Petovar Barbara, Xhanari Klodian, Finšgar Matjaž
University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova ulica 17, 2000 Maribor, Slovenia.
University of Maribor, Faculty of Chemistry and Chemical Engineering, Smetanova ulica 17, 2000 Maribor, Slovenia; University of Tirana, Faculty of Natural Sciences, Boulevard "Zogu I", 1001 Tirana, Albania.
Anal Chim Acta. 2018 Apr 3;1004:10-21. doi: 10.1016/j.aca.2017.12.020. Epub 2017 Dec 28.
A systematic electrochemical impedance spectroscopy (EIS) analysis at different potentials of an in situ-prepared bismuth-film glassy carbon electrode (BiFE) in 0.1 M acetate buffer solution is reported. This electrode is employed in the square-wave anodic stripping voltammetry (SWASV) technique for the determination of trace amounts of the heavy metals Zn, Cd, and Pb. The method was first validated for detection limit, linear range, sensitivity, precision and accuracy to clearly prove the superior action of BiFE compared with the bare glassy carbon electrode (GCE). Next, in order to investigate the characteristics of this sensor, EIS measurements were carried out at slightly more negative potentials than the potentials at which each individual stripping signal is detected, after the deposition step at different deposition potentials. For comparison, EIS measurements were also performed at open circuit potential. The studied trace metal concentration range (5-20 ppb) did not significantly influence the capacitive and resistive behaviour of the BiFE which explains why the performance of this sensor is superior compared with the bare GCE. The higher sensitivity of the SWASV method for BiFE compared with the bare GCE was explained by the lower polarisation resistance values of the former. Moreover, the potential of zero charge was also determined, and an explanation whether the system is under kinetic- and/or diffusion-controlled process is given.
报道了在0.1 M醋酸盐缓冲溶液中，对原位制备的铋膜玻碳电极（BiFE）在不同电位下进行的系统电化学阻抗谱（EIS）分析。该电极用于方波阳极溶出伏安法（SWASV）技术中，以测定痕量重金属锌、镉和铅。首先对该方法的检测限、线性范围、灵敏度、精密度和准确度进行了验证，以明确证明BiFE相对于裸玻碳电极（GCE）的优越性能。接下来，为了研究该传感器的特性，在不同沉积电位下进行沉积步骤后，在比检测每个单独溶出信号的电位稍负的电位下进行EIS测量。为了进行比较，还在开路电位下进行了EIS测量。所研究的痕量金属浓度范围（5 - 20 ppb）对BiFE的电容和电阻行为没有显著影响，这解释了为什么该传感器的性能优于裸GCE。与裸GCE相比，BiFE的SWASV方法具有更高的灵敏度，这是由于前者的极化电阻值较低。此外，还测定了零电荷电位，并对系统是处于动力学控制和/或扩散控制过程给出了解释。
