National Repository of Grey Literature 17 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Portable liquid chromatograph and analyses of hazardous substances
Šesták, Jozef ; Gogaľová, Zuzana ; Kahle, Vladislav ; Lunerová, K.
Progress in technology of microchips, batteries and LEDs in the last two decades enable development of portable instruments which can satisfy the requirements of modern liquid chromatography (LC). Application of portable LC is advantageous if simple and rapid sample treatment procedure followed by a short HPLC run can be executed in the point of sampling. Our research group have developed a concept of portable HPLC based on simple hydraulic scheme and a unique optical detector for simultaneous detection of absorbance and fluorescence of compounds eluted off microcolumn. Considering in-field analysis of hazardous substances, this instrument can be advantageous for analysis of compounds which are difficult to detect and quantify by other contemporary portable instruments utilizing different working principles due to incompatibility with their physico-chemical properties (e. g. microbial toxins).
Multidimensional Liquid Phase Separations
Šesták, Jozef ; Čáslavský, Josef (referee) ; Pulkrabová, Jana (referee) ; Česla, Petr (referee) ; Kahle, Vladislav (advisor)
This dissertation is dedicated to the topic of multidimensional liquid phase separations. This separation techniques are developed for analysis of complex samples containing thermally labile, low volatile or high molecular weight components that can´t be analysed by two-dimensional (2D) gas chromatography. Concepts of peak capacity and orthogonality are explained and various methods of their determination are stated in theoretical part of dissertation. High performance column liquid chromatography (HPLC) and high performance capillary electrophoresis (HPCE) are suggested as the most suitable methods for automated multidimensional liquid phase separations on-line coupled to mass spectrometry. Configuration of simplified miniaturized liquid chromatograph is described in experimental part of this thesis. Original concept of the system has been extended by simple mobile phase gradient generation technique. Correct function was demonstrated on repeatable separation of alkylphenones, peptides, nitroaromatics, and nitroesters. This system has been utilized as a base for a couple of simple two-dimensional separation platforms for HILIC-MALDI-MS analysis of glycans, for separation of peptides based on off-line coupling of isoelectric focusing and capillary liquid chromatography, and finally for on-line IEC×RPLC, RPLC×RPLC, and HILIC×RPLC two-dimensional liquid chromatography. Correct operation of submitted platforms has been proved.
Utilization of fluorimetry for detection of underground water tracers
Pokora, Zdeněk ; Čáslavský, Josef (referee) ; Kahle, Vladislav (advisor)
The thesis studies detection of fluorescein for coloration experiments in surface and underground water. The first part of the work deals with the adsorption of fluorescein on active charcoal from water and desorption by means of different desorption solutions. The results of measurements are used for practice of coloration experiments in karst research. In the second part of thesis it is researched the option of automated record of fluorescence concentration and its detection by means of laser induced fluorescence with confocal microscope.
System for fast analysis of explosives in the enviromnemt
Čapka, Lukáš ; Večeřa, Zbyněk ; Mikuška, Pavel ; Šesták, Jozef ; Kahle, Vladislav
Detection of explosives is the subject of many investigations by law enforcement agents and forensic scientist. The identification and discrimination of evidence taken from crime scenes is a common practice in forensic investigations. The higher demands on simple and fast determination of hazard materials or strange objects are required in connection with worldwide often repeated terrorist activities.
HILIC separation of AETMA-labeled glycans on a wide bore silica-based monolithic capillary column
Šesták, Jozef ; Křenková, Jana ; Moravcová, Dana ; Planeta, Josef ; Kahle, Vladislav
In this contribution, we report the separation of AETMA-labeled glycans on a wide bore (320-μm i. d.) silica-based monolithic capillary column modified by [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide.
ZIC-HILIC monolithic capillary column coupled with MALDI-MS: A tool for glycan analysis
Šesták, Jozef ; Křenková, Jana ; Moravcová, Dana ; Planeta, Josef ; Kahle, Vladislav
In this contribution, we report analysis of glycans enzymatically released from bovine ribonuclease B (RNase B) and human immunoglobulin G (hIgG) combining glycan separation using the synthesized zwitterionic silica-based monolithic capillary column and off-line MALDI-MS detection.
Simple liquid chromatography system for low flow rate gradient separations
Šesták, Jozef ; Kahle, Vladislav
Simple approach to the splitless micro-flow liquid chromatograph construction and functionality of the proposed system were presented.
High pressure modification of the simple automated liquid chromatographic system for splitless nano column gradient separations
Šesták, Jozef ; Kahle, Vladislav
Our simple liquid chromatographic system for splitless gradient nanocolumn separations at backpressure up to 50 bars was modified to run analysis under the pressure up to 300 bars. Programmable syringe pump was equipped with a 250-L high-pressure syringe and mobile phase gradients were created and stored in relatively long capillary. Available linear gradients of volumes from 5 to 50 L traced by uracil are presented. Sample introduction was performed as separate step and real large volume of sample (tens of microliters) could be injected and preconcentrated on-column. Relative standard deviation of retention times and peak areas were received (RSD < 0.3 % and RSD < 5 % respectively).
Silica-based monolithic capillary columns modified to zwitterionic stationary phase for hydrophilic interaction liquid chromatography
Moravcová, Dana ; Planeta, Josef ; Kahle, Vladislav ; Horká, Marie ; Roth, Michal
Zwitterionic monolithic capillary columns intended for isocratic gradient hydrophilic interaction chromatography (HILIC) separations are introduced. Silica-based capillary columns (150 mm x 0.1 mm) were prepared by acidic hydrolysis of tetramethoxysilane in the presence of polyethylene glycol and urea. The modification by a 3-(trimethoxysilyl)propyl methacrylate and then by a zwitterionic [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide to HILIC stationary phase bearing sulfoalkylbetaine groups on its surface followed. Prepared columns were characterized in HILIC separation mode employing mobile phase containing 10% (v/v) of 5 mM ammonium acetate pH = 4.5 in acetonitrile. Comparison with the commercially available ZIC-HILIC® column (Merck SeQuant®) under the same separation conditions using a mixture of aromatic carboxylic acids as a sample was done on the basis of separation efficiency of tested columns as well as retention factors and peak asymmetry of individual solutes.
Differences in fingerprints of biofilm-positive and biofilm-negative Candida strains exploitable for clinical practice
Vykydalová, Marie ; Horká, Marie ; Šalplachta, Jiří ; Růžička, E. ; Kahle, Vladislav
In this study, we have presented differences in fingerprints of Candida parapsilosis and Candida metapsilosis as well as their biofilm-positive and biofilm-negative forms. Fingerprints of yeasts were obtained by sodium dodecyl sulfate polyacrylamide gel electrophoresis, capillary isoelectric focusing, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Samples for analyses were prepared by treatment of yeasts by boiling water or ethanol. Fingerprints of tested yeasts cells have differed in all cases. This knowledge can be used for obtaining rapid and simple method which distinguishes above mentioned yeasts in standard biochemical laboratories.

National Repository of Grey Literature : 17 records found   1 - 10next  jump to record: