The polarographic and voltammetric determination of the 4'-haloderivatives of N,N-dimethyl-4-aminoazobenzene

1989 ◽  
Vol 54 (6) ◽  
pp. 1549-1563 ◽  
Author(s):  
Jiří Barek ◽  
Helena Haladová-Bláhová ◽  
Jiří Zima
Keyword(s):  
Differential Pulse ◽  
Voltammetric Determination ◽  
Differential Pulse Polarography ◽  
Determination Limit ◽  
Polarographic Reduction ◽  
Hanging Mercury Drop Electrode ◽  
Optimal Conditions ◽  
Pulse Polarography ◽  
Mixed Water

The polarographic reduction of 4-haloderivatives of N,N-dimethyl-4-aminoazobenzene has been studied in mixed water-methanol medium, a mechanism has been proposed and optimal conditions have been found for determination of these substances by TAST polarography with a determination limit of about 1.10-6 mol l-1, by differential pulse polarography with a determination limit of about 1.10-7 mol l-1 and linear scan voltammetry with a determination limit of about 5.10-8 mol l-1. In the latter technique, the determined substance was accumulated by adsorption on the surface of a hanging mercury drop electrode to decrease the determination limit below 1.10-8 mol l-1.

The polarographic and voltammetric determination of 2,6-dicyano-4-nitro-2'-acetylamino-4'-diethylaminoazobenzene

1990 ◽  
Vol 55 (6) ◽  
pp. 1508-1517 ◽  
Author(s):  
Jiří Barek ◽  
Dagmar Civišová ◽  
Ashutosh Ghosh ◽  
Jiří Zima
Keyword(s):  
Azo Dye ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Determination Limit ◽  
Polarographic Reduction ◽  
Hanging Mercury Drop Electrode ◽  
Optimal Conditions ◽  
Pulse Polarography ◽  
Pulse Voltammetry

The polarographic reduction of the title azo dye was studied and optimal conditions were found for its analytical utilization in the concentration range 1 . 10-6 - 1 . 10-7 mol l-1 using differential pulse polarography and 1 . 10-6 - 1 . 10-8 mol l-1 using fast scan differential pulse voltammetry or linear scan voltammetry at a hanging mercury drop electrode. When the latter technique is combined with adsorptive accumulation of the studied substance on the surface of the hanging mercury drop, the determination limit can be further decreased to 3 . 10-9 mol l-1.

The polarographic and voltammetric determination of 5-(3-phenoxysulphenylazo)-6-hydroxy-3-cyano-1,4-dimethyl-2-pyridone

1989 ◽  
Vol 54 (8) ◽  
pp. 2105-2119 ◽  
Author(s):  
Jiří Barek ◽  
Ivana Švagrová-Hauserová ◽  
Jiří Zima
Keyword(s):  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Determination Limit ◽  
Polarographic Reduction ◽  
Optimal Conditions ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Layer Chromatography

The polarographic reduction of the title azodye has been studied, a mechanism was proposed and optimal conditions were found for the determination of this substance by TAST polarography in the range 5.10-5-2.10-6 mol l-1 and differential pulse polarography at a dropping mercury electrode in the range 5.10-5-2.10-8 mol l-1. The sensitivity was further increased by adsorptive accumulation of the determined substance on the surface of a hanging mercury drop electrode with linear scan voltammetry (determination limit 5.10-10 mol l-1). The selectivity was increased by prior separation of the determined azodye using thin layer chromatography and by transferring the substance adsorbed on the surface of the hanging mercury drop to a new base electrolyte solution.

The Polarographic and Voltammetric Determination of 1-(3'-Carbamoylphenyl)-3,3-dimethyltriazene

1992 ◽  
Vol 57 (11) ◽  
pp. 2263-2271
Author(s):  
Jiří Barek ◽  
Jana Kubíčková ◽  
Viktor Mejstřík ◽  
Jiří Zima
Keyword(s):  
Differential Pulse Voltammetry ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Test Substance ◽  
Polarographic Reduction ◽  
Hanging Mercury Drop Electrode ◽  
Optimal Conditions ◽  
Pulse Polarography ◽  
Pulse Voltammetry

A study was made of the polarographic reduction of the title triazene, a mechanism was proposed for this process and optimal conditions were found for its analytical application using tast polarography in the range 1 . 10-4 - 2 . 10-6 mol l-1, differential pulse polarography in the range 1 . 10-4 - 2 . 10-7 mol l-1 and fast scan differential pulse voltammetry at a hanging mercury drop electrode in the range 1 . 10-4 - 2 . 10-7 mol l-1. The sensitivity of the latter technique was increased through adsorptive accumulation of the test substance on the surface of the working electrode, permitting determination in the concentration range 1 . 10-7 - 2 . 10-9 mol l-1.

The Polarographic Determination of 1-[4'-(Phenylazo)phenyl]-3,3-dimethyltriazene

1992 ◽  
Vol 57 (11) ◽  
pp. 2248-2262 ◽  
Author(s):  
Jiří Barek ◽  
Dana Dřevínková ◽  
Jiří Zima ◽  
Arnold Fogg
Keyword(s):  
Differential Pulse ◽  
Polarographic Determination ◽  
Differential Pulse Polarography ◽  
Polarographic Reduction ◽  
Optimal Conditions ◽  
Polarographic Behaviour ◽  
Pulse Polarography ◽  
Methanol Medium ◽  
Mixed Water

A study has been made of the polarographic behaviour of genotoxic 1-[4'-(phenylazo)phenyl]-3,3-dimethyltriazene in mixed water-methanol medium. A mechanism has been proposed for its polarographic reduction and optimal conditions have been found for its determination by tast polarography in the concentration range 1 . 10-4 - 2 . 10-6 mol l-1 and using differential pulse polarography in the concentration range 1 . 10-4 - 2 . 10-7 mol l-1.

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.

The polarographic and voltammetric determination of congo red

1987 ◽  
Vol 52 (4) ◽  
pp. 867-877
Author(s):  
Jiří Barek ◽  
Barbara Tietzová ◽  
Jiří Zima
Keyword(s):  
Congo Red ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Polarographic Reduction ◽  
Optimal Conditions ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Pulse Voltammetry

The polarographic reduction of the bisazodye congo red has been studied, a mechanism was proposed for this process and optimal conditions were found for determination of this substance by TAST polarography and differential pulse polarography at a dropping mercury electrode and using fast scan differential pulse voltammetry and voltammetry with linearly increasing voltage at a hanging mercury drop electrode. The detection limit for the latter two techniques is about 10-8 mol l-1; a further decrease in the value can be attained by prior accumulation of the determined substance by adsorption on the surface of the working electrode.

The polarographic and voltammetric determination of the 3'-halogen derivatives of N,N-dimethyl-4-aminoazobenzene

1990 ◽  
Vol 55 (12) ◽  
pp. 2904-2913 ◽  
Author(s):  
Jiří Barek ◽  
Jana Kubíčková ◽  
Viktor Mejstřík ◽  
Oldřich Petira ◽  
Jiří Zima
Keyword(s):  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Polarographic Reduction ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Pulse Voltammetry ◽  
Mixed Water ◽  
Derivatives Of

The polarographic reduction of the 3'-halogen derivatives of N,N-dimethyl-4-aminoazobenzene was studied in mixed water-methanol medium and optimum conditions were found for the determination of these genotoxic substances by tast polarography in the concentration range 1 . 10-4 to 2 . 10-6 mol l-1, differential pulse polarography at a dropping mercury electrode in the range 1 . 10-4 to 2 . 10-7 mol l-1 and fast scan differential pulse voltammetry at a hanging mercury drop electrode in the range 1 . 10-6 to 2 . 10-8 mol l-1. The increase in the sensitivity resulting from adsorptive accumulation of the studied substances on the surface of a hanging mercury drop can be utilized in the determination using the latter method in the concentration range 1 . 10-8 to 2 . 10-9 mol l-1.

The Polarographic and Voltammetric Determination of N,N-Dimethyl-4-amino-3'-nitroazobenzene

1993 ◽  
Vol 58 (2) ◽  
pp. 295-309 ◽  
Author(s):  
Jiří Barek ◽  
Dana Dřevínková ◽  
Viktor Mejstřík ◽  
Jiří Zima
Keyword(s):  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Test Substance ◽  
Polarographic Reduction ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode

The polarographic reduction of N,N-dimethyl-4-amino-3'-nitroazobenzene was studied by tast polarography and differential pulse polarography, constant potential coulometry and cyclic voltammetry and mechanism was proposed for the reduction. Optimal conditions were found for the determination of the test substance using tast polarography in concentration range 1 . 10-4 - 2 . 10-6 mol l-1, differential pulse polarography at classical dropping mercury electrode and fast scan differential pulse voltammetry at a hanging mercury drop electrode in range 1 . 10-4 - 2 . 10-7 mol l-1 and linear scan voltammetry at a hanging mercury drop electrode in range 1 . 10-5 - 2 . 10-8 mol l-1. A further increase in the sensitivity was achieved through adsorptive accumulation of the test substance on the surface of the working electrode, permitting the determination to be carried out in the concentration range 1 . 10-7 - 2 . 10-9 mol l-1.

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 N,N’-dinitrosopiperazine

1991 ◽  
Vol 56 (7) ◽  
pp. 1434-1445 ◽  
Author(s):  
Jiří Barek ◽  
Ivana Švagrová ◽  
Jiří Zima
Keyword(s):  
Mercury Electrode ◽  
Linear Sweep Voltammetry ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Polarographic Reduction ◽  
Concentration Region ◽  
Pulse Polarography ◽  
Chemical Efficiency ◽  
Dropping Mercury Electrode

Polarographic reduction of the genotoxic N,N’-dinitrosopiperazine was studied and its mechanism was suggested. Optimum conditions were established for the determination of this substance by tast polarography over the concentration region of 1 . 10-3 to 1 . 10-6 mol l-1 and by differential pulse polarography on the conventional dropping mercury electrode or by fast scan differential pulse voltammetry and linear sweep voltammetry on a hanging mercury drop electrode over the concentration region of 1 . 10-3 to 1 . 10-7 mol l-1. Attempts at increasing further the sensitivity via adsorptive accumulation of the analyte on the surface of the hanging mercury drop failed. The methods are applicable to the testing of the chemical efficiency of destruction of the title chemical carcinogen based on its oxidation with potassium permanganate in acid solution.

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