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Possibilities of Electrochemical Analysis Using a System of Electrodes With Non-Specific Response
Ederer, Jakub ; Nesměrák, Karel (advisor) ; Ludvík, Jiří (referee)
The master thesis present the possibilities of processing of electrochemical data from a group of four electrodes with non-selective response (simple sensor array) for electrochemical analysis with potential application of the results achieved in the construction of the sensor field type "electronic tongue". This simple system was applied to the sample simulating the food product. Electrochemical data were processed through mathematical operations such as Gaussian approximation, deconvolution or using basic mathematical operations.
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Mercury Speciation in a Historical Medical Preparation
Landl, Richard ; Červený, Václav (advisor) ; Nesměrák, Karel (referee)
In this final work, extraction methods for the determination of the total mercury concentration and its speciation analysis in a sample of historical medicinal product are evaluated. The first half of the experimental part is devoted to the determination of total mercury concentration in a sample of the historical medicinal product Naso Merfen unguentum using different evaluation methods with different standards used. Extraction with a mixture of hydrochloric acid and nitric acid was used for this determination. In this sample mercury is in the form of sparingly soluble phenylmercuric borate. The concentration (5.4 ± 2.0) · 10−2 % phenylmercuric borate was determined by evaluating the individual procedures. The next step was the speciation analysis of the historical drug sample and other samples that were used as reference materials. Extractions with tetramethyl ammonium hydroxide were used for specific analysis. From the determination of the mercury concentration in the reference materials, the extraction yields for both extraction methods was evaluated. For the standards of mercuric sulphide and phenylmercuric borate, both methods of extraction and determination were unsuitable due to their very low solubility. For mercuric sulfide, the yield of extraction with tetramethyl ammonium hydroxide was...
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Comparison of methods for the determination of ambroxol in medicinal products
Janoušková, Kristýna ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
This bachelor thesis aimed to compare selected analytical methods for determining the content of ambroxol in medicinal products in terms of trueness and precision of the measurement and measurement time and cost. Three methods were selected for the determination: (1) UV spectrometry using the calibration method, (2) UV spectrometry based on the standard addition method, and (3) high performance liquid chromatography. Two types of syrups, tablets, and prolonged-release capsules were chosen as tested medicinal products. Although high performance liquid chromatography was the most time and money-consuming, it gave the truest results. In contrast, both UV spectrometric determinations were the least costly and time-consuming, but the calibration line method was the least true and the standard addition method was the least precise. Key words: ambroxol, UV spectrometry, high-performance liquid chromatography
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The influence of the surface pretreatment of boron doped diamond electrodes on electrochemical oxidation of phenol and its derivatives
Hnízdilová, Lucie ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this thesis is the study of electrochemical oxidation of para-substituted phenol derivates using cyclic voltammetry (CV) and ,,direct current" voltammetry (DCV) on boron-doped diamond electrode (BDD) and comparison with some analogous meta-substituted compounds. Among the studied substances were p-cresol, 4-methoxyphenol, 4-hydroxybenzoic acid, 3-(4-hydroxyphenyl)propionic acid, 4-nitrophenol, 4-chlorophenol and 3-(trifluoromethyl)phenol. The oxidation of the analytes was performed in an acidic (pH 2,0) and basic (pH 11,0) Britton-Robinson buffer on mechanically polished, oxidated and hydrogenated surfaces. Another subject of the thesis is to analyze the influence of different substituents, characterized by the Hammett constant, on the oxidation potential of selected phenols. They are oxidized at more positive redox potentials in acidic media, than in basic media, where they are dissociated. The oxidation on the polished and hydrogenated surfaces were similar, whereas were shifted to higher values on the oxidated surface. Further, the signal intensity decreased on the oxidated one, and the oxidation of phenols was not recognizable in basic media. The passivation of the electrode was less significant in pH 2,0 buffer. The best result of Hammett correlation was achieved on a polished and...
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Analysis of the degradation products of the active substances in historical pharmaceutical relicts from 18th and 20th century.
Čambal, Peter ; Nesměrák, Karel (advisor) ; Kubíčková, Anna (referee)
Historical pharmaceutical preparations analyzed in this thesis were a senna extract more than 200 years old, an ointment "Naso-Merfen" 75 years old, and an ointment "Sulfathiazol" 42 years old. The active substances in the analyzed samples were sennosides A and B (senna extract), ephedrine and menthol (the ointment "Naso-Merfen"), and sulfathiazole (the ointment "Sulfathiazol"). The senna extract was analyzed by RP-HPLC and HPLC-MS. Separation conditions were optimized, especially for separation of the sennoside A and B enantiomers. The active substances were not detected in the sample. One degradation product and substances characteristic for senna were identified. Their presence in the historical and contemporary sample was compared. Detailed ESI− -MSn fragmentation mechanisms of sennoside A and B have been proposed. The sample of the ointment "Naso-Merfen" was analyzed by HILIC-UV, HPLC-MS, GC-MS, and AAS. Separation conditions were optimized. The active substances were quantified. Degradation products of the active substances were not detected in the sample. The sample of the ointment "Sulfathiazol" was analyzed by RP-HPLC and HPLC-MS. Separation conditions were optimized. The active substance was quantified. Degradation products of the active substance were not detected. The authenticity of...
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Analysis of the composition and degradation of pharmaceutical substances and pharmaceutical preparations from the 18th and 20th centuries
Kudláček, Karel ; Nesměrák, Karel (advisor) ; Bosáková, Zuzana (referee) ; Gabriel, Jiří (referee)
The dissertation focused on the analysis of twenty historical remains of pharmaceutical substances and pharmaceutical preparations dating to the 18th and 20th century by liquid and gas chromatography with UV-spectrometric or mass spectrometric detection. The analytical approach was chosen with regards to the age and pharmaceutical forms of the analyzed historical remain. The authenticity of the sample was verified by identifying the active ingredients, their possible degradation products and other excipients by tandem mass spectrometry. The fragmentation of some analytes was also studied by tandem mass spectrometry. The stability of historical pharmaceutical preparations from the 20th century was assessed on the basis of a decrease in the concentration of active substances compared to the content declared by the manufacturer or, in case of historical pharmaceutical remains from the 18th century, on the basis of active substance concentrations determined in the historical residue and current reference material. A multi-analytical approach combining five analytical methods, the results of which complement each other, was used to analyze the historical remains of ointments. While the active substances identified in ipecacuanha were found to be partially degraded, they were completely degraded in senna...
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Analysis of Nicotine or Opium Alkaloids in Historical Pharmaceutical Relics from 18th Century
Belianský, Michal ; Nesměrák, Karel (advisor) ; Kubíčková, Anna (referee)
Belianský M.: Analysis of Nicotine or Opium Alkaloids in Historical Pharmaceutical Relics from 18th Century. Bachelor Thesis. Prague, Charles University, Faculty of Science 2020. Abstract: Two samples of historical relics of pharmaceuticals dated to the 18th century were analyzed; the first sample contained tobacco, the second laudanum, i.e., a preparation containing opium. HPLC with UV or mass detection was used for analysis. Separation of the alkaloids was performed on X Bridge® BEH C18 column using binary gradient elution. By comparison with a modern tobacco sample and on the basis of data from the literature, the presence of nicotine degradation products, especially 6-hydroxy-N-methylmyosmine, was found in the historical sample. Because the nicotine content in the historical sample was very low, it was not possible to quantify it. The analysis of opium analytes in the second historical relics revealed the main opium alkaloids (cotarnine, morphine, meconin, papaverine, and noscapine) as well as their degradation products. Main alkaloids were also quantified. The ratio of noscapine to cotarnine was determined, which according to the literature is an indicator of the age of opium pharmaceuticals. Key words: degradation, HPLC, mass spectrometry, nicotine alkaloids, opium alkaloids
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Voltammetric Determination of 7-Dehydrocholesterol as a Biomarker of Smith-Lemli-Opitz Syndrom
Zárybnická, Adéla ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this thesis was the development of a voltammetric method for the determination of 7-dehydrocholesterol as a biomarker of congenital disease Smith-Lemli-Opitz syndrome. The concentration of 7-dehydrocholesterol in plasma will increase hundred-fold to hundreds to thousands µmol L-1 in patients suffering from Smith-Lemli-Opitz syndrome. The determination of 7-dehydrocholesterol was carried out in artifical serum in this work, which was prepared to mimic the conditions of postnatal diagnosis of Smith-Lemli-Opitz syndrome. 7-dehydrocholestrol provides a well developed voltammetric signal at approximately +0.8 V vs. Ag/AgNO3 in acetonitrile. Differential pulse voltammetry with optimized parameters was used for the determination of 7-dehydrocholesterol. The presence of protein in artificial serum (human serum albumin) resulted in an unacceptably high detection limit of the method (178 µmol L-1 in artificial serum). Therefore, human serum albumin was eliminated from the artificial serum samples by precipitating it with acetonitrile and subsequently centrifuging the resulting suspension. At the same time, the ratio of aqueous and organic components in the studied medium was also adjusted with acetonitrile to achieve an optimal voltammetric response of 7-dehydrocholestrol. With regard to the...
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