Possibility of determination of some derivatives of pterin important in the diagnostics of malignant tumours by using differential pulse polarography

1986 ◽  
Vol 51 (1) ◽  
pp. 34-44
Author(s):  
Václav Kočmíd ◽  
Miroslav Podolák ◽  
Jiří Čoupek ◽  
Oskar Andrýsek
Keyword(s):  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Polarographic Reduction ◽  
Malignant Tumours ◽  
Cathodic Stripping Voltammetry ◽  
Polarographic Behaviour ◽  
Pulse Polarography ◽  
Derivatives Of

The polarographic behaviour of 6,7-dimethylpterin, xanthopterin, 6-pterinaldehyde, neopterin and 6-hydroxymethylpterin was investigated. These compounds are suitably determined by employing differential pulse polarography; some results suggest the possibility of their determination by cathodic stripping voltammetry with adsorptive accumulation. For all compounds, the effect of pH on polarographic reduction was examined. Under optimal conditions, the calibration curve of all compounds under investigation was linear in the range 2 . 10-6 - 1 . 10-7 mol/l and the detection limit was below 1 . 10-7 mol/l.

Determination of Arsenic and Selenium in Foods By Electroanalytical Techniques

1976 ◽  
Vol 59 (3) ◽  
pp. 650-654 ◽  
Author(s):  
Walter Holak
Keyword(s):  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Magnesium Nitrate ◽  
Differential Pulse Polarography ◽  
Cathodic Stripping Voltammetry ◽  
Pulse Polarography ◽  
Trivalent State ◽  
Relative Standard ◽  
Cathodic Stripping

Abstract Arsenic and selenium are determined in foods by differential pulse polarography and cathodic stripping voltammetry. The sample is digested with nitric acid and magnesium nitrate and then dissolved in dilute hydrochloric acid. An aliquot is removed, the arsenic is chemically reduced to the trivalent state, and interferences are removed by ion exchange before polarography. Selenium is determined in a second aliquot by cathodic stripping voltammetry. Recoveries for both elements in several foods were from 90 to 110%. The relative standard deviations for arsenic at 5 ppm and selenium at 0.48 ppm were 5.8 and 7.3%, respectively.

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.

Polarographic and Voltammetric Determination of 7-[4-Methyl-5-phenyl-2-(1,2,3-triazolyl)]-3-phenylcoumarin

1994 ◽  
Vol 59 (2) ◽  
pp. 309-321
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř
Keyword(s):  
Direct Determination ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Whitening Agent ◽  
Polarographic Behaviour ◽  
Pulse Polarography ◽  
Pulse Voltammetry ◽  
Adsorption Stripping Voltammetry

The polarographic behaviour of the optical whitening agent 7-[4-methyl-5-phenyl-2-(1,2,3-triazolyl)]-3-phenylcoumarin was studied in mixed aqueous-methanolic solutions. Conditions were found for quantitating the substance by tast polarography, differential pulse polarography, differential pulse voltammetry at a hanging mercury drop electrode, and adsorption stripping voltammetry over the concentration regions of 2 - 10, 0.1 - 10, 0.02 - 1 and 0.004 - 1 μmol l-1, respectively. The methods developed were applied to a direct determination of the substance in a technological product.

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.

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.

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.

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.

Polarographic Determination of 6-β-D-Glucopyranosyloxy-7-hydroxycoumarin

1996 ◽  
Vol 61 (3) ◽  
pp. 333-341
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř ◽  
Josino C. Moreira ◽  
Jiří Zima
Keyword(s):  
Natural Compound ◽  
Mercury Electrode ◽  
Direct Determination ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Whitening Agent ◽  
Polarographic Behaviour ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode

The polarographic behaviour was studied for 6-β-D-glucopyranosyloxy-7-hydroxycoumarin, a natural compound serving as an optical whitening agent. The substance can be quantitated by tast polarography, differential pulse polarography using a conventional dropping mercury electrode, and differential pulse polarography using a static mercury drop electrode over the regions of 20-1 000, 2-1 000, and 0.2-1 000 μmol l-1, respectively. The methods developed for the quantitation of the compound were applied to its direct determination in a raw product.

Polarographic and Voltammetric Determination of Trace Amounts of 3-Nitrofluoranthene

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1571-1587 ◽  
Author(s):  
Karel Čížek ◽  
Jiří Barek ◽  
Jiří Zima
Keyword(s):  
River Water ◽  
Solid Phase ◽  
Mercury Electrode ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Pulse Polarography ◽  
Dropping Mercury Electrode ◽  
Separation And Preconcentration

The polarographic behavior of 3-nitrofluoranthene was investigated by DC tast polarography (DCTP) and differential pulse polarography (DPP), both at a dropping mercury electrode, differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV), both at a hanging mercury drop electrode. Optimum conditions have been found for its determination by the given methods in the concentration ranges of 1 × 10-6-1 × 10-4 mol l-1 (DCTP), 1 × 10-7-1 × 10-4 mol l-1 (DPP), 1 × 10-8-1 × 10-6 mol l-1 (DPV) and 1 × 10-9-1 × 10-7 mol l-1 (AdSV), respectively. Practical applicability of these techniques was demonstrated on the determination of 3-nitrofluoranthene in drinking and river water after its preliminary separation and preconcentration using liquid-liquid and solid phase extraction with the limits of determination 4 × 10-10 mol l-1 (drinking water) and 2 × 10-9 mol l-1 (river water).

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