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Voltammetric determination of drugs doxycycline and dimenhydrinate using carbon film electrode
Humpolíková, Jiřina ; Fischer, Jan (advisor) ; Dejmková, Hana (referee)
This bachelor's thesis concerns the determination of doxycycline (DX) and dimenhydrinate (DMH) by the methods DC voltammetry (DCV) and differential pulse voltammetry (DPV) on a carbon film electrode (CFE). The optimum conditions for voltammetric determination of DX and DMH were found and under these conditions, concentration dependences were measured and the limits of quantification (LOQ) were calculated for each method. The media of BR-buffer pH 12.0 was chosen as optimum for DCV and DPV determination of DX at CFE. For both DCV and DPV, the linear concentration dependences were obtained in concentration ranges of DX from 20 µmol·l-1 to 100 µmol·l-1 with LOQ 15,4 µmol·l-1 for DCV and 15,2 µmol·l-1 for DPV. DX was determined in drug using DCV under optimized conditions and for comparison of used voltammetric method DX in drug was determined also using UV-VIS spectrophotometry with consistent results. The optimum medium of BR buffer pH 3.0 was chosen for determination of DMH by DCV and pH 2.0 for DPV. The calibration range 2,0 - 10,0 µmol·l-1 of DMH was received using DCV and 0,2 - 1,0 µmol·l-1 of DMH was recevied using DPV at CFE with reached LOQ 0,08 µmol·l-1 for DCV and 0,02 µmol·l-1 for DPV. DMH was determined in comertional drugs using DCV on founded conditions. The stability of stock solution...
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Voltammetric Determination of Genotoxic 4-Nitroindane at Mercury and Silver Amalgam Electrodes
Burdová, Vendula ; Vyskočil, Vlastimil (advisor) ; Zima, Jiří (referee)
Presented Diploma Thesis is focused on electroanalytical determination of genotoxic 4-nitroindane, one of the nitrated polycyclic aromatic hydrocarbons (NPAHs). A hydrocarbon indane (a component of petrol) is a precursor of 4-nitroindane. NPAHs are produced all above by combustion processes in gasoline and diesel engines. It has been shown that NPAHs can be many times more mutagenic or carcinogenic than their parent PAHs, so the analysis of these dangerous pollutants becomes important for modern environmental analytical chemistry. Optimal conditions for determination of 4-nitroindane have been investigated in buffered water-methanolic solutions and electrochemical transformations of 4-nitroindane have been studied by DC voltammetry (DCV), differential pulse voltammetry (DPV) and cyclic voltammetry at a hanging mercury drop electrode (HMDE) and at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE). For voltammetric determination of 4-nitroindane, the following techniques were used: DCV (limit of quantification (LQ) ~ 7. 10-8 mol. l-1 ), DPV (LQ ~ 1. 10-7 mol. l-1 ) and adsorptive stripping voltammetry (AdSV; LQ ~ 7. 10-9 mol. l-1 ) at HMDE, and DCV (LQ ~ 1. 10-7 mol. l-1 ) and DPV (LQ ~ 1. 10-7 mol l-1 ) at m-AgSAE. The applicability of the newly developed...
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Voltammetric Determination of 4-Nitrobiphenyl at a Mercury Meniscus Modified Silver Solid Amalgam Electrode
Horáková, Eva ; Schwarzová, Karolina (referee) ; Barek, Jiří (advisor)
The presented bachelor thesis is devoted to study of electrochemical behavior of 4-nitrobiphenyl (4-NBP) and to finding of optimum conditions for its' determination using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE). The aim was to achieve the lowest possible limit of determination and to verify the applicability of the newly developed method for determination of 4-NBP in model samples of drinking water. Methanol-acetate buffer pH 4,8 (3:7) was found as an optimum medium for the determination of 4 NBP at a m-AgSAE in deionized water. During DCV it is not necessary to apply electrochemical regeneration of the working electrode, during DPV it is proper to apply following regeneration potentials: Ereg,1 = 0 mV, Ereg,2 = -1300 mV. The concentration dependence of the peak current was found to be linear for both methods for 10-5, 10-6 and 10-7 mol∙l-1 concentration ranges. The limit of determination of 4-NBP both by DCV and by DPV is 2∙10-7 mol∙l-1. The optimum medium for the determination of 4-NBP in drinking water is the mixture of the sample and acetate buffer pH 4,8 in the 9:1 ratio.. During DCV regeneration was not applied, during DPV it was applied with the following regeneration potentials: Ereg,1...
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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...
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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...
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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.
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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.
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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.
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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.
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