Vývoj elektrochemických metod k studiu antibakteriálních látek v malých objemech

Hlavním cílem této disertační práce je vývoj voltametrických metod pro elektrochemickou studii nových antimykobakteriálních látek hydroxynaftalenkarboxamidů. Tato studie je v první řade zaměřena na miniaturizaci voltametrických metod a konstrukci elektrochemické mikrocely za účelem analýzy biologicky aktivních látek v biologických matricích, se kterou je obvykle spojené omezené množství vzorku. Všechny aspekty voltametrické analýzy musely být prostudovány s důrazem na miniaturizaci. Mikrocely byly zkonstruovány pomocí běžně komerčně dostupných elektrod: elektrody ze skelného uhlíku, jako spolehlivého a podrobně charakterizovaného materiálu, a nové stříbrné pevné amalgámové elektrody. Toto porovnávání bylo provedeno pomocí modelových analytů: 4-nitrofenol, pesticid difenzoquat a 1-hydroxy-N-(4-nitrofenyl)naftalen-2-karboxamid. Důraz byl kladen speciálně na optimalizaci postupů k odstranění signálu kyslíku v kapce roztoku. Byly vyvinuty miniaturizované metody, které měly stejné parametry stanovení těchto látek jako stanovení ve velkém mililitrovém objemu. Takto vyvinuté elektrochemické mikrocely mohou být obecně užívané k voltametrické analýze biologických nebo enviromentálních vzorků, kterých je k dispozici jen omezený objem. Druhá část této práce byla zaměřena na elektrochemickou studii nově...Main goal of this Ph.D. thesis is to develop voltammetric methods for the electrochemical study of novel antimycobacterial compounds hydroxynaphthalene- carboxamides. Firstly, this study was focused on the miniaturization of voltammetric methods and construction of an electrochemical microcell due to usually small volume of samples that are associated with an analysis of biologically active compounds in biological matrices. Therefore, all aspects of the voltammetric procedure were studied in a relation to miniaturization. Microcells were based on commercially available electrodes: glassy carbon electrode as a reliable electrode material with well-described characteristics and a novel silver solid amalgam electrode. This study was carried out with analytes 4-nitrophenol, pesticide difenzoquat, and 1-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide. Attention was paid especially to the optimization of oxygen removal procedures in the drop of a solution. Developed miniaturized methods had the same parameters for the determination of studied compounds as in bigger volumes. The proposed electrochemical microcell can be generally used for voltammetric analysis of those samples of biological or environmental origin that are usually available in very limited volumes. Second part of the thesis was focused...Katedra analytické chemieDepartment of Analytical ChemistryPřírodovědecká fakultaFaculty of Scienc

Využití antimonových filmových elektrod pro stanovení pesticidu trifluralin

Tato diplomová práce se zabývá využitím antimonových filmových elektrod ve voltametrické analýze organických látek, v případě této práce je studován pesticid trifluralin. V studii se našla optimální substrátová elektroda z pěti vybraných elektrod, mezi které patřili zlatá, stříbrná, měděná, leštěná amalgámová elektroda a elektroda ze skelného uhlíku (GCE). Nejlepší charakteristiky byly pozorovány u antimonové filmové elektrody ze skelného uhlíku (SbFGCE), u které byla pozorována vyšší citlivost a nižší mez stanovitelnosti v porovnání s čistou elektrodou. Antimonový film byl stabilní a byla na něm dosáhnutá dobrá opakovatelnost (RSD = 5,2 %). Proběhla optimalizace parametrů elektrochemické přípravy filmu na SbFGCE v depozičním roztoku. Pomocí takto připravené elektrody bylo optimalizováno stanovení koncentrace trifluralinu. Nejvyšší signál analyt poskytoval při diferenční pulsní voltametrii v roztoku methanolu a 0,1 M kyseliny chlorovodíkové v poměru 1:1. Byl dosáhnut limit stanovitelnosti při koncentraci 1,2·10-6 mol·l-1 . Přímé voltametrické stanovení proběhlo aj v modelovém vzorku říční vody. Nižší meze stanovitelnosti byly dosáhnuty s využitím extrakce tuhou fází (SPE). Výtěžnost extrakce v deionizované vodě se pohybovala na úrovni 86 ± 8 % při 125 násobném prekoncentračním faktoru a limit...Antimony film electrode was studied for the use in a voltammetric analysis of organic compounds. The substance chosen as an analyte was trifluralin, which is used as a pesticide. The comparison of different substrate electrodes was carried out between five electrodes, which were gold, silver, copper, polished amalgam and glassy carbon electrode (GCE). Best performance was observed on antimony film glassy carbon electrode (SbFGCE). It provided higher sensitivity and lower limit of quantification in comparison with bare GCE. The antimony film was stable and it provided good reproducibility (RSD = 5.2 %). Parameters of an electrochemical preparation of SbFGCE were optimized. Conditions for determination of concentration of trifluralin were optimized on newly prepared SbFGCE. The best conditions were in a solution of methanol and 0.1 M hydrochloric acid in 1:1 ratio measured by differential pulse voltammetry. The limit of quantification was determined as 1.2·10-6 mol·l-1 . A direct voltammetric measurement on SbFGCE was carried out in a model river sample. Lower limits of quantification were achieved with solid phase extraction (SPE). Recovery values were 86 ± 8 % in deionized water with a preconcentration factor of 125. The limit of quantification was lowered to value 1.1·10-8 mol·l-1 . The extraction...Department of Analytical ChemistryKatedra analytické chemiePřírodovědecká fakultaFaculty of Scienc

Vývoj elektrochemických metod k studiu antibakteriálních látek v malých objemech

Hlavním cílem této disertační práce je vývoj voltametrických metod pro elektrochemickou studii nových antimykobakteriálních látek hydroxynaftalenkarboxamidů. Tato studie je v první řade zaměřena na miniaturizaci voltametrických metod a konstrukci elektrochemické mikrocely za účelem analýzy biologicky aktivních látek v biologických matricích, se kterou je obvykle spojené omezené množství vzorku. Všechny aspekty voltametrické analýzy musely být prostudovány s důrazem na miniaturizaci. Mikrocely byly zkonstruovány pomocí běžně komerčně dostupných elektrod: elektrody ze skelného uhlíku, jako spolehlivého a podrobně charakterizovaného materiálu, a nové stříbrné pevné amalgámové elektrody. Toto porovnávání bylo provedeno pomocí modelových analytů: 4-nitrofenol, pesticid difenzoquat a 1-hydroxy-N-(4-nitrofenyl)naftalen-2-karboxamid. Důraz byl kladen speciálně na optimalizaci postupů k odstranění signálu kyslíku v kapce roztoku. Byly vyvinuty miniaturizované metody, které měly stejné parametry stanovení těchto látek jako stanovení ve velkém mililitrovém objemu. Takto vyvinuté elektrochemické mikrocely mohou být obecně užívané k voltametrické analýze biologických nebo enviromentálních vzorků, kterých je k dispozici jen omezený objem. Druhá část této práce byla zaměřena na elektrochemickou studii nově...Main goal of this Ph.D. thesis is to develop voltammetric methods for the electrochemical study of novel antimycobacterial compounds hydroxynaphthalene- carboxamides. Firstly, this study was focused on the miniaturization of voltammetric methods and construction of an electrochemical microcell due to usually small volume of samples that are associated with an analysis of biologically active compounds in biological matrices. Therefore, all aspects of the voltammetric procedure were studied in a relation to miniaturization. Microcells were based on commercially available electrodes: glassy carbon electrode as a reliable electrode material with well-described characteristics and a novel silver solid amalgam electrode. This study was carried out with analytes 4-nitrophenol, pesticide difenzoquat, and 1-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide. Attention was paid especially to the optimization of oxygen removal procedures in the drop of a solution. Developed miniaturized methods had the same parameters for the determination of studied compounds as in bigger volumes. The proposed electrochemical microcell can be generally used for voltammetric analysis of those samples of biological or environmental origin that are usually available in very limited volumes. Second part of the thesis was focused...Katedra analytické chemieDepartment of Analytical ChemistryFaculty of SciencePřírodovědecká fakult

Voltammetric determination of pesticides using meniscus modified silver solid amalgam electrode

The aim of this bachelor thesis is to find the optimal conditions for voltammetric determination of pesticides cypermethrin, deltamethrin and difenzoquat on meniscus modified silver solid amalgam electrode using differential pulse voltammetry. Conditions under which cypermethrin and deltamethrin could be determinated were found in previously published works. These conditions were reproduced. Substances were studied in methanol and dimethylformamide solutions. The optimal conditions for determination of these two substances were not found. Voltammetric behaviour of difenzoquat was studied in different pH using Britton-Robinson buffer. The optimal pH 11 was chosen. The reproducibility of measurement was studied at concentration 1·10-4 mol·l-1 , peak was stable (RSD = 3%). Sharp maxima were found at high concentrations of analyte, addition of gelatine led to one well- defined peak. Peak potencial was - 1,4 V. Calibration dependences were measured at concentrations 2·10-7 mol·l-1 - 1·10-4 mol·l-1 . Limit of determination was 6,1·10-7 mol·l-1 . Linear dynamic range of this method was found between concentrations 6,1·10-7 - 2·10-5 mol·l-1 . Difenzoquat was determined in model samples of drinking and river water. Limits of detemination were achieved at concentrations 3,4·10-7 mol·l-1 in drinking water and..

Development of electrochemical methods for study of antibacterial compounds in small volumes

Main goal of this Ph.D. thesis is to develop voltammetric methods for the electrochemical study of novel antimycobacterial compounds hydroxynaphthalene- carboxamides. Firstly, this study was focused on the miniaturization of voltammetric methods and construction of an electrochemical microcell due to usually small volume of samples that are associated with an analysis of biologically active compounds in biological matrices. Therefore, all aspects of the voltammetric procedure were studied in a relation to miniaturization. Microcells were based on commercially available electrodes: glassy carbon electrode as a reliable electrode material with well-described characteristics and a novel silver solid amalgam electrode. This study was carried out with analytes 4-nitrophenol, pesticide difenzoquat, and 1-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide. Attention was paid especially to the optimization of oxygen removal procedures in the drop of a solution. Developed miniaturized methods had the same parameters for the determination of studied compounds as in bigger volumes. The proposed electrochemical microcell can be generally used for voltammetric analysis of those samples of biological or environmental origin that are usually available in very limited volumes. Second part of the thesis was focused..

Development of electrochemical methods for study of antibacterial compounds in small volumes

Main goal of this Ph.D. thesis is to develop voltammetric methods for the electrochemical study of novel antimycobacterial compounds hydroxynaphthalene- carboxamides. Firstly, this study was focused on the miniaturization of voltammetric methods and construction of an electrochemical microcell due to usually small volume of samples that are associated with an analysis of biologically active compounds in biological matrices. Therefore, all aspects of the voltammetric procedure were studied in a relation to miniaturization. Microcells were based on commercially available electrodes: glassy carbon electrode as a reliable electrode material with well-described characteristics and a novel silver solid amalgam electrode. This study was carried out with analytes 4-nitrophenol, pesticide difenzoquat, and 1-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide. Attention was paid especially to the optimization of oxygen removal procedures in the drop of a solution. Developed miniaturized methods had the same parameters for the determination of studied compounds as in bigger volumes. The proposed electrochemical microcell can be generally used for voltammetric analysis of those samples of biological or environmental origin that are usually available in very limited volumes. Second part of the thesis was focused..

Voltametrické stanovení pesticidů na meniskem modifikované stříbrné pevné amalgamové elektrodě

Tato bakalářská práce se zabývá optimalizaci podmínek pro voltametrické stanovení pesticidů cypermethrinu, deltamethrinu a difenzoquatu na meniskem modifikované stříbrné pevné amalgámové elektrodě metodou diferenční pulsní voltametrie. Při stanovení cypermethrinu a deltamethrinu se vycházelo z podmínek předešle publikovaných prací. Látky byly studovány ve vodních roztocích methanolu a dimethylformamidu. Tyto podmínky byly zreprodukovány, optimální podmínky pro stanovení těchto dvou látek ale nebyly nalezeny. Voltametrické chování difenzoquatu v Britton-Robinsonovom pufri bylo sledováno v závislosti na pH. Za optimální podmínky bylo určeno pH 11. Při koncentraci 1·10-4 mol·l-1 se zkoumala opakovatelnost měření, pík byl stabilní (RSD = 3%). Ve vyšších koncentracích analytu byly pozorovány vířivý maxima, které byly eliminovány přídavkem želatiny. Potenciál píku difenzoquatu byl při hodnotě - 1,4 V. Kalibrační závislosti byly studovány při koncentracích 2·10-7 mol·l-1 - 1·10-4 mol·l-1 . Bylo dosáhnuto limitu stanovitelnosti 6,1·10-7 mol·l-1 . Lineární dynamický rozsah stanovení byl určen v užším rozmezí koncentrací 6,1·10-7 - 2·10-5 mol·l-1 . Analyt byl stanovován v modelových vzorcích pitné a říčné vody. Dosáhnuté byly limity stanovitelnosti 3,4·10-7 mol·l-1 v pitné vodě a 4,7·10-7 mol·l-1 v říční vodě.The aim of this bachelor thesis is to find the optimal conditions for voltammetric determination of pesticides cypermethrin, deltamethrin and difenzoquat on meniscus modified silver solid amalgam electrode using differential pulse voltammetry. Conditions under which cypermethrin and deltamethrin could be determinated were found in previously published works. These conditions were reproduced. Substances were studied in methanol and dimethylformamide solutions. The optimal conditions for determination of these two substances were not found. Voltammetric behaviour of difenzoquat was studied in different pH using Britton-Robinson buffer. The optimal pH 11 was chosen. The reproducibility of measurement was studied at concentration 1·10-4 mol·l-1 , peak was stable (RSD = 3%). Sharp maxima were found at high concentrations of analyte, addition of gelatine led to one well- defined peak. Peak potencial was - 1,4 V. Calibration dependences were measured at concentrations 2·10-7 mol·l-1 - 1·10-4 mol·l-1 . Limit of determination was 6,1·10-7 mol·l-1 . Linear dynamic range of this method was found between concentrations 6,1·10-7 - 2·10-5 mol·l-1 . Difenzoquat was determined in model samples of drinking and river water. Limits of detemination were achieved at concentrations 3,4·10-7 mol·l-1 in drinking water and...Department of Analytical ChemistryKatedra analytické chemieFaculty of SciencePřírodovědecká fakult

Development of electrochemical methods for study of antibacterial compounds in small volumes

Main goal of this Ph.D. thesis is to develop voltammetric methods for the electrochemical study of novel antimycobacterial compounds hydroxynaphthalene- carboxamides. Firstly, this study was focused on the miniaturization of voltammetric methods and construction of an electrochemical microcell due to usually small volume of samples that are associated with an analysis of biologically active compounds in biological matrices. Therefore, all aspects of the voltammetric procedure were studied in a relation to miniaturization. Microcells were based on commercially available electrodes: glassy carbon electrode as a reliable electrode material with well-described characteristics and a novel silver solid amalgam electrode. This study was carried out with analytes 4-nitrophenol, pesticide difenzoquat, and 1-hydroxy-N-(4-nitrophenyl)naphthalene-2-carboxamide. Attention was paid especially to the optimization of oxygen removal procedures in the drop of a solution. Developed miniaturized methods had the same parameters for the determination of studied compounds as in bigger volumes. The proposed electrochemical microcell can be generally used for voltammetric analysis of those samples of biological or environmental origin that are usually available in very limited volumes. Second part of the thesis was focused..

Application of Antimony Film Electrodes for Determination of Pesticide Trifluralin

Antimony film electrode was studied for the use in a voltammetric analysis of organic compounds. The substance chosen as an analyte was trifluralin, which is used as a pesticide. The comparison of different substrate electrodes was carried out between five electrodes, which were gold, silver, copper, polished amalgam and glassy carbon electrode (GCE). Best performance was observed on antimony film glassy carbon electrode (SbFGCE). It provided higher sensitivity and lower limit of quantification in comparison with bare GCE. The antimony film was stable and it provided good reproducibility (RSD = 5.2 %). Parameters of an electrochemical preparation of SbFGCE were optimized. Conditions for determination of concentration of trifluralin were optimized on newly prepared SbFGCE. The best conditions were in a solution of methanol and 0.1 M hydrochloric acid in 1:1 ratio measured by differential pulse voltammetry. The limit of quantification was determined as 1.2·10-6 mol·l-1 . A direct voltammetric measurement on SbFGCE was carried out in a model river sample. Lower limits of quantification were achieved with solid phase extraction (SPE). Recovery values were 86 ± 8 % in deionized water with a preconcentration factor of 125. The limit of quantification was lowered to value 1.1·10-8 mol·l-1 . The extraction..

Amperometric Sensor for Selective On-Site Analysis of Free Sulfite in Wines

International audienceAccurate and rapid on-site analysis of free SO 2 content is crucial in the process of winemaking from a producer and consumer perspective. Herein, we present an amperometric sensor based on commercially available screenprinted electrodes coupled with an electrochemical oxygen filter. The developed amperometric method gave a linear response in a concentration range up to 200 mg L −1 with a limit of quantification of 7.5 mg L −1. The applicability of the developed sensor was successfully tested on 27 white and red wine samples and compared to the Ripper method (iodometry) that is a standard procedure for free SO 2 determination. The sensor exhibits similar precision and accuracy but shows no interference from oxidizable species such as ascorbic acid, which is a major advantage over iodometric titration. The performance of the sensor was in addition positively evaluated during on-site analysis in a winery