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Contribution to the use of new types of carbon paste and fiber electrodes for voltammetric and amperometric determination of 5-amino-6-nitroquinoline and resveratrol
Němcová, Lenka ; Zima, Jiří (advisor) ; Vytřas, Karel (referee) ; Navrátil, Tomáš (referee)
7 ABSTRACT (EN) This dissertation thesis is focused on the study of electrochemical properties of new types of carbon paste electrodes (CPE) and carbon fiber rod electrodes (CFRE), which were used for the development of new highly sensitive and selective voltammetric and amperometric methods for the determination of 5-amino-6-nitroquinoline and trans- and cis- isomers of resveratrol. The carbon paste electrodes were compared in terms of size of the microparticles of glassy carbon contained in the paste (diameters 0.4 - 12 µm; 10 - 20 µm; 20 - 50 µm) in comparison with carbon paste electrode consisting of crystalline graphite and solid glassy carbon electrode. The electrochemical properties were tested using potassium hexacyanoferrate in an aqueous supporting electrolyte and 5-amino-6-nitroquinoline (5A6NQ) in a mixed methanol-water supporting electrolyte. The carbon paste electrode was further used in an amperometric detector of a wall-jet type connected in series with a spectrophotometric detector for the development of a new HPLC method with electrochemical detection and spectrophotometric detection for the determination of trans-resveratrol and cis-resveratrol in samples of grains, hulls and leaves of common and tartary buckwheat. The method was optimized and used for the determination of resveratrol in...
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Contribution to the use of new types of carbon paste and fiber electrodes for voltammetric and amperometric determination of 5-amino-6-nitroquinoline and resveratrol
Němcová, Lenka ; Zima, Jiří (advisor) ; Vytřas, Karel (referee) ; Navrátil, Tomáš (referee)
7 ABSTRACT (EN) This dissertation thesis is focused on the study of electrochemical properties of new types of carbon paste electrodes (CPE) and carbon fiber rod electrodes (CFRE), which were used for the development of new highly sensitive and selective voltammetric and amperometric methods for the determination of 5-amino-6-nitroquinoline and trans- and cis- isomers of resveratrol. The carbon paste electrodes were compared in terms of size of the microparticles of glassy carbon contained in the paste (diameters 0.4 - 12 µm; 10 - 20 µm; 20 - 50 µm) in comparison with carbon paste electrode consisting of crystalline graphite and solid glassy carbon electrode. The electrochemical properties were tested using potassium hexacyanoferrate in an aqueous supporting electrolyte and 5-amino-6-nitroquinoline (5A6NQ) in a mixed methanol-water supporting electrolyte. The carbon paste electrode was further used in an amperometric detector of a wall-jet type connected in series with a spectrophotometric detector for the development of a new HPLC method with electrochemical detection and spectrophotometric detection for the determination of trans-resveratrol and cis-resveratrol in samples of grains, hulls and leaves of common and tartary buckwheat. The method was optimized and used for the determination of resveratrol in...
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Determination of arbutin using carbon paste electrode
Libánský, Milan ; Zima, Jiří (advisor) ; Navrátil, Tomáš (referee)
This bachelor thesis concerns to the optimization of the conditions for the determination of hydroquinone-β-D-glucopyranoside (arbutin) by the differential pulse voltammetry on carbon paste electrode. From the dependence of peak heights on the pH, buffer of pH 2 was selected as the optimum medium. In this media, concentration dependences were measured and detection limit and quantification limit of 0.73×10-6 mol/l and 2.42×10-6 mol/l, respectively, were obtained. The possibility of further increase of the sensitivity of determination by the accumulation step was studied, but the accumulation of arbutin was not observed even after ten minutes. The developed method for the determination of arbutin was verified by its determination in the real sample of the cosmetic cream. Results of extraction of arbutin to methanolic and aqueous solution were studied. Concentration of the analyte was determined by standard addition method. In the case of methanolic solution, very good repeatability of the measurements and agreement of the determined and declared content of arbutin in the cream was found. In the aqueous solution much lower amount of arbutin was found, probably due to incomplete extraction of the analyte.
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Determination of sulfamethizole using carbon paste electrodes
Mikeš, Miroslav ; Zima, Jiří (advisor) ; Vyskočil, Vlastimil (referee)
The proposed Thesis deals with the electrochemical behavior of sulfamethizole on carbon paste electrodes. Sulfamethizole is a sulfonamide antibiotic effective against a number of gram-positive and gram-negative bacteria. In human medicine, the most frequent application is for the treatment of urinary tract. In veterinary medicine, it is used for the and preventive treatment of both aquatic and terrestic animals. Due to the wide utilization and low metabolization, it also presents an environmental burden. The development of quick and sensitive methods for the determination in both biological and pharmaceutical matrices is therefore important. This Thesis deals with the search of optimum conditions for differential pulse voltammetric determination of sulfamethizole in tablets Micturol sedante, used for the treatment of urinary tract. The method uses Britton-Robinson (B-R) buffer pH 7 and reaches detection limit 0,39 µmol·l-1 . Results of the method complied with the manufacturer's information and with the results of spectrophotometric determination. In the other part of the work, conditions for the determination of sulfamethizole determination in urine samples. Fonund conditions were: Lichrospher® RP-18, 100 (5 µm), 125×4 mm, (LichroCART) column, mobile phase B-R buffer pH 3 : methanol (7:3, v/v) and...
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