|
|
Determination of Lithium in Mineral Waters Using Electrophoresis in Short Capillary.
Makrlíková, Anna ; Opekar, František (advisor) ; Tůma, Petr (referee)
The aim of this study was determination of lithium ion concentration in mineral waters "Vincentka" and "Bílinská kyselka" using capillary electrophoresis with contactless conductivity detection. A specialized laboratory-made apparatus designed for separations in short capillaries was first tested for separation of model solution of common inorganic cations and then for analysis of mineral water samples. Lithium ion concentration was determined using method of standard addition. The results obtained were compared with those obtained from atomic absorption and emission spectroscopy; standard addition method as well as the method of calibration graph were used in spectroscopic methods. A good agreement was obtained between experimentally determined concentrations of lithium and those declared in the labels on the mineral water bottles. Keywords Capillary electrophoresis, contactless conductivity detection, mineral waters, lithium, atomic absorption spectroscopy, atomic emission spectroscopy
|
|
|
Electrophoretic determination of saccharides in flower nectar
Hurychová, Nikola ; Křížek, Tomáš (advisor) ; Sobotníková, Jana (referee)
This work deals with the development and basic validation of a method for determination of sucrose, glucose and fructose content in floral nectar. It uses capillary zone electrophoresis with contactless conductivity detection. The theoretical part describes the functions of carbohydrates in nectar, principles of capillary zone electrophoresis and contactless conductivity detection. There is also a brief overview of applications in the determination of carbohydrates. In the experimental part, sample injection at the short and at the long end of capillary were tested. In further experiments, the background electrolyte was optimized. The tested concetrations of NaOH were from 10 to 50 mmol l-1 . Optimal conditions for the experiments were injection at the short end of the capillary, 40mmol l-1 NaOH as background electrolyte and separation voltage of 15 kV. Then, the repeatability, limit of detection and quantification and recovery of the method with a real sample of nectar were verified. Lactose was used as an internal standard. Relative standard deviation was below 2 %. Limits of detection were below 0.003 mg ml-1 and limits of quantification were below 0.009 mg ml-1 . Recovery of the method was 97-105 %. Furthermore, the calibration dependences were measured, from which the concentration of...
|
|
|
Changes in the background electrolyte caused by electrolysis in capillary zone electrophoresis
Novotný, Tomáš ; Gaš, Bohuslav (advisor) ; Křížek, Tomáš (referee)
4 Abstract Electrode reactions are one of the inevitable side effects which occur during standard separation measurement on capillary zone electrophoresis. Electrolytic products arising from the electrolysis of water, which is the main procces occuring at the electrodes in the majority of cases, can cause changes in background electrolyte located in vials and inside the separation capillary. The precision and reproducibility of the separation experiments is decreased due to the degradation of background electrolyte in capillary zone electrophoresis. Changes in the background electrolyte are highly dependent on the composition of the buffer itself: some electrolytes are changed more than the others within the same configuration of the experiment. A correct choice of the buffer with the right manipulation of the background electrolyte leads to higher precision and reproducibility of the separation measurements. Keywords: Capillary zone electrophoresis, electrolysis, background electrolyte, contactless conductivity detection
|
|
| |
|
|
Determination of enzyme activity of cellobiase using capillary electrophoresis
Velvarská, Romana ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
This thesis deals with optimization of capillary electrophoresis conditions for the separation of unreacted substrate and products (cellobiose, glucose) generated by the enzymatic cleavage of cellotriose with enzyme cellobiase. The optimal separation electrolyte was shown to be a solution containing 30 mmol·dm-3 sodium hydroxide with addition of 1.0 mmol·dm-3 sodium phosphate and 1.0 mmol·dm-3 sodium phosphate dibasic (pH = 12.38). With this separation electrolyte calibration curves and repeatability were measured and the limits of detection and quantification were determined. The relative standard deviations of peak areas ranged up to 6.1 % and they did not exceed 0.2 % for the migration time. Limits of detection were determined in the range from 0.020 to 0.026 mmol·dm-3 and limits of quantification from 0.066 mmol·dm-3 to 0.085 mmol·dm-3 . Subsequently the enzyme reaction was monitored in offline setup. Furthermore, the offline procedure was automated and the relative standard deviation of cellodextrines after 30 minutes of hydrolysis was ranging up to 13.0 % of glucose and cellotriose and 3.0 % cellobiose using this automated method, which makes it suitable for semiquantitative and comparative measurements. The last part of the experiment was to carry out enzymatic reaction in online setup....
|
|
|
Comparison of contactless conductivity detection and direct UV detection sensitivity for electrophoretic determination of N-acetylaminosaccharides
Malý, Michal ; Křížek, Tomáš (advisor) ; Kozlík, Petr (referee)
is work deals with development and optimization of a method for separation and detection of N- acetylglucosamine and its dimer and trimer using capillary zone electrophoresis with contactless conductiv- ity detection. Separation and detection of these substances is possible if sodium hydroxide is used as back- ground electrolyte. Usage of another electrolyte such as disodium phosphate leads to unacceptable baseline noise level. Optimal conditions of this method are a background electrolyte concentration of 40 mmol dm−3 and voltage of 15 kV. e method is very sensitive to background electrolyte pH, used background electrolyte also causes rapid degradation of the inner capillary wall which is why this method has proven difficult to cali- brate properly. e developed method was compared to an already existing method which uses UV detection. e existing method has lower limits of detection and quantification and is less sensitive to working condi- tions. Limits of detection and quantification of the developed method are 34 µmol dm−3 and 104 µmol dm−3 respectively. Limits of detection and quantification of the method based on UV detection are 7 µmol dm−3 and 21 µmol dm−3 respectively. Limits of quantification are that of the analyte whose detection was the least sensitive which was the dimer in both...
|
|
|
Determination of Lithium in Mineral Waters Using Electrophoresis in Short Capillary.
Makrlíková, Anna ; Opekar, František (advisor) ; Tůma, Petr (referee)
The aim of this study was determination of lithium ion concentration in mineral waters "Vincentka" and "Bílinská kyselka" using capillary electrophoresis with contactless conductivity detection. A specialized laboratory-made apparatus designed for separations in short capillaries was first tested for separation of model solution of common inorganic cations and then for analysis of mineral water samples. Lithium ion concentration was determined using method of standard addition. The results obtained were compared with those obtained from atomic absorption and emission spectroscopy; standard addition method as well as the method of calibration graph were used in spectroscopic methods. A good agreement was obtained between experimentally determined concentrations of lithium and those declared in the labels on the mineral water bottles. Keywords Capillary electrophoresis, contactless conductivity detection, mineral waters, lithium, atomic absorption spectroscopy, atomic emission spectroscopy
|
|
|
High-fast electrophoretic determinations of clinically important compounds in body fluids.
Málková, Klára ; Kvasnicová, Vladimíra (referee) ; Bosáková, Zuzana (advisor)
A capillary electrophoretic procedure employing contactless conductivity detection (C4 D) has been developed for direct determination of the glycerol and mannitol polyalcohols in biological and pharmacological samples. Both glycerol and mannitol are fully separated from the sample matrix within very short times of 3.0 and 3.9 min., respectively, when using the optimized background electrolyte, 60 mM H3BO3 + 30 mM LiOH (pH 9.1). The limits of detection amount to 0.5 µM for glycerol and 0.3 µM for mannitol. The repeatability of the glycerol determination in real biological materials is characterized by the coefficient of variation values, 0.5 % and 3.2 %, for the migration time and the peak area, respectively. The procedure has been used to monitor the free glycerol concentration in adipose tissue microdialyzates. A physiological study has demonstrated that the lipolysis occurring during a sporting action can be stimulated by local application of adrenaline. The procedure has further been utilized to determine mannitol in a pharmacological preparation.
|
guest ::
