|
|
Voltammetric Determination of Flutamide at Screen-Printed Carbon Electrodes
Škvarla, Juraj ; Fischer, Jan (referee) ; Vyskočil, Vlastimil (advisor)
The paper deals with the electrochemical behaviour of flutamide at screen-printed carbon electrodes (SPCE) with the aim of optimizing conditions for their practical use in the in situ analyses. A stability of stock solution was verified and confirmed primarily. Then, an influence of pH, stirring time and flutamide concentration in the analyzed solution on the voltammetric behavior of flutamide were systematically studied using DC voltammetry and differential pulse voltammetry at SPCE. One well-developed voltammetric peak of flutamide was detected in the whole pH region investigated. The time of stirring appears to be of crucial importance for the result of measurements at all pHs. The longer time of stirring of the solution prior to measurements, the higher is the flutamide peak. Therefore, the time of stirring was set constant for the rest of measurements. The optimum conditions for voltammetric determination have been found in Britton-Robinson buffer pH 7.0 - methanol (9:1) for both DCV and DPV at SPCE. Concentration dependences were found to be linear for the range 1·10-6 - 1·10-4 mol·dm-3 and evaluable (but not reliable) up to 1·10-7 mol·dm-3 . Reached limits of quantification were 6·10-7 mol·dm-3 for DCV at SPCE and 8·10-7 mol·dm-3 for DPV at SPCE. The determination of flutamide in...
|
|
|
Voltammetric Determination of Metronidazol at a Polished Silver Solid Amalgam Composite Electrode
Škvorová, Lucie ; Zima, Jiří (referee) ; Barek, Jiří (advisor)
The aim of this work was to find out the optimal conditions for voltammetric determination of metronidazole, which is used as an anti-tumor drug. The stability of stock solution of metronidazole in deionized water was monitored using UV-VIS absorption spectrophotometry. Optimum conditions for voltammetric determination of metronidazole at a polished silver solid amalgam composite electrode (p-AgSA-CE) have been investigated. The dependence of voltammetric behavior of metronidazole (1∙10-4 mol/L) on pH of analyzed solution has been investigated using DC voltammetry (DCV) and differential pulse voltammetry (DPV) in the pH range 2,1 - 12,1 in aqueous media of Britton- Robinson (BR) buffer. For electrochemically reducible nitro group of metronidazole, the mechanism of voltammetric reduction at p-AgSA-CE was proposed. The optimum medium of aqueous BR buffer pH 4.0 was chosen for measuring the concentration dependences for both voltammetric techniques. The concentration range 2∙10-6 - 1∙10-4 mol/L of metronidazole was measured using DCV and DPV at p-AgSA-CE with reached limits of quantification (LQs) 2∙10-6 mol/L and 4∙10-6 mol/L for DCV and DPV, respectively. For comparison of used voltammetric techniques with supplemental analytical method, the concentration range 2∙10-6 - 1∙10-4 mol/L of metronidazole...
|
|
|
Determination of propyl gallate on carbon paste electrode
Vysoká, Marie ; Fischer, Jan (referee) ; Zima, Jiří (advisor)
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.
|
|
|
Spray-coated working electrodes of electrochemical sensors
Lechner, Filip ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This thesis is about the selection of the better type of thick film working electrode for the detection of substances in aqueous solutions, modified by spray coated carbon nanotubes. The theoretical part of this thesis describes the technology of thick film, properties and production of carbon nanotubes, introduction to electrochemistry and electroanalytical methods for the detection of substances in aqueous solutions. The practical part is aimed to realization of the working electrodes by thick film technology and their modification by spray-coated layer consist of carbon nanotubes. Electrodes are characterized using voltammetric methods, electrochemical impedance spectroscopy and electron microscopy. In conclusions is selected the most suitable type of working electrodes for reproducible electrochemical analysis.
|
|
|
Study of DNA-doxorubicine interaction by electrochemical methods on nanostructured electrodes
Přibyl, Jakub ; Fohlerová, Zdenka (referee) ; Kynclová, Hana (advisor)
Cancer diseases are one of the leading causes of mortality worldwide, for this reason, great attention anticancer drugs. Doxorubicin falls into the category of the most widely used cancer drugs. The method of electrochemical impedance spectroscopy were investigated properties of golds electrodes without deposit nanoparticles and electrodes with deposit gold nanoparticles. Using voltammetric measurements we detected doxorubicin and investigated the interaction of doxorubicin with oligonucleotides on gold electrodes without nanoparticles and electrodes modified with gold nanoparticles.
|
|
| |
|
|
Thick-film sensors for heavy metals detection
Gajdoš, Libor ; Majzlíková, Petra (referee) ; Prášek, Jan (advisor)
This project describes the possibilities of heavy metals detections in solutions using differential pulse voltammetry with tree-electrode electrochemical thick-film sensors. In the theoretical part, the thick-film technology is described as well as thick-film pastes’ types and compositions, followed by introduction to electrochemistry and electro-analytical methods of measurement. This project also describes the three measured heavy metals – cadmium, lead and copper. In the practical part, heavy metals’ ions detection in solutions using carbon working electrode and determination of the detection limit and sensitivity are described and discussed. Finally the evaluation of obtained results and results comparison to hygienic limits are included.
|
|
|
Electrode system of thick-film electrochemical sensors optimization
Gablech, Imrich ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This thesis is about optimization of three-electrode electrochemical sensor for detection of substances in solutions fabricated using standard thick film technology. The theoretical part of this thesis describes the thick film technology, introduction to electrochemistry and electro analytical methods for the detection of substances in solutions. The surface optimization of reference and auxiliary electrode of a three-electrode system is solved in the practical part. In conclusions results of the evaluation and description of the ideal three-electrode system are discussed.
|
|
|
Preparation and characterisation of ceramic electroactive materials for Na-ion batteries
Vaněk, Martin ; Libich, Jiří (referee) ; Čech, Ondřej (advisor)
Hlavním cílem této práce je charakterizace vzorků titanátů, jako materiálů pro sodíko-iontové (Na-ion) akumulátory. Syntéza některých vzorků je součástí této práce. Charakterizace je zaměřena na elektrochemické vlastnosti, složení a morfologii použitých materiálů. První část se zabývá lithium-iontovými (Li-ion) akumulátory. Byly vybrány, protože jsou ve vědeckých článcích dobře popsány a základní funkční princip je aplikovatelný také na Na-ion akumulátory. Materiály používáné pro katody, anody a elektrolyty následují po krátké části shrnující parametry a konstrukci Li-ion akumulátorů. Následující kapitola je zaměřena na sodíko-iontové akumulátory. Srovnání sodíku a lithia je následováno materiály používanými pro elektrody a elektrolyty (s důrazem na anodové materiály). Třetí část popisuje analytické metody použité pro charakterizaci elektrod a materiálů. Jedná se o elektrochemickou charakterizaci (cyklická voltametrie a galvanostatické cyklování s potenciálovým omezením), morfologii (rastrovací elektronová mikroskopie) a složení (X-ray difrakční spektroskopie). Poslední dvě kapitoly obsahují syntézu a charakterizaci sodného titanátu a charakterizaci dvou vzorků TiO2. Výsledky této práce jsou shrnuty v závěru.
|
|
|
Thick-film sensors for electrochemical detection of species in aqueous solutions
Martynek, Daniel ; Adámek, Martin (referee) ; Prášek, Jan (advisor)
This work deals with the theory, principles and characteristics of electrochemical sensors, thick-film technology and electrodes used in electrochemistry. Methods for the detection of substances matters in solutions are discussed here. Main emphasis is given to differential pulse voltammetry and the influence of the method setup parameters to the measurement results. Experimentally, the work deals with the modification of thick-film working electrode with carbon nanotubes and subsequent activation of the electrode by nitric acid to increase the detection limit and the current response to selected heavy metals ions. Finally, the obtained results are compared with special commercial paste and discussed with the data state in literature.
|
guest ::
