Department of Inorganic Chemistry, University of Madras, Guindy Maraimalai Campus, Chennai-600025, India.
Analyst. 2013 Oct 7;138(19):5811-8. doi: 10.1039/c3an00941f.
A poly(methylene blue)-modified glassy carbon electrode (PMB/GCE) was fabricated by electropolymerisation of methylene blue on a GCE and further utilized to investigate the electrochemical determination of 4-nitrophenol (4-NP) by cyclic voltammetry (CV), differential pulse voltammetry and chronocoulometry. The morphology of the PMB on GCE was examined using a scanning electron microscope (SEM). An oxidation peak of 4-NP at the PMB modified electrode was observed at 0.28 V, and in the case of bare GCE, no oxidation peak was observed, which indicates that PMB/GCE exhibits a remarkable effect on the electrochemical determination of 4-NP. Due to this remarkable effect of PMB/GCE, a sensitive and simple electrochemical method was proposed for the determination of 4-NP. The effect of the scan rate and pH was investigated to determine the optimum conditions at which the PMB/GCE exhibits a higher sensitivity with a lower detection limit. Moreover, kinetic parameters such as the electron transfer number, proton transfer number and standard heterogeneous rate constant were calculated. Under optimum conditions, the oxidation current of 4-NP is proportional to its concentration in the range of 15-250 nM with a correlation coefficient of 0.9963. The detection limit was found to be 90 nM (S/N = 3). The proposed method based on PMB/GCE is simple, easy and cost effective. To further confirm its possible application, the proposed method was successfully used for the determination of 4-NP in real water samples with recoveries ranging from 97% to 101.6%. The interference due to sodium, potassium, calcium, magnesium, copper, zinc, iron, sulphate, carbonate, chloride, nitrate and phosphate was found to be almost negligible.
一种聚亚甲蓝修饰玻碳电极（PMB/GCE）通过在玻碳电极上电聚合亚甲蓝制备而成，并进一步利用循环伏安法（CV）、差分脉冲伏安法和计时库仑法研究了对硝基苯酚（4-NP）的电化学测定。使用扫描电子显微镜（SEM）检查了 GCE 上 PMB 的形态。在 PMB 修饰电极上观察到 4-NP 的氧化峰在 0.28 V，而在裸 GCE 的情况下，没有观察到氧化峰，这表明 PMB/GCE 对 4-NP 的电化学测定具有显著的影响。由于 PMB/GCE 的这种显著效果，提出了一种用于测定 4-NP 的灵敏而简单的电化学方法。研究了扫描速率和 pH 的影响，以确定 PMB/GCE 具有更高灵敏度和更低检测限的最佳条件。此外，还计算了动力学参数，例如电子转移数、质子转移数和标准异相速率常数。在最佳条件下，4-NP 的氧化电流与其浓度在 15-250 nM 范围内呈正比，相关系数为 0.9963。检测限发现为 90 nM（S/N = 3）。基于 PMB/GCE 的建议方法简单、易用且经济实惠。为了进一步确认其可能的应用，该方法成功用于测定实际水样中的 4-NP，回收率在 97%至 101.6%之间。发现钠离子、钾离子、钙离子、镁离子、铜离子、锌离子、铁离子、硫酸盐、碳酸盐、氯化物、硝酸盐和磷酸盐的干扰几乎可以忽略不计。
