碳电极 (SPCE)，将其用作伏安技术中的工作电极。通过循环伏安法 (CV) 研究了百草枯在不同电极上的电化学行为，然后采用差分脉冲伏安法 (DPV) 基于氧化还原反应对百草枯进行痕量分析，峰电流与溶液中百草枯的浓度成正比。在 Nafion 和乙醇中分散的碳纳米管修饰的 SPCE (SPCE-CNT/Nafion) 给出了最佳结果。为了实现更自动化的分析并减少化学消耗，开发了顺序注射-差分脉冲伏安法 (SI-DPV) 方法。研究了影响 SI-DPV 系统的参数，例如阶跃电位、调制幅度、流速和作为电解质的氯化钠浓度，以提高灵敏度。在系统的最佳条件下，即 Nafion 浓度为 1%（w/v）、2μL CNT 悬浮液体积、流速为 100μLs、阶跃电位为 5mV、调制幅度为 100mV 和氯化钠浓度为 1M，在 0.54-4.30μM 范围内获得了良好的线性校准图，相关系数为 0.9955，检测限为 0.17μM（0.03mgL）。该系统对天然水中的一些可能干扰离子、表面活性剂和其他农药具有较高的容忍度。用相同的电极进行 11 次重复测量的相对标准偏差 (RSD) 为 4.2%。7 个修饰电极的重现性 RSD 为 2.3%。分析回收率在 82-106%范围内。该系统可方便地应用于无需预处理样品的分析。
