Electrochemical reduction of ketoprofen and its determination in pharmaceutical dosage forms by differential-pulse polarography

The Analyst ◽  
1984 ◽  
Vol 109 (1) ◽  
pp. 57 ◽  
Author(s):  
Lawrence Amankwa ◽  
Leslie G. Chatten
Keyword(s):  
Electrochemical Reduction ◽  
Differential Pulse ◽  
Dosage Forms ◽  
Differential Pulse Polarography ◽  
Pharmaceutical Dosage Forms ◽  
Pulse Polarography

Electrochemical reduction of benzenediazonium salts in aprotic medium

1989 ◽  
Vol 54 (6) ◽  
pp. 1496-1507
Author(s):  
Pavel Janderka ◽  
Igor Cejpek
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Reduction ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Reduction Mechanism ◽  
Aprotic Medium ◽  
Pulse Polarography ◽  
Dc Polarography ◽  
Donor Numbers

DC polarography, TAST polarography, differential pulse polarography, polarography with superimposed alternating current, slow cyclic voltammetry with a hanging Hg drop electrode and a Pt electrode, rapid cyclic voltammetry with a hanging Hg drop, and coulometry were used to study the electrochemical reduction of p-methoxy- and p-nitrobenzenediazonium cations in aprotic medium. A reduction mechanism involving two separate one-electron steps is proposed, the first of which being complicated by adsorption and follow-up chemical reaction leading to evolution of nitrogen. The basicity of the aprotic solvents, expressed by donor numbers according to Gutman, influences the reduction mechanism of these cations.

Polarographic and voltammetric determination of 6-nitrobenzimidazole and mechanism of its electrochemical reduction

2009 ◽  
Vol 74 (10) ◽  
pp. 1443-1454 ◽  
Author(s):  
Dana Deýlová ◽  
Jiří Barek ◽  
Vlastimil Vyskočil
Keyword(s):  
Electrochemical Reduction ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Optimal Conditions ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Constant Potential ◽  
Pulse Voltammetry

Optimal conditions were found for the determination of 6-nitrobenzimidazole by tast polarography (at 1 × 10–4–1 × 10–6 mol l–1), by differential pulse polarography at dropping mercury electrode (at 1 × 10–4–1 × 10–7 mol l–1), and by differential pulse voltammetry at hanging mercury drop electrode (at 1 × 10–4–1 × 10–8 mol l–1). Practical applicability of the developed methods was verified on the determination of 6-nitrobenzimidazole in drinking water (at 10–8 mol l–1). Coulometry at constant potential and cyclic voltammetry were used for elucidation of the mechanism of electrochemical reduction.

Influence of substituents on electrochemical reduction potentials of benzenediazonium salts

1989 ◽  
Vol 54 (12) ◽  
pp. 3135-3143 ◽  
Author(s):  
Pavel Janderka ◽  
Igor Cejpek
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Reduction ◽  
Linear Correlation ◽  
Structural Parameters ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Reduction Potentials ◽  
Pulse Polarography ◽  
Substituent Constants ◽  
Influence Of Substituents

TAST polarography, differential pulse polarography, and cyclic voltammetry on a hanging mercury drop and on a platinum disc were employed to measure the electrochemical reduction potentials of nine para substituted benzenediazonium salts in dimethylformamide. A satisfactory linear correlation was obtained between the potentials of the adsorption prewave and the substituent constants σ+p. The influence of substituents on some structural parameters was studied by using the CNDO/2 method for both a closed and a opened shell.

Determination of platinum in biological material by differential pulse polarography: Analysis in urine, plasma and tissue following sample combustion

1983 ◽  
Vol 48 (10) ◽  
pp. 2903-2908 ◽  
Author(s):  
Viktor Vrabec ◽  
Oldřich Vrána ◽  
Vladimír Kleinwächter
Keyword(s):  
Biological Material ◽  
Biological Fluid ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Linear Calibration ◽  
Catalytic Current ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode

A method is described for determining total platinum content in urine, blood plasma and tissues of patients or experimental animals receiving cis-dichlorodiamineplatinum(II). The method is based on drying and combustion of the biological material in a muffle furnace. The product of the combustion is dissolved successively in aqua regia, hydrochloric acid and ethylenediamine. The resulting platinum-ethylenediamine complex yields a catalytic current at a dropping mercury electrode allowing to determine platinum by differential pulse polarography. Platinum levels of c. 50-1 000 ng per ml of the biological fluid or per 0.5 g of a tissue can readily be analyzed with a linear calibration.

Polarography of N,N-dimethyl-4-amino-4'-hydroxyazobenzene in water-methanol mixtures

1985 ◽  
Vol 50 (3) ◽  
pp. 712-725 ◽  
Author(s):  
Jiří Barek ◽  
Lubomír Kelnar
Keyword(s):  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Polarographic Reduction ◽  
Reduction Mechanism ◽  
Pulse Polarography ◽  
Methanol Medium

The polarographic reduction of N,N-dimethyl-4-amino-4'-hydroxyazobenzene in water-methanol medium was investigated. Evidence is presented for adsorption of the depolarizer on the electrode, and a reduction mechanism is proposed. Conditions are indicated for the determination of this compound in the concentration range 10-4-10-6 mol/l by d.c. polarography, 10-5 to 3 . 10-7 mol/l by Tast polarography, and 10-5-3 . 10-8 mol/l by differential pulse polarography.

Polarographic and voltammetric determination of 6-mercaptopurine and 6-thioguanine

1986 ◽  
Vol 51 (11) ◽  
pp. 2466-2472 ◽  
Author(s):  
Jiří Barek ◽  
Antonín Berka ◽  
Ludmila Dempírová ◽  
Jiří Zima
Keyword(s):  
Detection Limit ◽  
Differential Pulse Voltammetry ◽  
Detection Limits ◽  
Differential Pulse ◽  
Voltammetric Determination ◽  
Differential Pulse Polarography ◽  
Hanging Mercury Drop Electrode ◽  
Pulse Polarography ◽  
Pulse Voltammetry

Conditions were found for the determination of 6-mercaptopurine (I) and 6-thioguanine (II) by TAST polarography, differential pulse polarography and fast-scan differential pulse voltammetry at a hanging mercury drop electrode. The detection limits were 10-6, 8 . 10-8, and 6 . 10-8 mol l-1, respectively. A further lowering of the detection limit to 2 . 10-8 mol l-1 was attained by preliminary accumulation of the determined substances at the surface of a hanging mercury drop.

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