Electrochemical impedance spectroscopy of marmatite–carbon paste electrode in the presence and absence of Acidithiobacillus ferrooxidans

2005 ◽  
Vol 7 (11) ◽  
pp. 1177-1182 ◽  
Author(s):  
Shao-yuan Shi ◽  
Zhao-heng Fang ◽  
Jin-ren Ni
2019 ◽  
Author(s):  
Zhongguo Zheng ◽  
Lisa Schultz ◽  
John Smith

AbstractA highly sensitive DNA electrochemical biosensor was prepared based on multi-walled carbon nanotube/nano-Ag-TiO2 composite membrane. The Ag-TiO2 composite is mixed with a suitable amount of multi-walled carbon nanotubes (MWNT) dispersed in N,N-dimethylformamide to form a uniform and stable mixed solution, which is applied onto the surface of the bare carbon paste electrode. A MWNT/Ag-TiO2 modified carbon paste electrode was prepared. The large specific surface area and good electron transport properties of carbon nanotubes have a good synergistic effect on the good biocompatibility of Ag-TiO2 nanocomposites and excellent adsorption capacity of DNA, which significantly improves the immobilization and DNA hybridization of DNA probes. Detection sensitivity. The preparation of the sensing membrane and the immobilization and hybridization of DNA were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The exogenous glufosinate acetyltransferase gene fragment of transgenic plants was detected by electrochemical impedance spectroscopy. The linear range was 1. 0 × 10 - 11 ∼1. 0 × 10 - 6 mol / L. The detection limit was 3. 12 × 10 - 12 mol / L.


2020 ◽  
Vol 15 (2) ◽  
pp. 93-99
Author(s):  
Hayat EL Ouafy ◽  
Tarik EL Ouafy ◽  
Mustapha Oubenali ◽  
Mohamed Mbarki ◽  
Malika Echajia

The present document reports on the electrocatalytic activity of heavy metals (Copper(II), Nickel(II), Manganese(II) and Lead(II)) modified carbon paste electrodes (HM/CPE) for the paracetamol (Pr) oxidation where its results are compared with carbon paste electrode. The voltammetric behavior of Pr is explored where a sensitive anodic peak has appeared at about 0.27 V (vs. Ag/AgCl/3 M KCl) in 0.1 M Na2SO4 (pH 12). This peak results from the irreversible oxidation of Pr at HM/CPE surface. The catalytic effect was evaluated using cyclic and square wave voltammetry. Electrochemical impedance spectroscopy also confirms our experimental results as the HM/CPE shows the least charge transfer resistance. Also, HM/ CPE can be utilized successfully to ameliorate the electroanalysis of Pr at very weak concentration with excellent sensitivity. The calibration curves were linear from 6.0 · 10-5 to 8.0 · 10-4 mol L-1. The detection limits were found approaching 10-9 mol L-1. Then, the proposed method was applied to detect Pr in river water samples with satisfactory results.


Measurement ◽  
2016 ◽  
Vol 92 ◽  
pp. 524-533 ◽  
Author(s):  
Achour Terbouche ◽  
Siham Lameche ◽  
Chafia Ait-Ramdane-Terbouche ◽  
Djamila Guerniche ◽  
Djahida Lerari ◽  
...  

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
T. Venu Gopal ◽  
Tukiakula Madhusudana Reddy ◽  
P. Shaikshavali ◽  
G. Venkataprasad ◽  
P. Gopal

Abstract A small scale of environmentally hazardous 4-aminophenol can show significant impact on human health. Hence, in the present work, we have designed L-Valine film (Vf) modified carbon paste electrode (Vf/CPE) for the determination of 4-aminophenol. Herein, a facile in-situ L-Valine film was developed by electrochemical polymerization method onto the surface of bare carbon paste electrode (BCPE) with the help of cyclic voltammetry (CV) technique. A two-folds of electrochemical peak current enhancement was achieved at Vf/CPE in comparison with BCPE towards the determination of 4-aminophenol in optimum pH 7.0 of phosphate buffer solution (PBS). This was achieved due to the large surface area and conductive nature of Vf/CPE, which was concluded through the techniques of cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The effect of pH of buffer and scan rate studies were successfully studied. Morphological changes of BCPE and Vf/CPE was studied with the help of scanning electron microscopy (SEM). The formation of Vf on CPE was also analyzed by Fourier transform infrared (FTIR) spectra. Under the optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) values of 4-aminophenol were estimated with the aid of chronoamperometry (CA) technique and was found to be 9.8 μM and 32 μM, respectively. Finally the proposed method was found to have satisfactory repeatability, reproducibility and stability results with low relative standard deviation (RSD) values.


Author(s):  
Ashraf Mahmoud ◽  
Mater Mahnashi ◽  
Samer Abu-Alrub ◽  
Saad Kahatani ◽  
Mohamed El-Wekil

Abstract An innovative and reliable electrochemical sensor was proposed for simple, sensitive and selective determination of F- ions. The sensor is based on the fabrication of porous and electroactive Fe-based metal organic frameworks [MIL-101(Fe)]. It was blended with graphite powder and liquid paraffin oil to from carbon paste electrode (CPE). The MIL-101(Fe)@CPE was characterized using different techniques such as scanning electron microscope, powder X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray, cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry. The MIL-101(Fe)@CPE exhibited two redox peaks (anodic and cathodic) corresponding to Fe3+ and Fe2+, respectively. The determination of F- ions based on the formation of a stable fluoroferric complex with Fe3+/ Fe2+, decreasing the currents of redox species. It was found that the anodic peak current (Ipa) is linearly proportional to the concentration of F- in the range of 0.67-130 µM with a limit of detection (S/N=3) of 0.201 µM. The electrode exhibited good selectivity towards F- detection with no significant interferences from common anions. The as-fabricated sensor was applied for the determination of F- in environmental water samples with recoveries % and RSDs % in the range of 98.1-102.4 % and 2.4-3.7 %, respectively.


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