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Voltammetric detection of 7α-hydroxycholesterol on boron doped diamond electrode
Serbanová, Lucie ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
This bachelor's thesis is dedicated to the electrochemical determination of 7α-hydroxycholesterol (7α-OHC) using boron-doped diamond electrode (BDDE). The work includes the optimization of experimental conditions and the measurement of the concentration dependence of 7α-OHC. The influence of various factors, such as water content in the solution and scan rate, on the electrochemical response of 7α-OHC was investigated. Various electrochemical methods, including cyclic voltammetry and differential pulse voltammetry, were used in the experiments. The electrochemical behavior of 7α-OHC in a solution of chloric acid and acetonitrile were analyzed. Important factors such as electrode passivation and response stability were carefully evaluated. The measurement of concentration dependence of 7α-OHC exhibited a linear response within the concentration range from 2∙10−5 mol l−1 to 1∙10−4 mol l−1 . Limits of detection (LOD) and quantification (LOQ) of 1,33 µmol l−1 and 4,43 µmol l−1 were determined. Comparison with other methods revealed that the electrochemical determination of 7α-OHC on BDDE achieves comparable sensitivity. The results of this work provide crucial insights into the electrochemical behavior of 7α-OHC, highlighting the advantages of BDDE for sensitive and reliable determination of...
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Analysis of composition of residues of inorganic pharmaceuticals from the 18th century
Janoušková, Eva ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
In this bachelor thesis, sixteen samples of inorganic pharmaceuticals from the 18th century were analyzed by inductively coupled plasma mass spectrometry, atomic absorption spectrometry, atomic emission spectrometry, UV/VIS spectrometry, capillary zone electrophoresis, titrations, and gravimetric analysis. The analysis confirmed that the composition of fourteen of the analyzed samples corresponded with their respective Latin inscriptions on the apothecary jars, while two of the samples proved to be a completely different substance. All samples, except for one, contained a relatively high number of impurities. These impurities helped determine if the source of the sample was a mineral commonly occurring in nature or a chemical reaction. Keywords: History of pharmacy, ICP-MS, F-AAS, F-AES, UV/VIS spectrometry, historical pharmaceuticals
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Sequential Injection Analysis for Spectrophotometric Determination of Biseptol Components
Kroiherová, Anna ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
A method using the sequential injection analysis technique for the spectrometric determination of two analytes, sulfamethoxazol and trimethoprim, in a mixture in the drug Biseptol® 480 without the need for their separation, was developed and optimized. Both analytes absorb in the UV spectrum, but only sulfamethoxazol, as primary amine, gives a colour product after derivatization reaction with sodium nitrite and N-(1-naphthyl)ethylenediamine, that can be detected in the VIS spectrum. The concentration of sulfamethoxazol is directly proportional to the absorbance of the colour product and by subtracting this concentration from the concentration of both analytes measured in the UV spectrum, the concentration of trimethoprim in the sample can be determined.
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Development of voltammetric methods for detection of bile acids and their conjugates
Petráňová, Karolína ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this thesis is to study the electrochemical properties of bile acids and their conjugates. Specifically, cholic acid, chenodeoxycholic acid, taurocholic acid, taurochenodeoxycholic acid, glycocholic acid, and glycochenodeoxycholic acid were studied. The measurements were carried out on a boron-doped diamond electrode in an environment of acetonitrile and perchloric acid, with a water content of 0.55% in the solution by method of cyclic voltammetry. In order for bile acids to be electrochemically active, they must first be dehydrated, which takes place in a reaction with perchloric acid. This reaction requires a relatively long time, so it was accelerated by heating the compounds. The goal of this work was to determine the conditions under which the dehydration products of bile acids can be detected. The water content that can be added to the solution after dehydration to keep the voltammetric signal stable was determined. Furthermore, it was found that the voltammetric determination can be carried out even at a pH that is not extremely acidic in which is the the dehydration carried out. Finally, calibration dependencies were compiled.
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Analysis of phenobarbital in historical residues of pharmaceuticals in various dosage forms
Belianský, Michal ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
Belianský M.: Analysis of phenobarbital in historical residues of pharmaceuticals in various dosage forms. Master Thesis. Prague, Charles University, Faculty of Science 2022. Abstract: The work analysed four historical pharmaceutical residue samples up to 60 years old. All of the samples analysed contained phenobarbital, but in different dosage forms. The dosage forms of the selected historical pharmaceuticals were tablets, dragees, suppositories, and solution. The HPLC method with UV or mass detection was used for the analysis. Separation of the analytes took place in the SupelcosilTM LC-18 column using binary gradient elution. No degradation product was identified in three of the four historical designs analysed, while other substances not declared in the pharmacopoeias were identified. Two phenobarbital degradation products, feneturide and 3-aminopentanoic acid, were identified in the oldest sample, solution. The concentration of phenobarbital in this preparation decreased by 12.5% compared to the original content declared. Finally, analytes of historical pharmaceutical remains have been selected, quantified, and compared with the declared content. Key words: degradation, HPLC, mass spectrometry, phenobarbital
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Voltammetric behaviour of cholesterol and lanosterol on boron doped diamond electrode
Kubešová, Jana ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this thesis is to investigate procedures leading to regeneration of boron- doped-diamond's (BDD electrode) surface and study of voltammetric behaviour of cholesterol and lanosterol on BDD electrode. Three options of regeneration of electrode's surface were were studied: the stirring, the mechanical polishing using alumina and the anodic oxidation. The anodic oxidation was studied using electrolytes: 0,1 mol l−1 perchloric acid in acetonitrile, 0,1 mol l−1 sodium perchlorate in acetonitrile and tetrahexylammonium hexafluorofosphate in acetonitrile. Each electrolyte was studied with 0 or 0,43 % and 20 % volume of water. Further, voltammetric behaviour of cholesterol on BDD electrode in the presence of 0,1 mol l−1 perchloric acid in acetonitrile was investigate. The second part of the thesis was the study of voltammetric behaviour of lanosterol on BDD electrode in the presence of 0,1 mol l−1 perchloric acid in acetonitrile and 0,1 mol l−1 sodium perchlorate in acetonitrile. The study was performed using cyclic voltammery. Lanosterol provides two anodic signals in the presence of both electrolytes, the first one at the potential of +1200 mV, the second one at the potential of +1500 mV. The stability of lanosterol in the presence of perchloric acid and sodium perchlorate was studied by...
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Analysis of historical pharmaceutical preparation containing chicory from the 18th century
Lener, Tomáš ; Nesměrák, Karel (advisor) ; Kubíčková, Anna (referee)
A historical pharmaceutical preparation - chicory extract - from the 18th century whose authenticity was investigated was qualitatively analyzed using HPLC with UV/VIS and MS2 detection. A current dry chicory root was used as a source of selected chicory chemotaxonomic markers and an indicator of the success of extraction with different solvents. The authenticity of the historical extract was proved by a water solubility test. A VIS spectrometric determination of inulin was used and the inuline content was determined to be 52.4% in the current dry chicory root and 7.45% in the historical extract. The detection wavelength 254 and 320 nm was selected from measured UV/VIS spectra of selected standards and the literature. The authenticity of the historical chicory extract was proven by tandem mass spectrometry, and, moreover, arteincultone - a new chicory chemotaxonomic marker - was identified. Key words: HPLC-MS, HPLC-UV/VIS, UV/VIS Spectrometry, Chicory, Historical extract, Chicory root, Arteincultone
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Sequential Injection Analysis for Spectrophotometric and Spectrofluorometric Determination of Chlorpromazine, Levomepromazine and Promethazine
Kroiherová, Anna ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
In this diploma thesis, a method using the sequence analysis technique for spectrometric and spectrofluorimetric analysis of three selected analytes from the group of phenothiazines (chlorpromazine, levomepromazine and promethazine) was developed and optimized. The determination is based on the oxidation reaction of phenothiazines with cerium(IV) ions in an acidic medium, which produces a color product that is detected by VIS spectrometry or spectrofluorimetry. The measurement conditions for sequence analysis were optimized and evaluation was performed by nonlinear calibration in the dynamic range of 3−320 mg dm−3 for VIS spectrometric detection and 0.3−50.0 mg dm−3 for spectrofluorimetric detection. The influence of water-soluble common excipients (fructose, glucose, lactose), which are often part of medicinal products, was investigated. The developed sequential injection analysis with both detections was successfully applied to authentic samples of drugs (Plegomazine, Tisercine and Prothazine) containing the analyzed phenothiazines. The measurement results were in good agreement with the used reference method of direct UV spectrometry. The advantages of developed SIA method with VIS spectrometric and spectrofluorometric detection are its automation, speed, low consumption of reagent and a wide...
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Sorption of radionuclid 85Sr to soils from area nuclear power plant Temelín
Reidingerová, Markéta ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
This thesis is focused on the study of sorption of radionuclide 85 Sr in soil collected in the area of a nuclear power plant Temelín. A single-batch method experiment was used when a solution of radionuclide 85 Sr of known activity was added to the soil. The experiments focussed on the influence of pH with the size of the sorption and the influence of the time of the contact of the solution with the sorption. During the experiment with the value of pH closest to the pH of underground water from the nuclear power plant Temelín, the sorption of soil was somewhere between 31 to 44 %. When the time influence on the sorption was examined, radionuclide 85 Sr was sorbed very quickly. For the comparison of the sorption size in connection with the time, for which it was chosen 120 minutes, the sorption was almost constant, reaching 40 to 48 %. Key words Radioactivity, radionuclide 85 Sr, sorption, nuclear power plant Temelín
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