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Elektrochemické stanovení Fomesafenu / Electrochemical Determination of FomesafenMaška, Jan January 2013 (has links)
The submitted work deals with the application of voltammetric determination of Fomesafen using non-traditional mercury meniscus modified silver solid amalgam electrode on model samples of Fomesafen in real aqueous matrices of drinking and river water. This method of measurement has been developed and optimized in my bachelor thesis, which the diploma thesis is related to. Fomesafen belongs to a group of herbicides used on a mass scale in the late 20th century in the USA and in many countries around the world still used even today. Among its side effects according to the EPA include, among others, potential carcinogenicity to humans and confirmed carcinogenicity to some mammals (such as rats) which led to a legislative regulation on its use in many countries around the world including the USA, the European Union and many others. Silver solid amalgam electrode has been developed with the intention to limit the use of mercury in accordance with new legislation of the European Union and the concept of green analytical chemistry. Despite the low levels of mercury mainly bound in the form of virtually harmless silver amalgam electrode retains very similar electrochemical properties with proven mercury electrodes. As part of the thesis, direct determination of a number of partial extraction of Fomesafen...
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Voltametrické stanovení 5-nitroimidazolu - strukturní jednotky nitroimidazolových léčiv / Voltammetric Determination of 5-Nitroimidazole - The Structural Unit of Nitroimidazole DrugsŠmídková, Monika January 2013 (has links)
Presented Diploma Thesis deals with the study of electrochemical behavior of 5-nitroimidazole (5-NI), with the search for optimal conditions for its determination using techniques of DC voltammetry (DCV) and differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) and at a boron-doped diamond film electrode (BDDFE), and with the comparison of reached limits of quantification (LQs). The optimal conditions found for measuring calibration dependences of 5-NI at the m-AgSAE in deionized water were as follows: Britton-Robinson buffer of pH 7.0 and 10.0 for DCV and DPV, respectively. At both thechniques, it is advisable to use an electrochemical regeneration of the electrode surface by the application of a couple of regeneration potentials Ereg,1 = 0 mV and Ereg,2 = −800 mV. The calibration dependences were measured in the concentration range from 1·10−6 to 1·10−4 mol·l−1 , with the LQs of 1.0·10−6 mol·l−1 for DCV at the m-AgSAE and 1.5·10−6 mol·l−1 for DPV at the m-AgSAE. The concentration dependences of 5-NI at the BDDFE were measured using the DCV technique in the BR buffer of pH 3.0. For the DPV technique, the optimal medium seemed to be the BR buffer of pH 2.0, however, because of the presence of an interfering peak in the supporting electrolyte,...
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Voltametrické stanovení vybraných psychofarmak pomocí uhlíkových elektrod / Voltammetric Determination of Selected Psychopharmaceuticals Using Carbon ElectrodesMatouš, Petr January 2019 (has links)
Differential pulse voltammetry (DPV) was used for developing a method for the determination of phenothiazine derivatives, namely chlorpromazine (CHP) and levomepromazine (LMP), using a glassy carbon electrode (GCE) and a graphite electrode, both with a 2 mm disc diameter. Comparison of quantification limits (LQ) for both substances on both electrodes was performed. After optimizing and processing the results, the optimal conditions for measuring calibrations were as follows: Britton- Robinson (BR) buffer at pH 4.0. Calibration dependences were measured inthe concentration range from 1·10-7 to 1·10-4 mol·dm-3 . There was no need for electrochemical electrode regeneration or matrix pretreatment. The results showed higher measurement sensitivity for CHP, and the graphite electrode also showed higher sensitivity. Although there were measured lower concentrations with the graphite electrode in comparison to the GCE, because of the low repeatability of the measurements in the lower concentration range 1-10·10-7 mol·dm-3 , the LQ is comparable to the results reached on the GCE. Besides to the BR buffer, measurements in other matrices (drinking water and river water) were also made. The following LQ values were achieved: 1.0·10-6 mol·dm-3 (in BR buffer), 1.1·10-6 -1.4·10-6 mol·dm-3 (in drinking water) and...
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Aplica??o da t?cnica eletroanal?tica de pulso diferencial usando o eletrodo de carbono v?treo modificado com ciste?na para monitorar a degrada??o eletroqu?mica de ?cido ox?licoNeves, Nathalia Costa Viana 31 July 2013 (has links)
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Previous issue date: 2013-07-31 / In this paper, the technique of differential pulse voltammetry (DPV) has been
studied for monitoring the concentration of oxalic acid (OA) during their
electrochemical oxidation (EO) in acidic medium using platinum anode supported on
titanium (Ti / Pt). The DPV was standardized and optimized using a glassy carbon
electrode modified with cysteine. The modification with cysteine was developed
electrochemically, forming a polymeric film on the surface of the glassy carbon
electrode. The formation of the polymer film was confirmed by analysis of scanning
electron microscope and atomic force microscope, confirming the modification of the
electrode. The electrochemical degradation was developed using different current
densities 10, 20 30 and 40 mA cm -2 electrode with Ti / Pt observing the degradation
of oxalic acid, and monitored using the method of KMnO4 titration. However, the
analyzes with DPV showed the same behavior elimination of oxalic acid titration.
Compared with the titration method classical observed and DPV could be a good fit,
confidence limits of detection and confirming the applicability of the technique
electroanalytical for monitoring the degradation of oxalic acid / No presente trabalho, a t?cnica de voltametria de pulso diferencial (DPV) foi
estudada para o monitoramento da concentra??o de ?cido ox?lico (OA) durante a
sua oxida??o eletroqu?mica (EO) em meio ?cido utilizando o ?nodo de platina
suportada em tit?nio (Ti/Pt). A t?cnica de DPV foi padronizada e otimizada usando
um eletrodo de carbono v?treo modificado com ciste?na. A modifica??o com ciste?na
foi desenvolvida eletroquimicamente, formando um filme polim?rico na superf?cie do
eletrodo de carbono v?treo. A forma??o do filme polim?rico foi confirmada por an?lise
de Microsc?pio Eletr?nico de Varredura e Microsc?pio de For?a At?mica,
confirmando a modifica??o na superf?cie do eletrodo. A degrada??o eletroqu?mica foi
desenvolvida usando diferentes densidades de corrente, 10, 20 e 30 mA cm-? com
eletrodo de Ti/Pt, observando a degrada??o do ?cido ox?lico, sendo monitorado
empregando a metodologia de titula??o com KmnO4. No entanto, as an?lises com
DPV mostraram o mesmo comportamento de elimina??o do acido ox?lico,
observado com a titula??o. Comparado com o m?todo de titula??o cl?ssica e DPV
conseguiu-se um bom ajuste, intervalos de confian?a e limites de detec??o
confirmando a aplicabilidade da t?cnica eletroanal?tica para o monitoramento da
degrada??o de ?cido ox?lico
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Voltametrické stanovení genotoxických nitrobifenylů / Voltammetric Determination of Genotoxic NitrobiphenylsHoráková, Eva January 2012 (has links)
The presented diploma thesis is devoted to study of determination of 4-nitrobiphenyl (4-NBP) in model river water by DC voltammetry (DCV) and differential pulse voltammetry (DPV) at m-AgSAE (diploma thesis relates to bachelor thesis, in it DCV and DPV methods for determination of 4-NBP in deionized water were developed). Limit of determination (LOD) is 2·10-7 mol·l-1 by DCV and 4·10-7 mol·l-1 by DPV. The adsorptive stripping DPV (AdSDPV) technique was tested to archive lower LOD the AdSDPV, optimal conditions were not found. Electrochemical behavior of 2-nitrobiphenyl (2-NBP) at m-AgSAE was studied. Optimal conditions for its determination by both techniques DCV and DPV were found in methanol-0,01 mol·l-1 LiOH (1:9) and in this medium peak current dependence in 1·10-7 mol·l-1 to 1·10-4 mol·l-1 2-NBP (LOD ≈ 2·10-7 mol·l-1 by DCV and 1·10-7 mol·l-1 by DPV) concentration range was measured. Developed methods were successfully tested for determination of 2-NBP in drinking and river water samples. For both mediums obtained LODs were 2·10-7 mol·l-1 by DCV and 1·10-7 mol·l-1 by DPV. AdSDPV technique was unsuccessfully tested to achieve lower LOD. Optimal conditions for simultaneous determination of 4-NBP and 2-NBP by DPV technique at m-AgSAE were found: methanol-0,25 mol·l-1 acetate buffer (pH = 6,0) 3:7....
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Development of electrochemical ZnSe Quantam dots biosensors for low-level detection of 17β-Estradiol estrogenic endocrine disrupting compoundJijana, Abongile Nwabisa January 2010 (has links)
<p>The main thesis hub was on development of two electrochemical biosensors for the determination of 17&beta / -estradiol: an estrogenic endocrine disrupting compound. Endocronology have significantly shown that the endocrine disruptors contribute tremendously to health problems encountered by living species today, problems such as breast cancer, reproductive abnormalities, a decline in male population most significant to aquatic vertebrates, reduced fertility and other infinite abnormalities recurring in the reproductive system of mostly male species. The first biosensor developed for the detection of 17&beta / -estradiol endocrine disrupting compound / consisted of an electro-active polymeric 3-mercaptoprorionic acid capped zinc selenide quantum dots cross linked to horseradish peroxidase (HRP) enzyme as a bio-recognition element. The second biosensor developed was comprised of cysteamine self assembled to gold electrode, with 3-mercaptopropionic acid capped zinc selenide quantum dots cross linked to cytochrome P450-3A4 (CYP3A4) enzyme in the presence of 1-ethyl-3-(3- dimethylaminopropyl)carbodiimide hydrochloride and succinimide.</p>
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Development of electrochemical ZnSe Quantam dots biosensors for low-level detection of 17β-Estradiol estrogenic endocrine disrupting compoundJijana, Abongile Nwabisa January 2010 (has links)
<p>The main thesis hub was on development of two electrochemical biosensors for the determination of 17&beta / -estradiol: an estrogenic endocrine disrupting compound. Endocronology have significantly shown that the endocrine disruptors contribute tremendously to health problems encountered by living species today, problems such as breast cancer, reproductive abnormalities, a decline in male population most significant to aquatic vertebrates, reduced fertility and other infinite abnormalities recurring in the reproductive system of mostly male species. The first biosensor developed for the detection of 17&beta / -estradiol endocrine disrupting compound / consisted of an electro-active polymeric 3-mercaptoprorionic acid capped zinc selenide quantum dots cross linked to horseradish peroxidase (HRP) enzyme as a bio-recognition element. The second biosensor developed was comprised of cysteamine self assembled to gold electrode, with 3-mercaptopropionic acid capped zinc selenide quantum dots cross linked to cytochrome P450-3A4 (CYP3A4) enzyme in the presence of 1-ethyl-3-(3- dimethylaminopropyl)carbodiimide hydrochloride and succinimide.</p>
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Development of electrochemical ZnSe Quantam dots biosensors for low-level detection of 17β-Estradiol estrogenic endocrine disrupting compoundJijana, Abongile Nwabisa January 2010 (has links)
Magister Scientiae - MSc / The main thesis hub was on development of two electrochemical biosensors for the determination of 17β-estradiol-estradiol: an estrogenic endocrine disrupting compound. Endocronology have significantly shown that the endocrine disruptors contribute tremendously to health problems encountered by living species today, problems such as breast cancer, reproductive abnormalities, a decline in male population most significant to aquatic vertebrates, reduced fertility and other infinite abnormalities recurring in the reproductive system of mostly male species. The first biosensor developed for the detection of 17β-estradiol-estradiol endocrine disrupting compound; consisted of an electro-active polymeric 3-mercaptoprorionic acid capped zinc selenide quantum dots cross linked to horseradish peroxidase (HRP) enzyme as a bio-recognition element. The second biosensor developed was comprised of cysteamine self assembled to gold electrode, with 3-mercaptopropionic acid capped zinc selenide quantum dots cross linked to cytochrome P450-3A4 (CYP3A4) enzyme in the presence of 1-ethyl-3-(3- dimethylaminopropyl)carbodiimide hydrochloride and succinimide. / South Africa
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Metallic nanoparticles with polymeric shell: A multifunctional platform for application to biosensorNgema, Xolani Terrance January 2018 (has links)
Philosophiae Doctor - PhD (Chemistry) / Tuberculosis (TB) is an airborne disease caused by Mycobacterium tuberculosis (MTB) that
usually affects the lungs leading to severe coughing, fever and chest pains. It was estimated
that over 9.6 million people worldwide developed TB and 1.5 million died from the infectious
disease of which 12 % were co-infected with human immunodeficiency virus (HIV) in the year
2015. In 2016 the statistics increased to a total of 1.7 million people reportedly died from TB
with an estimated 10.4 million new cases of TB diagnosed worldwide. The development of the
efficient point-of-care systems that are ultra-sensitive, cheap and readily available is essential
in order to address and control the spread of the tuberculosis (TB) disease and multidrugresistant
tuberculosis.
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Quantum dots-amplified electrochemical cytochrome P450 phenotype sensor for tamoxifen, a breast cancer drugFeleni, Usisipho January 2017 (has links)
Philosophiae Doctor - PhD / Breast cancer is regarded as the most common cancer in South Africa and its rate of
occurrence is increasing. About one in every 31 South African women are at the risk of
developing breast cancer and early diagnosis and treatment guarantee 90% survival rate.
Tamoxifen is the drugs of choice for the treatment of all stages of breast cancer. The drug
binds with estrogen receptor (ER) to minimize the transcription of estrogen dependent genes.
However, nearly 50% of ER-positive breast cancer patients either become resistant or fail to
respond to tamoxifen resulting in a serious clinical challenge in breast cancer management.
The Grand Health Challenges of South Africa includes the development of cost effective
diagnostic systems suitable for early detection of diseases and drug resistivity for timely
invention and better patient management. / 2020-08-31
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