Redox kinetic measurements of glutathione at the mercury electrode by means of square-wave voltammetry. The role of copper, cadmium and zinc ions

2004 ◽  
Vol 65 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Mitko Mladenov ◽  
Valentin Mirčeski ◽  
Icko Gjorgoski ◽  
Blagoja Jordanoski
Keyword(s):  
Square Wave Voltammetry ◽  
Mercury Electrode ◽  
Zinc Ions ◽  
Kinetic Measurements ◽  
Square Wave ◽  
Wave Voltammetry

scholarly journals Quantitative determination of glycyrrhizinic acid by square-wave voltammetry and high-pressure liquid chromatography

2003 ◽  
Vol 48 ◽  
pp. 3-8
Author(s):  
Aneta Dimitrovska ◽  
Valentin Mircevski ◽  
Svetlana Kulevanova
Keyword(s):  
High Pressure ◽  
Quantitative Determination ◽  
Electrode Surface ◽  
Square Wave Voltammetry ◽  
Mercury Electrode ◽  
Voltammetric Method ◽  
Square Wave ◽  
Glycyrrhizinic Acid ◽  
Wave Voltammetry

Novel adsorptive stripping square-wave voltammetric method as well as a new high-pressure liquid chromatographic method for direct determination of glycyrrhizinic acid in dosage pharmaceutical preparation, used against virus infections, have been developed. Glycyrrhizinic acid is an electrochemically active compound, which undergoes irreversible reduction on a mercury electrode surface in an aqueous medium. Its redox properties were studied thoroughly by means of square-wave voltammetry, as one of the most advanced electroanalytical technique. The voltammetric response depends mainly on the pH of the medium, composition of the supporting electrolyte, as well as the parameters of the excitement signal. It was also observed that the voltammetric properties strongly depend on the accumulation time and potential, revealing significant adsorption of glycyrrhizinic acid onto the mercury electrode surface. Upon this feature, an adsorptive stripping voltammetric method for quantitative determination of glycyrrhizinic acid was developed. A simple, sensitive and precise reversed phase HPLC method with photodiode array UV detection has also been developed, mainly for comparison and conformation of the results obtained with the voltammetric method.

Electrochemical studies of ganciclovir as the adsorbed catalyst on mercury electrode

2009 ◽  
Vol 74 (10) ◽  
pp. 1455-1466 ◽  
Author(s):  
Sławomira Skrzypek ◽  
Agnieszka Nosal-Wiercińska ◽  
Witold Ciesielski
Keyword(s):  
Square Wave Voltammetry ◽  
Mercury Electrode ◽  
Antiviral Drug ◽  
Linear Sweep Voltammetry ◽  
Protonated Form ◽  
Catalytic Method ◽  
Square Wave ◽  
Mercury Surface ◽  
Capacity Curves ◽  
Wave Voltammetry

Although ganciclovir (gan) as a purine analogue is a compound of biological interest (antiviral drug), it has been rarely electrochemically studied. In this paper surface catalytic electrode mechanism based on the hydrogen evolution reaction is analyzed under conditions of square-wave voltammetry and differential capacity curves of double layer measurements. The electrode mechanism is assumed to involve a preceding chemical reaction in which the adsorbed catalyst (ganads) is protonated at the electrode surface, i.e., ganads + H+aq → ganH+ads. The protonated form of the catalyst (ganH+ads) is irreversibly reduced at potential about –1.35 V vs Ag|AgCl, yielding the initial form of the catalyst and atomic hydrogen, i.e., ganH+ads + e → ganads + Haq. Changes of zero charge potential and surface tension point to the adsorption of ganciclovir molecule directed with guanine group to the mercury surface and suggests that ganciclovir molecules are not placed flat on the mercury surface. The effect of adsorption on mercury electrode was studied in detail in respect to analytical usefulness of the obtained results. A new catalytic method for voltammetric determination of ganciclovir was developed. The detection and quantification limits were 1.3 × 10–7 and 4.3 × 10–7 mol l–1 for square-wave voltammetry, and 1.4 × 10–7 and 4.7 × 10–7 mol l–1 for linear-sweep voltammetry.

New Approach to Electrode Kinetic Measurements in Square-Wave Voltammetry: Amplitude-Based Quasireversible Maximum

2013 ◽  
Vol 85 (11) ◽  
pp. 5586-5594 ◽  
Author(s):  
Valentin Mirceski ◽  
Eduardo Laborda ◽  
Dariusz Guziejewski ◽  
Richard G. Compton
Keyword(s):  
Square Wave Voltammetry ◽  
Kinetic Measurements ◽  
New Approach ◽  
Square Wave ◽  
Wave Voltammetry

Square wave voltammetry at the dropping mercury electrode: theory

1977 ◽  
Vol 49 (13) ◽  
pp. 1899-1903 ◽  
Author(s):  
J. H. Christie ◽  
John A. Turner ◽  
R. A. Osteryoung
Keyword(s):  
Square Wave Voltammetry ◽  
Mercury Electrode ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Dropping Mercury Electrode

scholarly journals The mechanism of azide activation of polyphenol oxidase II from tobacco.

2002 ◽  
Vol 49 (4) ◽  
pp. 1029-1035 ◽  
Author(s):  
Chunhua Shi ◽  
Qingliang Liu ◽  
Ya Dai ◽  
Yongshu Xie ◽  
Xiaolong Xu
Keyword(s):  
Polyphenol Oxidase ◽  
Active Site ◽  
Square Wave Voltammetry ◽  
Nitro Blue Tetrazolium ◽  
Copper Proteins ◽  
Tobacco Leaves ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Blue Tetrazolium

So far, azide has been consistently reported to act as an inhibitor of metal enzymes, especially copper proteins. The present work shows that azide can also act as an activator of polyphenol oxidase II (PPO II) from tobacco leaves. From the square-wave voltammetry of native PPO II, peroxide-PPO II complex and azide-PPO II complex, the reduction of nitro blue tetrazolium by the enzymes and activation of PPO II by peroxide it follows that the binding of azide to PPO II induces the formation of CuO(2)(2-)Cu in the active site of PPO II from CuO(2)(-)Cu in native PPO II. The reason for azide acting as an activator can be attributed to azide complexing with PPO II, thus inducing the formation of CuO(2)(2-)Cu, which is the active site of the peroxide-PPO II complex in which peroxide plays the role of activator.

Square wave voltammetry at the dropping mercury electrode: experimental

1977 ◽  
Vol 49 (13) ◽  
pp. 1904-1908 ◽  
Author(s):  
John A. Turner ◽  
J. H. Christie ◽  
M. Vukovic ◽  
R. A. Osteryoung
Keyword(s):  
Square Wave Voltammetry ◽  
Mercury Electrode ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Dropping Mercury Electrode
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