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Electrochemical generation of tellurium hydride for AAS
Resslerová, Tina ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
Tellurium is non-biological element which is not common in the earth. It can be accumulated in a body and cause many health problems. In this work, tellurium is determined by the electrochemical hydride generation technique coupled with atomic absorption spectrometry with quartz tube atomizer. In the first part of this work, various relevant parameters of tellurium hydride generation were optimized to achieve high sensitivity. Under the optimal working parameters, calibration dependences and other basic characteristics were measured. Finally, the influence of oxygen added on the different places of set up was carried out. Optimized parameters were flow rate of the carrier gas, generation current, flow rate and concentration of electrolytes. Optimizations were measured for two different catholytes: hydrochloric and sulfuric acid, with similar results. In addition the calibration was measured with orthophosporic acid. Further experiments with oxygen were performed for sulfuric acid as the catholyte. Influence of oxygen on the baseline and the process of determination were performed, for both continuous and limited time addition.
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Sensitivity increasing of gold determination by electrochemical volatile species generation with AAS detection
Vacek, Tomáš ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
This thesis is focused on increasing the senstitivity of gold determination by electrochemical volatile species generation using two different types of electrolytic cells in continuous flow setting. Externally heated quartz tube atomizer was used as means of atomization and detection of gold with atomic absorption spectrometer. Generation parameters were optimized for electrolytic cell with an ion exchange (nafion) membrane. After selection of new cathode material (Cu) the carrier gas (Ar) flow rate was optimized, where an additional inlet of carrier gas was found to have possitive effect on increasing the sensitivity of determination of gold and efficiency of volatile specie transport to the atomizer. Experiments with Antifoam B showed possitive effect on generation, thus calibration was carried out for optimized experimetal conditions reaching detection limit of 0,53 mg.dm−3 . The efficiency of volatile specie transfer from liquid to gaseous phase was determined between 60 - 65 % by measuring the residual gold content in liquid waste by F-AAS method. Subsequently the effieciency of electrolytic generation of volatile gold specie with radioactive tracer isotopes and autoradigraphy was determined to 0,6 %. These methods confirmed adsorption of generated species on apparatus surface. Using ICP-MS as...
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Electrochemical generation of tellurium hydride for AAS
Resslerová, Tina ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
Tellurium is non-biological element which is not common in the earth. It can be accumulated in a body and cause many health problems. In this work, tellurium is determined by the electrochemical hydride generation technique coupled with atomic absorption spectrometry with quartz tube atomizer. In the first part of this work, various relevant parameters of tellurium hydride generation were optimized to achieve high sensitivity. Under the optimal working parameters, calibration dependences and other basic characteristics were measured. Finally, the influence of oxygen added on the different places of set up was carried out. Optimized parameters were flow rate of the carrier gas, generation current, flow rate and concentration of electrolytes. Optimizations were measured for two different catholytes: hydrochloric and sulfuric acid, with similar results. In addition the calibration was measured with orthophosporic acid. Further experiments with oxygen were performed for sulfuric acid as the catholyte. Influence of oxygen on the baseline and the process of determination were performed, for both continuous and limited time addition.
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