National Repository of Grey Literature 25 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Temperature-programed micro-HPLC analysis of fatty acid methyl esters with APCI-MS detection
Vrkoslav, Vladimír ; Rumlová, Barbora ; Cvačka, Josef
HPLC/APCI-MS analysis at microliters-per-minute flow rates was optimized for separation of fatty acid methyl esters (FAMEs). HPLC C18 column with an internal diameter of 0.3 mm and isocratic elution using 99.9 % acetonitrile and 0.1% formic acid were employed. Standard APCI ion source was suitable for detection of FAMEs at 10 μl/min flow rate with the detection limit of micrograms-per-milliliter. APCI-MS spectra with predominant [M + H]+ molecular adducts were observed. The main advantage of micro-flow measurements is the possibility of using a temperature gradient, which significantly reduces retention times of FAMEs with longer aliphatic chain. The significant reduction of solvent consumption is also an important economic and environmental advantage. The positions of double bonds in FAME chains were established using acetonitrile-related adducts and tandem mass spectrometry. The optimized method was applied for analysis of FAMEs in triacylglycerol fraction of black currant seeds oil.
Ambient ionization techniques
Vrkoslav, Vladimír
In the first part of the lecture definition and classification of ambient ionization techniques were described. In the next part the principles of the most important ambient ionization techniques were explained and their use was mentioned.
Development of sensors based on porous silicon
Vrkoslav, Vladimír ; Jelínek, Ivan (advisor) ; Mička, Zdeněk (referee) ; Herynková, Kateřina (referee) ; Volf, Radko (referee)
5 Conclusion PS samples with defined macroporous structure were prepared and they were used as sensing layer in PL chemical sensors' concentration dependence of pL quenching response of standard PS was measured ro,ío*orogical set of linear alcohols in gas and liquid phase. From oU*'""a *tl"l"tion' of quenching sensitivity with dielecnic constant and saturated vapour it""ut" in gas and liquid phases follolrs: r. :r _L^-a io .nnrrolled bv dielectric - PL quancbing response of PS in liquid phase is controlled by streng*r ofmlYta - PL quenching response of PS in gas phase is controlled more by equilibriumconcentrationofanalýeinsideporousmatrix.Dielectric strength of analýe is not so important. PSsurfaceswerefunctionalizedwithcobaltphthalocyanine, polypyrrole, permethyl-6r-heptenoylamino-6I-deoxy B-cyclodextrins' methyl-lO-undeceonate and by oxidation' (The work is focused on using the first three compounds') We performed a measurement of concentration dependence of PL sensor response functionalized PS samples for selected organic species in gas phase' We can conclude that the PL quenching.",pň," was modiťred by functionalization of PS with selected compounds, due to change of surface polarity and molecular recognition. The magnitude of sensor response modification is dependent on kind of anallte' Another...
Development of a tube nebulizer for microflow atmospheric pressure chemical ionization mass spectrometry
Strmeň, Timotej ; Vrkoslav, Vladimír ; Pačes, Ondřej ; Cvačka, Josef
A novel nebulizer for microflow atmospheric pressure chemical ionization mass spectrometry was developed. It consisted of a tube with analyte-transporting fused silica capillary inside. The terminal part of the tube was resistively heated using a coiled resistance wire. Optimal nebulizer parameters and construction setup were investigated to fully demonstrate its versability. Corundum appeared to be a more suitable material than quartz for fabrication of the tube nebulizer. The lowest analyte flow rate investigated was 1.0 mul/min with an excellent signal stability reached.
From conventional to special mass spectrometry imaging applications
Vrkoslav, Vladimír
The use of desorption ionization techniques for the distribution of molecules in both typical and non-standard applications was described.
Targeted analysis of branched-chain faty acid esters by LC/MS
Březinová, Marie ; Kuda, Ondřej (advisor) ; Vrkoslav, Vladimír (referee)
Lipidomics as a part of metabolomics is a fast-growing area of research due to the improvement in analytical techniques. This master thesis is focused on lipid extraction techniques optimization, using liquid liquid extraction and solid phase extraction as pre-separation methods and ultra performance liquid chromatography coupled with mass spectrometry for extraction and subsequent identification of branched-chain fatty acid esters (FAHFA - branched-chain Fatty Acid esters of Hydroxy Fatty Acids). This newly discovered class of lipid molecules is associated with insulin secretion, which could improve whole body and local glucose metabolism, providing potential for diabetes 2 type treatment. Solid phase extraction of biological samples was optimized on columns regarding to sorbent composition using reversed phase columns with modified styrene divinylbenzene polymer or octadecyl-bonded polymer and normal phase columns packed with silica gel. Column Strata SI-1 Silica was the most effective for FAHFA separation from biological samples. Chromatographic separation of FAHFA was performed on UPLC Ultimate 3000 RSLC equipped with Kinetex C18 1,7 µm, 2,1 x 150 mm column using gradient program. UPLC was coupled to QTRAP 5500/SelexION, a hybrid, triple quadrupole, linear ion trap mass spectrometer equipped...
Analysis of products of cardanol metathesis by HPLC-MS/MS method
Flenerová, Zuzana ; Čabala, Radomír (advisor) ; Vrkoslav, Vladimír (referee)
Cardanols are more and more used in the industry of polymers, resins, coatings, friction materials, etc. At right conditions, these lipid-like chemicals can undergo metathesis reaction. The main aim of the diploma thesis is an analysis of products of cardanol metathesis by HPLC-MS/MS. Standard 3,3'-hexadec-8-en-1,16-diyldiphenol, one of the main products of cardanol metathesis, was prepared for quantitative HPLC analysis. The standard was prepared in two steps. The first step was cardanol ethenolysis to give 3-(non-8-enyl)phenol. The second step was self-metathesis of 3-(non-8- enyl)phenol to give 3,3'-hexadec-8-en-1,16-diyldiphenol. The standard was characterised by HPLC/MS, MS/MS, EI-MS, UV/VIS, IR, Raman a NMR spectroscopy. The second part of the thesis is dedicated to the study of a mechanism of double-bond localization method in long chain hydrocarbons by acetonitrile APCI-MS. The formation of adducts [M + 55]+ , which are the key substances of this method, was studied using simple alkene models by MS and MS/MS. At the end, the structure and the mechanism of the formation of adducts [M + 55]+ were suggested. Key words: Cardanol, olefin metathesis, HPLC-MS, double-bond localization, APCI, acetonitrile
HPLC: NEW APPROACH TO THE ANALYSIS OF ALIPHATIC HYDROCARBONES WITH LONG CHAIN
Vít, Martin ; Vrkoslav, Vladimír (advisor) ; Schwarzová, Karolina (referee)
The aim of this diplom thesis was development of the reverse phased high performance liquid chromatography (RP-HPLC) for analysis the aliphatic hydrocarbons with long chain and optimalization of this method. In theoretical part is described occurrence and properties of a hydrocarbons, also used separation methods and detectors - evaporative light scattering detector (ELSD) and matrix assisted laser desorption ionization with time of flight analyzer. In experimental part is described izolation of cuticular hydrocarbons from a fly Neobellieria bullata. It was study experimental conditions of separation and detection izolated hydrocarbons. It was performed deep optimalization of conditions on RP-HPLC - composition of mobile phase, gradient, mobile phase flow rate and column temperature. Method optimalization was done by ELSD. It was used kombination of two solvents to mobile phase - acetonitrile : ethylacetate, mobile phase stream 0,8 ml/min and column temperature 50řC were found as optimal conditions for analytical separation. This method were aplicated for analysis cuticular hydrocarbons from fly specie Neobellieria bullata. During separation were collected fractions and then fractions were determined on MALDI-TOF. It was found 37 aliphatic hydrocarbons which included 25 up to 47 carbons and 0 to 3...
Analysis of cuticular extracts of bumblebees species Bombus terrestris
Tomešová, Lenka ; Valterová, Irena (advisor) ; Vrkoslav, Vladimír (referee)
Chemical substances are transferred between bumblebees of the species Bombus terrestris during their mating behavior. These substances are present mainly on the cuticle. The aim of this thesis was to identify and quantitatify differences in the amount of the compounds among defined groups of bumblebees - mated, non-mated and attempting to mate. Cuticular extracts were obtained by washing of the whole bumblebees bodies in hexane. These extracts were analyzed by using a two-dimensional gas chromatography with the time of fly mass spectrometr (GCxGC-TOF/MS). Cuticular hydrocarbons were identified and semi-quantified. Double bounds locations were determined in heptacosene and nonacosene. Five compounds were differed in the examined groups - β-springene, α-springene, dihydrofarnesyl-oleate, palmityl-palmitate and palmityl- palmitoleate. By comparing of the amount of these compounds differences between defined groups of bumblebees were determined. Analysis of the cutilar extracts showed that mated and non-mated bumblebees can be distinguished. Furthermore, there were statistically significant differences in the amounts of identified compounds in all defined groups of bumblebees. Key words: two-dimensional gas chromatography, Bombus terrestris, cutilar extract

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