Polarographic determination of azobenzene

1986 ◽  
Vol 51 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř
Keyword(s):  
Detection Limit ◽  
Electrode Surface ◽  
Linear Sweep Voltammetry ◽  
Polarographic Determination ◽  
Hanging Mercury Drop Electrode ◽  
Linear Sweep ◽  
Aqueous Methanol ◽  
Mercury Drop Electrode

Conditions were found for the determination of azobenzene by means of DC, AC, TAST, DP, and FSDP polarography and linear sweep voltammetry on a hanging mercury drop electrode in the medium of aqueous methanol, which ensures a sufficient solubility of azobenzene. In the latter two methods, the detection limit was around 10-8 mol/l; a still lower value could be attained by preliminary accumulation of azobenzene, i.e. adsorption on the electrode surface.

Polarographic and voltammetric determination of N,N-dimethyl-4-aminoazobenzene

1986 ◽  
Vol 51 (10) ◽  
pp. 2083-2090 ◽  
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř
Keyword(s):  
Linear Sweep Voltammetry ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Hanging Mercury Drop Electrode ◽  
Chemical Carcinogen ◽  
Linear Sweep ◽  
Pulse Polarography ◽  
Pulse Voltammetry ◽  
Methanolic Medium

Conditions were found for the determination of chemical carcinogen N,N-dimethyl-4-aminoazobenzene by TAST and differential pulse polarography, fast scan differential pulse voltammetry and linear sweep voltammetry at a hanging mercury drop electrode in a mixed aqueous-methanolic medium. The detection limit of the last two methods, approximately 10-8 mol l-1, can be further lowered by preliminary accumulation of the substance to be determined by adsorption at a working electrode. The applicability of these methods to the analysis of biological materials, directly or combined with an extraction, was demonstrated.

Polarographic and Voltammetric Determination of 4,4'-Bis[(4-phenylamino-6-morpholino-1,3,5-triazin-2-yl)amino]stilbene-2,2'-disulfonic Acid

1995 ◽  
Vol 60 (8) ◽  
pp. 1247-1260
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř ◽  
Josino C. Moreira ◽  
Jiří Zima
Keyword(s):  
Linear Sweep Voltammetry ◽  
Differential Pulse ◽  
Disulfonic Acid ◽  
Differential Pulse Polarography ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Pulse Polarography ◽  
Technical Products ◽  
Layer Chromatography

The polarographic and voltammetric behaviour of the title compound, which is the basic component in many commercial optical whitening agents, was investigated. The optimum conditions were found for the determination of the substance in dimethylformamide solutions containing 5% (v/v) water by tast polarography, differential pulse polarography, linear sweep voltammetry using a hanging mercury drop electrode, and differential pulse polarography using a hanging mercury drop electrode over the concentration regions of 100-500, 10-500, 10-500, and 1-100 mmol l-1, respectively. Practical applicability of the newly developed methods to the determination of the analyte in technical products, either direct or following separation by thin layer chromatography, was verified.

Polarographic and Voltammetric Determination of 4,4'-Bis[(4-phenylamino-6-methoxy-1,3,5-triazin-2-yl)amino]stilbene-2,2'-disulfonic Acid

1994 ◽  
Vol 59 (5) ◽  
pp. 1018-1029 ◽  
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř
Keyword(s):  
Title Compound ◽  
Supporting Electrolyte ◽  
Linear Sweep Voltammetry ◽  
Differential Pulse ◽  
Disulfonic Acid ◽  
Differential Pulse Polarography ◽  
Hanging Mercury Drop Electrode ◽  
Tetraethylammonium Bromide ◽  
Mercury Drop Electrode

The polarographic and voltammetric behaviour was examined for the title compound, which is the basic component in many commercial optical whitening agents. Dimethylformamide containing 5 vol.% water was chosen as the solvent and tetraethylammonium bromide as the supporting electrolyte. The optimum conditions were found for determining the substance by tast polarography, differential pulse polarography, linear sweep voltammetry on a hanging mercury drop electrode, and differential pulse voltammetry on a hanging mercury drop electrode. The analyte concentration regions for the four techniques were 0.1 - 0.5, 0.01 - 0.5, 0.01 - 0.5 and 0.01 - 0.1 mmol l-1, respectively. Practical applicability of the methods to the determination of the title compound in technical products was verified.

The polarographic and voltammetric determination of 2-amino-5-sulphoamoylnaphthalene-azo-(2’-chloro-4’-nitrobenzene)

1988 ◽  
Vol 53 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Jiří Barek ◽  
Jana Balsiene ◽  
Antonín Berka ◽  
Ivana Hauserová ◽  
Jiří Zima
Keyword(s):  
Detection Limit ◽  
Differential Pulse Voltammetry ◽  
Differential Pulse ◽  
Linear Potential ◽  
Polarographic Reduction ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Pulse Voltammetry ◽  
Layer Chromatography

The polarographic reduction of the title azo dye was studied, a mechanism was suggested and optimal conditions were determined for analytical utilization of this process. A detection limit of 3 . 10-7 mol 1-1 was obtained using fast scan differential pulse voltammetry and 0.7 . 10-7 mol 1-1 using linear potential scan voltammetry at a hanging mercury drop electrode. The detection limit can be decreased by adsorptive accumulation of the determined substance on the surface of the hanging mercury drop electrode, to 1 . 10-8 mol 1-1 for fast scan differential pulse voltammetry and 0.6 . 10-8 mol 1-1 for linear scan voltammetry. The selectivity of the determination can be improved by preliminary separation by extraction or thin-layer chromatography.

Polarographic and Voltammetric Determination of 4,4'-Bis[(4-diethanolamino-6-(2,5-disulfophenylamino)-1,3,5-triazin-2-yl)amino]stilbene-2,2'-disulfonic Acid

1996 ◽  
Vol 61 (5) ◽  
pp. 663-672
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř ◽  
Josino C. Moreira ◽  
Jiří Zima
Keyword(s):  
Linear Sweep Voltammetry ◽  
Differential Pulse ◽  
Disulfonic Acid ◽  
Differential Pulse Polarography ◽  
Hanging Mercury Drop Electrode ◽  
Tetraethylammonium Bromide ◽  
Mercury Drop Electrode ◽  
Pulse Polarography ◽  
Technical Products

The polarographic and voltammetric behaviour was studied for 4,4'-bis[(4-diethanolamino-6-(2,5-disulfophenylamino)-1,3,5-triazin-2-yl)amino]stilbene-2,2'-disulfonic acid, which is the basis of many commercial optical whitening agents. The optimum conditions were found for quantitation of this substance in tetraethylammonium bromide solutions in dimethylformamide containing 5% (v/v) water using TAST polarography, differential pulse polarography, linear sweep voltammetry at a hanging mercury drop electrode, and differential pulse voltammetry at a hanging mercury drop electrode over the concentration regions of 100-500, 10-500, 10-500, and 1-100 mmol l-1, respectively. The practical applicability of the new analytical methods to the determination of the substance in technical products was verified.

The polarographic and voltammetric determination of trypane blue

1988 ◽  
Vol 53 (5) ◽  
pp. 921-928
Author(s):  
Jiří Barek ◽  
Janina Balsiene ◽  
Barbara Tietzová ◽  
Jiří Zima
Keyword(s):  
Detection Limit ◽  
Mercury Electrode ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Pulse Voltammetry

The reduction of mutagenic bisazodye trypane blue has been studied at a mercury electrode, a mechanism has been proposed and optimal conditions found for its analytical application. The use of a dropping mercury electrode with a renewable surface yielded a detection limit of 8 . 10-7 mol l-1 for TAST polarography, and 8 . 10-8 mol l-1 for differential pulse polarography; the use of a hanging mercury drop electrode with an unrenewed surface during the measurement yielded detection limit of 6 . 10-8 mol l-1 for fast scan differential pulse voltammetry and 4 . 10-8 mol l-1 for linear scan voltammetry. Preliminary adsorptive accumulation of the determined substance on the surface of the hanging mercury drop electrode led to a decrease in the detection limit to 5 . 10-9 mol l-1 for linear scan voltammetry.

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 voltammetric determination of 4-nitrobiphenyl

1991 ◽  
Vol 56 (3) ◽  
pp. 595-601 ◽  
Author(s):  
Jiří Barek ◽  
Gulamustafa Malik ◽  
Jiří Zima
Keyword(s):  
Differential Pulse Voltammetry ◽  
Differential Pulse ◽  
Voltammetric Determination ◽  
Hanging Mercury Drop Electrode ◽  
Optimum Conditions ◽  
Mercury Drop Electrode ◽  
Working Electrode ◽  
Pulse Voltammetry ◽  
Unstirred Solution

Optimum conditions were found for the determination of 4-nitrobiphenyl by fast scan differential pulse voltammetry at a hanging mercury drop electrode in the concentration range 1 . 10-5 to 2 . 10-7 mol l-1. A further increase in sensitivity was attained by adsorptive accumulation of this substance on the surface of the working electrode, permitting determination in the concentration range (2 – 10) . 10-8 mol l-1 with one minute accumulation of the substance in unstirred solution or (2 – 10) . 10-9 mol l-1 with three-minute accumulation in stirred solution. Linear scan voltammetry can be used to determine 4-nitrobiphenyl in the concentration range (2 – 10) . 10-9 mol l-1 with five-minute accumulation in stirred solution, with the advantage of a smoother baseline and smaller interference from substances that yield only tensametric peaks.

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