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Determination of propyl gallate on carbon paste electrode
Vysoká, Marie ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
Propyl gallate (PG) is a significant synthetic antioxidant and preservative. Its determination has been studied at carbon paste electrode (CPE) using differential pulse voltammetry (DPV) and high performance liquid chromatography with electrochemical detection (HPLC-ED) and with UV spectrometric detection (HPLC-UV). Concentration dependences were measured in the media of Britton-Robinson buffer (pH 5) and methanol (20 %, v/v) by DPV and the limit of detection 0,6110-7 moldm-3 was obtained. Using HPLC with a mobile phase consisting of 0,01 moldm-3 phosphate buffer (pH 4) and methanol (50 %, v/v) with potential of working electrode E = +0,8 V and detection wavelength λ = 280 nm, concentration dependences were measured. Limit of detection was determined to 0,39 moldm-3 for HPLC-ED and 4,95 moldm-3 for HPLC-UV. After verification of the extraction procedure PG was determined in vegetable oil. The resulting value of 3,2 mgkg-1 corresponds with permited limits.
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Carbon - based electrodes: From detection of biologically significant compounds to application in neurodegenerative diseases
Jarošová, Romana ; Zima, Jiří (advisor) ; Vyskočil, Vlastimil (referee) ; Navrátil, Tomáš (referee)
CARBON BASED ELECTRODES: FROM DETECTION OF BIOLOGICALLY SIGNIFICANT COMPOUNDS TO APPLICATION IN NEURODEGENERATIVE DISEASES By Romana Jarošová Carbon is a truly remarkable element that is essential to life on Earth, and its unique properties have made it an indispensable component in an astonishingly diverse array of applications. Whether serving as a fuel source or as a key component in electronic devices, carbon's ability to exist in different forms, each with their distinct physical and chemical properties, contributes to its widespread and continued use. Electrode production is one of the areas where carbon found its significant use. This thesis represents a unique combination of fundamental and applied electrochemistry using carbon-based electrodes. It explores a wide range of topics, from evaluating electrode microstructure as a critical factor affecting its electroanalytical behavior, to the use of carbon- based electrodes in Alzheimer's disease (AD) research. The first part of this Thesis focuses on the electrochemical performance of carbon-based electrodes with distinct microstructures. Specifically, this section discusses two novel electrode materials: boron-doped diamond and nitrogen-incorporated tetrahedral amorphous carbon. The microstructure of each electrode was investigated, and the...
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Voltammetric Determination of DNA Damage Caused by Genotoxic 2-Aminofluorene at a Carbon Film Electrode
Faťarová, Mária ; Vyskočil, Vlastimil (advisor) ; Zima, Jiří (referee)
A large-surface carbon film electrode (ls-CFE) represents a suitable alternative to the commercially available disposable screen-printed carbon working electrodes. Its simple, fast and inexpensive preparation, simple mechanical renewal of the electrode surface (by wiping off the old film with filter paper and forming a new one), good repro- ducibility of measurements, elimination of problems connected with "electrode history" and simple chemical modification are its main advantages. In this Bachelor Thesis, the utilization of ls-CFE for the preparation of a simple elec- trochemical DNA biosensor for the detection of carcinogenic environmental pollutant, 2-aminofluorene (2-AF), is presented. The composition of carbon ink suspension was optimized and tested using a Fe(II)/Fe(III) redox system by cyclic voltammetry (CV). A large-surface solid electrode, covered by a carbon film of the optimum composition, was then used as a transducer for the preparation of double stranded DNA (dsDNA) based electrochemical DNA biosensor (dsDNA/ls-CFE). The electrochemical behavior of dsDNA (i) present in the measured supporting electrolyte (0.1 mol.L−1 acetate buffer of pH 4.7) or (ii) attached at the ls-CFE surface (by covering with dsDNA stock solution and leaving to dry) was investigated using square wave voltammetry...
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Construction of an electrochemical cell based on carbon film electrode
Libánský, Milan ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
This Thesis deals with the construction of an electrochemical cell with two types of integrated composite electrodes based on carbon films. Using these electrodes, the voltammetric behavior of environmental pollutant triclosan (5-chlor-2-(2,4- dichlorophenoxy)phenol) was studied. For the construction of composite electrodes, graphite and glassy carbon were used as conductive microparticles. Several types of polymers served as the nonconductive binder. For the measurements, combinations of graphite with polystyrene and graphite with polycarbonate were selected as optimum materials. From the dependence of peak heights on solution composition, a mixture of a buffer of pH 7 and methanol (1:9, V/V) was selected as the optimum medium. In this medium, concentration dependences were measured; calculated triclosan detection limit were 0,49 µmol dm-3 for carbon polystyrene composite electrode and 0,25 µmol dm-3 for carbon polycarbonate composite electrode, respectively. The possibility of further increasing the sensitivity of the determination by the accumulation step was studied. Accumulation of triclosan on carbon polystyrene composite electrode was observed, but the increase in response was connected with the loss of repeatability. Accumulation of triclosan on carbon polycarbonate composite electrode was...
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Determination of tumor markers using carbon paste electrodes
Adámková, Hana ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
In this master s thesis, electrochemical determination of homovanillic acid (HVA) andˈ vanillylmandelic acid (VMA) was performed on carbon paste electrode. The purpose of this thesis was finding out optimal conditions for determination of these analytes by ndifferential pulse voltammetry (DPV) and high pressure liquid chromatography with a carbon paste electrode as an electrochemical detector (HPLC-ED). The electrochemical behavior of the compounds depends mainly on pH of the solution; the best results are obtained in acidic medium. The limits of detection for DPV method were for HVA 0,38 μmol·dm-3 and for VMA 0,25 μmol·dm-3 . The limits of detection for HPLC-ED were for HVA 0,7 μmol·dm-3 and for VMA 0,2 μmol·dm-3 . Developed method was successfully used for the determination of homovanillic and vanillylmandelic acid in urine samples. With HPLC - ED the limits of detection 0,8 μmol·dm-3 (HVA) and 0,5 μmol·dm-3 (VMA) were achieved. Key words: Homovanillic acid, vanillylmandelic acid, carbon paste electrode, DPV, HPLC
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Determination of phloretine using carbon paste electrode
Fähnrichová, Barbora ; Zima, Jiří (advisor) ; Vyskočil, Vlastimil (referee)
Title: Determination of phloretin using carbon paste electrode Annotation: The aim of this work is the determination of phloretin using differential pulse voltammetry (DPV) and DC voltammetry (DCV). As a working electrode carbon paste electrode was used. Optimal pH conditions for determination using DPV and DCV were found. Under these conditions calibration dependences were measured and limits of detection were calculated. The limit of detection for DPV method was 7,3∙10-7 mol∙l-1 phloretin, for DCV method was 1,0∙10-6 mol∙l-1 phloretin. Further decrease in limit of detection was acchieved by adsorptive stripping differential pulse voltammetry (AdS DPV). The calculated limit of detection was 4,4∙10-7 mol∙l- 1 phloretin using AdS DPV. Key words: Phloretin Carbon paste electrode Differential pulse voltammetry DC (direct current) voltammetry
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