In Situ Electrochemical Impedance Spectroscopic Method for Determination of Surface Roughness and Morphological Convexity

2021 ◽  
pp. 10025-10033
Author(s):  
Rama Kant ◽  
Himanshi Goel
Keyword(s):  
Surface Roughness ◽  
Electrochemical Impedance ◽  
Spectroscopic Method ◽  
Electrochemical Impedance Spectroscopic

A Facile In-Situ Development of L-Valine Film onto the Surface of Carbon Paste Electrode Towards the Detection of Environmentally Hazardous 4-Amino Phenol

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
T. Venu Gopal ◽  
Tukiakula Madhusudana Reddy ◽  
P. Shaikshavali ◽  
G. Venkataprasad ◽  
P. Gopal
Keyword(s):  
Cyclic Voltammetry ◽  
Carbon Paste Electrode ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Small Scale ◽  
Carbon Paste ◽  
Relative Standard ◽  
Paste Electrode

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.

Research developments in carbon materials based sensors for determination of hormones

2021 ◽  
Author(s):  
Jamballi G. Manjunatha ◽  
Girish Tigari ◽  
Hareesha Nagarajappa ◽  
Nambudumada S. Prinith
Keyword(s):  
Carbon Materials ◽  
Electrochemical Sensors ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Supporting Electrolyte ◽  
Electroanalytical Methods ◽  
Repeatability And Reproducibility ◽  
Electrochemical Impedance Spectroscopic ◽  
Structural Aspects

Various carbon-based sensors (graphene, carbon nanotubes, graphite, pencil graphite, glassy carbon, etc.) have distinctive behavior and a broad range of importance for identifying sex hormones like estriol, estradiol, estrone, progesterone, and testosterone. The current review emphasizes voltammetric, amperometric, and electrochemical impedance spectroscopic methods for detecting some of these hormones. The existence, structural aspects, nature, and biological importance of each hormone were analyzed in detail and their analysis with different electroanalytical methods was considered. Unique methodologies and innovations of electrochemical sensors for hormones based on carbon materials modified by different agents were examined. In this review, the interaction among various sensor materials and analytes in different supporting electrolyte media is premeditated. The most important significances of the electroanalytical methodologies were discussed based on sensor selectivity, sensitivity, stability, the limit of detection, repeatability, and reproducibility.

On-Line Determination of Reaction Completion in a Closed-Loop Hydrogenator Using NIR Spectroscopy

1998 ◽  
Vol 52 (1) ◽  
pp. 17-21 ◽  
Author(s):  
Howard W. Ward ◽  
S. Sonja Sekulic ◽  
Michael J. Wheeler ◽  
Geraldine Taber ◽  
Frank J. Urbanski ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectroscopic Method ◽  
Nir Spectroscopy ◽  
Hydrogenation Reaction ◽  
Partial Least Squares Model ◽  
Chromatographic Procedure ◽  
On Line ◽  
Palladium On Carbon

An on-line near-infrared (NIR) spectroscopic method has been developed to determine in situ the endpoint of a bulk pharmaceutical hydrogenation reaction in a loop hydrogenator. This hydrogenation employs a 5% palladium-on-carbon catalyst with tetrahydrofuran (THF) as the reaction solvent. The traditional test for monitoring the endpoint of the hydrogenation is a gas chromatographic procedure that requires an estimated 60 min from the time a sample is taken to the point where the analysis results become available. The use of NIR spectroscopy in an on-line mode of operation allows spectra to be collected every 2 min and thereby significantly improves response time and result availability. The need for obtaining results in “real time” stems from the creation of undesired side products if the reaction is allowed to continue past the optimal endpoint. If the reaction is not stopped before these side products reach a level of approximately 0.8% (wt/wt), the batch requires additional purification at considerable time and cost. A partial least-squares model was constructed, validated, and successfully used to determine the endpoint of subsequent batches.

scholarly journals Facile Fabrication and Properties of Super-hydrophobic MgAl-LDH Films With Excellent Corrosion Resistance on AZ31 Magnesium Alloy

2021 ◽  
Vol 8 ◽  
Author(s):  
Xing Han ◽  
Jia Hu ◽  
Yong-Qin Wang ◽  
Tian-Bing Xiao ◽  
Wei Xia ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Immersion Test ◽  
Contact Angles ◽  
Az31 Magnesium Alloy ◽  
Water Contact ◽  
Double Hydroxides

A super-hydrophobic anti-corrosion film was facilely prepared via in situ growth of layered double hydroxides (LDHs) on the etched AZ31 magnesium alloy and then modification by 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (PFOTMS) in this work. The morphology, structure, composition, surface roughness and water contact angles (WCA), and the anti-corrosion performance of the samples were investigated. The results revealed that the micro/nano hierarchical surface morphology of the films was composed of island structures obtained after chemical etching and MgAl-LDH nanowalls grown in situ. The best hydrophobicity (CA = 163°) was obtained on the MgAl-LDHs with the maximum surface roughness. Additionally, the potentiodynamic polarization, electrochemical impedance spectroscopy, and immersion test indicated that the super-hydrophobic LDH films provided better corrosion resistance to AZ31 magnesium alloy due to the double-protection derived from the LDHs and super-hydrophobic properties. Furthermore, the contact angle could be kept at above 140° after dipped in 3.5 wt% NaCl solution for 6 days.

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