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Voltammetric Determination of Nimesulide Using Graphite Composite Electrode
Hubáčková, Monika ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
This Diploma Thesis deals with the study of the electrochemical behaviour of the nonsteroidal anti-inflammatory drug nimesulide. The aim of this work is to find optimal conditions for the determination of nimesulide using voltammetric techniques direct current voltammetry (DCV) and differential pulse voltammetry (DPV) in oxidation and reduction potential regions. An ultra-trace graphite electrode (UTGE) was used as the working electrode. The pH dependence was measured to select the optimal pH, the probable mechanism of reactions was determined, the repeatability of the measurements was checked, and finally the calibration dependences were constructed and evaluated in the selected media. BR buffer media of pH 2 and 4 for DCV and pH 2 and 5 for DPV were selected to measure calibration curves in the concentration range of 0.1-100 µmol L−1 . The detection limits for both methods DCV and DPV at the UTGE were in order of about 10−7 mol L−1 , which are values corresponding to alternative voltametric methods that also use unmodified working electrodes.
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Development of Novel Electrochemical Methods Using Various Membrane Materials for Monitoring of Selected Anticancer Drugs and Phytochelatins
Skalová, Štěpánka
Present Ph.D. Thesis is focused on the development of electrochemical methods for determination of anticancer drugs using various types of membranes for their preliminary separation. Furthermore, this Thesis reports the study of transport mechanisms of heavy metals in the presence of phytochelatins across biological membranes. Sodium anthraquinone-2-sulphonate (AQS) was used as a model compound for its similar structure with anthraquinone-based (AQ-based) anticancer drugs (doxo/daunorubicin) and also due to its better availability. All these compounds can be easily electrochemically oxidized and/or reduced. Redox behaviour of AQS was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in a cathodic region on mercury meniscus modified (m-AgSAE) and polished silver solid amalgam (p-AgSAE) electrodes, Obtained results were used for the development of a micro-volume voltammetric cell (MVVC). Its applicability for voltammetric determination of anticancer drugs was verified by using doxorubicin (DX) as a model substance. The second part of this Thesis deals with therapeutic monitoring of anticancer drugs in the blood circulation of the patients. For pilot experiments, a liquid-flow system with dialysis catheter and amperometric detection was used. The flow rate of carrier...
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Development of Novel Electrochemical Methods Using Various Membrane Materials for Monitoring of Selected Anticancer Drugs and Phytochelatins
Skalová, Štěpánka
Present Ph.D. Thesis is focused on the development of electrochemical methods for determination of anticancer drugs using various types of membranes for their preliminary separation. Furthermore, this Thesis reports the study of transport mechanisms of heavy metals in the presence of phytochelatins across biological membranes. Sodium anthraquinone-2-sulphonate (AQS) was used as a model compound for its similar structure with anthraquinone-based (AQ-based) anticancer drugs (doxo/daunorubicin) and also due to its better availability. All these compounds can be easily electrochemically oxidized and/or reduced. Redox behaviour of AQS was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in a cathodic region on mercury meniscus modified (m-AgSAE) and polished silver solid amalgam (p-AgSAE) electrodes, Obtained results were used for the development of a micro-volume voltammetric cell (MVVC). Its applicability for voltammetric determination of anticancer drugs was verified by using doxorubicin (DX) as a model substance. The second part of this Thesis deals with therapeutic monitoring of anticancer drugs in the blood circulation of the patients. For pilot experiments, a liquid-flow system with dialysis catheter and amperometric detection was used. The flow rate of carrier...
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Voltammetric and amperometric determination of homovanillic, vanillylmandelic, and 5-hydroxyindole-3-acetic acid
Němečková, Anna ; Barek, Jiří (advisor) ; Labuda, Ján (referee) ; Skopalová, Jana (referee)
Presented dissertation thesis is focused on the development of electrochemical methods for the determination of three important tumour biomarkers, namely homovanillic acid (HVA), vanillylmandelic acid (VMA), and 5-hydroxyindole-3-acetic acid (5-HIAA). First part of the study is focused on electrochemical behaviour of these analytes in batch arrangement using differential pulse voltammetry (DPV) at screen-printed carbon electrodes (SPCEs). It has been proved that presented method is sufficiently sensitive for monitoring above mentioned analytes. Moreover, it can be used for determination of HVA and VMA in mixture. Obtained limits of detection (LODs) were 0.24 µmol·L-1 for HVA, 0.06 µmol·L-1 for VMA, and 0.12 µmol·L-1 for 5-HIAA. The requirements to speed up the analysis and at the same time to reduce its price initialized our study of the determination of tested biomarkers in flow systems. Firstly, flow injection analysis with amperometric detection was investigated for the determination of all three biomarkers at the same SPCE, and then an analogous determination of structural more similar pair, HVA and VMA, was performed at a boron doped diamond electrode (BDDE). Obtained LODs of optimized methods were as follows: at SPCE 0.07 µmol·L-1 for HVA, 0.05 µmol·L-1 for VMA, and 0.03 µmol·L-1 for 5-HIAA,...
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Development of Novel Electrochemical Methods Using Various Membrane Materials for Monitoring of Selected Anticancer Drugs and Phytochelatins
Skalová, Štěpánka ; Barek, Jiří (advisor) ; Labuda, Ján (referee) ; Trnková, Libuše (referee)
Present Ph.D. Thesis is focused on the development of electrochemical methods for determination of anticancer drugs using various types of membranes for their preliminary separation. Furthermore, this Thesis reports the study of transport mechanisms of heavy metals in the presence of phytochelatins across biological membranes. Sodium anthraquinone-2-sulphonate (AQS) was used as a model compound for its similar structure with anthraquinone-based (AQ-based) anticancer drugs (doxo/daunorubicin) and also due to its better availability. All these compounds can be easily electrochemically oxidized and/or reduced. Redox behaviour of AQS was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in a cathodic region on mercury meniscus modified (m-AgSAE) and polished silver solid amalgam (p-AgSAE) electrodes, Obtained results were used for the development of a micro-volume voltammetric cell (MVVC). Its applicability for voltammetric determination of anticancer drugs was verified by using doxorubicin (DX) as a model substance. The second part of this Thesis deals with therapeutic monitoring of anticancer drugs in the blood circulation of the patients. For pilot experiments, a liquid-flow system with dialysis catheter and amperometric detection was used. The flow rate of carrier...
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Voltammetric Detection of Purine Nucleobases on Screen-Printed Graphite Electrodes Modified by Nanocarbon Materials
Hasoň, Stanislav ; Ostatná, Veronika ; Fojta, Miroslav
Recent studies have shown that the electrochemical oxidation of purine nucleobases (adenine and geaoine) at graphite electrodes is strongly dependent on the orientation of graphene sheets. their size and mutual distribution on the electrode surface. Edges and defects of graphene sheets affect the kinetics of oxidation processes, basal planes support the adsorption processes The aim of this study is to determine how model carbon nanomaterials including graphene, single-walled or multi-wailed carbon nanotubes. carbon nanofibres and mesoporous graphene affect the electrochemical oxidation or purine nuclebases on screen-printed carbon electrodes modified by these nanostructures in solution without and in the presence of copper.
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Voltammetric and Amperometric Determination of Nitrophenols Using Boron-Doped Diamond Film Electrode
Karaová, Jana ; Barek, Jiří (advisor) ; Šelešovská, Renáta (referee) ; Jaklová Dytrtová, Jana (referee)
Presented Ph.D. Thesis is focused on the use of the boron-doped diamond (BDD) electrodes for voltammetric and amperometric determination of selected nitrophenols: 2-nitrophenol (2NP), 4-nitrophenol (4NP), and 2,4-dinitrophenol (2,4DNP). These compounds are listed as "priority pollutants" by United States Environmental Protection Agency (US EPA) due to their negative impact on living organisms and are mainly used in agriculture as plant growth stimulators. BDD electrodes are used for determination of wide range of electrochemically both reducible and oxidisable organic compounds and have become a popular electrode material thanks to its commercial availability and excellent mechanical and electrochemical properties. A differential pulse voltammetric method was developed for the determination of 2NP, 4NP and 2,4DNP at a BDD film electrode using electrochemical reduction and of 4NP and 2,4DNP using electrochemical oxidation. The method was successfully applied for the direct determination of these compounds in drinking and river water in the concentration range from 4×10-7 to 2×10-5 mol.L-1 . To improve the limit of quantification, a preconcentration by solid phase extraction from 100 mL (drinking and river water) and 1000 mL (drinking water) of water samples was used with limit of determination...
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Electrochemical Investigation of Novel Redox Indicatiors for Detection of DNA Damage
Otépka, Tomáš ; Vyskočil, Vlastimil (advisor) ; Fischer, Jan (referee)
Cílem této práce bylo zkoumání nových redoxních systémů, které by bylo možné využít pro detekci poškození DNA na rtuťovým meniskem modifikované stříbrné pevné amalgámové elektrodě (m-AgSAE). Jako slibné se nabízely komplexy 1,10-fenantrolinu (phen) a iontů přechodných kovů. Konkrétně byly provedeny pokusy s komplexy kobaltaných iontů a phen, jejichž příprava byla provedena slitím roztoků obou složek v příslušném poměru. Chování komplexů v této směsi bylo porovnáno se syntetizovaným komplexním kationtem [Co(phen)3]3+ , a to jednak s využitím voltametrické techniky, jednak spektrofotometricky pomocí UV/VIS spektrofotometrie. Analýzy na m-AgSAE probíhaly s využitím techniky diferenční pulsní voltamerie (DPV) ve vodném prostředí. Jako základní elektrolyt byl zvolen 0,1 mol.dm-3 KCl, který poskytoval nejširší potenciálové okno v katodické oblasti potenciálů. Nízkomolekulární DNA z lososího spermatu byla využita v následujícím modifikační kroku pro vytvoření modifikované elektrody. Poškození DNA bylo provedeno vystavením takto připraveného biosenzoru UV-C záření o vlnové délce 254 nm. Poškozená DNA naadsorbovaná na m-AgSAE byla testována pomocí DPV v elektrochemické cele obsahující ionty Co2+ nebo komplex Co2+ a phen, obojí o koncentraci 1.10-3 mol.dm-3 . Na získaných voltamogramech byla sledována...
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Voltammetric determination of 4-aminopyridine
Kudláčková, Kateřina ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
In this thesis, the voltammetric behavior of 4-aminopyridine was investigated using carbon paste electrode. Differential pulse voltammetry was used for the study. Measurements were carried out in Britton-Robinson butter medium with different pH values. Optimal pH value found was 9. The electrode passivation during consecutive measurements of 4-aminopyridine without the surface renewal was confirmed, while the accumulation time had no influence on peak heights of 4-aminopyridine. Limit of detection was 8,76×10-6 mol dm-3 and limit of quantification was 1,85×10-5 mol dm-3 of 4-aminopyridne under optimal conditions. The linearity of the calibration curve was evaluated using the correlation coefficient.
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