National Repository of Grey Literature 174 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Voltammetric detection of 27-hydroxycholesterol on boron-doped diamond electrode
Michnová, Kristýna ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this bachelor thesis was to study the voltammetric behavior of 27-hydroxycholesterol using boron-doped diamond electrode. The influence of several factors on the current response of 27-hydroxycholesterol was investigated: the effect of the supporting electrolyte, concentration of perchloric acid, polarization rate, water content, and pH effect. The study was conducted using cyclic voltammetry in a perchloric acid or sodium perchlorate in acetonitrile. 27-hydroxycholesterol provided a current response in the anodic region with a potential around +1450 mV vs. Ag/0.01 mol l-1 AgNO3 in 1 mol l-1 NaClO4 in acetonitrile in the presence of 0.1 mol l−1 perchloric acid in acetonitrile (water content 0.43 %) and 0.1 mol l−1 sodium perchlorate in acetonitrile. Furthermore, concentration dependence was measured using differential pulse voltammetry resulting in a limit of detection (LOD) of 2.71 μmol l−1 and a limit of quantitation (LOQ) of 9.04 μmol l−1 . It was demonstrated that the direct current voltammetry method does not achieve comparable limit values. Key words 27-hydroxycholesterol, boron-doped diamond electrode, oxidation, oxysterols, voltammetry
Determination of active substances and possible degradation products in a historical sample of Algena from 1981
Bauerová, Markéta ; Nesměrák, Karel (advisor) ; Kozlík, Petr (referee)
The Algena tablet was an over-the-counter drug in the second half of the twentieth century in Czechoslovakia. Algena was mainly used against pain. The tablet contains four active substances: aminophenazone, aprobarbital, phenacetin, and caffeine. The aim of this thesis was to analyse the active substances in the Algena tablet from 1981,determinate theircontent,and possible degradation products.To complete these goals the RP-HPLC method with UV detection had to be involved and optimized.HPLC-MS was used to detect possible degradation products. Separation was performed on the XBridge® BEH C18 column (150×3.0 mm; 2.5 µm), binary elution was used. The first component of the mobile phase was0.1% aqueous solution of acetic acid and the second component was methanol. The determined contents of active substances (decelerated by the manufacturer) were: amino- phenazone 97.0%,aprobarbital89.2%, phenacetin 96.0% and caffeine 93.2%.Degradation products of the active substances were not detected by HPLC with MS detection. Key words: Algena, aminophenazone, aprobarbital, caffeine, degradation, phenacetin, RP-HPLC
Mass Produced Medical Products as an Alternative Source of Reference Materials for Calibration
Zouzalová, Monika ; Nesměrák, Karel (advisor) ; Čabala, Radomír (referee)
This thesis aims to statistically demonstrate whether mass-produced medicinal products can be used as an alternative source of reference materials for calibration in analytical chemistry. These preparations could be a potential alternative in cases where time is of the essence, for example in the clinical investigation of intoxication, if analytically certified reference material is not at hand. One of the most used methods in practice, high-performance liquid chromatography, was chosen as the analytical method. Like mass-produced medicinal products containing the active substances paracetamol and codeine were used, namely Panadol Novum 500 mg, Paramax RAPID 500 mg, Paramax RAPID 1 g, Paralen 500 mg, Codein Slovakofarma 28.72 mg and Talvosilen, which contains both mentioned active substances, namely 500 mg of paracetamol and 30 mg of codeine per tablet. Two different lots were tested for Paramax RAPID 500 mg. Potential sources of error were tested throughout the analytical process, namely weighing, solution preparation, and the measuring device. Each potential source of error was statically tested on two types of stock solutions using analysis of variance and Student's one- sample t-test. It was statistically confirmed that the individually selected processes do not introduce errors in the...
Verification of the authenticity of remains of 18th century medicinal products containing juniper or liquorice
Lener, Tomáš ; Nesměrák, Karel (advisor) ; Kubíčková, Anna (referee)
Three remains of historical pharmaceuticals from 18th century containing juniper (Rob juniperi, Lignum juniperi) or liquorice (Pulvis radicis liquiritiae) were analyzed by HPLC-MS method and their authenticity was verified using a chemotaxonomic approach. Current reference material was the source of chemotaxonomic markers and also a raw material for replication of Rob juniperi according to two period recepies. HPLC-MS method provided good results but wasinsufficienttoanalyzeLignumjuniperi.Therefore,GC-MSmethod wasalsousedto analyzethejunipersamplesand it provided sufficient results to prove the authenticity of both juniper samples. HPLC-MS method identified viridiflorin heptoside for the first time in juniper material, for which as well as for five liquorice markers ESI fragmentation spectra weremeasured and theirpossiblefragmentation mechanismwasproposed.Based on theobtained results, thepreparation ofhistorical samplesfrom the mentioned plants can beconfirmed. Key words: HPLC-MS, GC-MS,Chemotaxonomy, Juniper,Liquorice, Tandemmass spectrometry,Viridiflorin
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...
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
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.
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.
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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