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A novel AAS atomizer based on a dielectric barrier plasma discharge
Novák, Petr ; Kratzer, Jan (advisor) ; Kanický, Viktor (referee)
Atomization of arsine in a novel hydride atomizer for atomic absorption spectrometry (HG-AAS) was thoroughly optimized. This plasma atomizer is based on a dielectric barrier discharge (DBD). Sensitivity and detection limit reached 0.48 s ng-1 As and 0.16 ng ml-1 As, respectively, under optimum atomization conditions (Ar discharge using a flow rate of 60 ml min-1 Ar, DBD power 17 W). Analytical figures of merit reached in DBD are comparable to those found in an externally heated quartz tube multiatomizer (MMQTA) that was chosen as a model of conventional approach to hydride atomization in HG-AAS. An extent of interferences (Se, Sb, Bi) during As determination was investigated comparing both MMQTA and DBD atomizers. The later one was found to be more resistant towards interferences. A simple preconcentration of As in a DBD atomizer was reached after oxygen introduction into the Ar plasma in the DBD resulting in analyte retention in the atomizer followed by its volatilization once the oxygen flow is switched off. Preconcentration efficiency of 100 % was reached and detection limit improvement by a factor of ten was achieved (0.01 ng ml-1 As, preconcentration period 300 s).
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Mechanism of atomization of selected hydride forming elements in an externally heated quartz tube atomizer and a dielectric barrier discharge atomizer
Juhászová, Lucie ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Atomization conditions for tin hydride in the planar dielectric barrier discharge (DBD) plasma atomizer were optimized with detection by atomic absorption spectrometry (AAS). The effects of apparatus arrangement such as the shape of a waveform function of the high voltage power supply source, DBD atomizer design as well as presence of a dryer tube filled with NaOH pellets to prevent residual aerosol and moisture transport into the DBD were investigated in detail. The optimal experimental setup consisted of a square wave high voltage power supply source coupled to a DBD with vapor-deposited electrodes in the presence of NaOH dryer upstream the DBD atomizer. Argon was found as the best discharge gas under a flow rate of 120 mL min-1 while the DBD optimum high voltage supply rate was 7 kV. A sensitivity of 0.05 s ng-1 Sn and a limit of detection of 1.1 ng mL-1 Sn were reached under optimized conditions. Optimization of the whole experimental setup resulted in 7-fold improvement of sensitivity compared to the original arrangement consisting of a sinusoidal source coupled to a DBD atomizer with glued electrodes in absence of the dryer. Keywords atomic absorption spectrometry, hydride generation, hydride atomization, quart tube atomizer, dielectric barrier discharge (DBD)
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Spectrometric determination of selected metals in the samples from old ecological burden area
Zurynková, Pavla ; Kratzer, Jan (advisor) ; Spěváčková, Věra (referee)
This bachelor thesis is focused on heavy metals pollution in the Králíky town and its vicinity, located in the Pardubice region. This region was selected because there had been a Tesla factory producing fluorescent lamps. Moreover, there is also a waste disposal of the fluorescent lamps wasters and other dangerous waste located about two kilometers far from the former factory. Soil samples from the waste disposal area as well as river sediment, samples taken in the Tichá Orlice river and the Králický brook have been analyzed Mercury, cadmium, lead, chromium, nickel, copper and arsenic levels in the samples were measured by inductively coupled plasma - mass spectrometry. The total mercury content has also been measured with single-purpose atomic absorption spectrometer AMA-254. An optimization of leaching conditions of the elements was performed prior the analysis of the samples employing certified reference material. High levels of mercury, cadmium, lead, chromium, nickel and copper have been found in the waste disposal area. Regarding the sediment samples the highest levels of pollution have been detected near outfall of the sewage water from the industrial area in the Králíky town (former Tesla factory and recent metal plating industry). The concentration of heavy metals in other sediment...
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Generation of zinc volatile species for determination by atomic spectrometry
Dlouhá, Kateřina ; Nováková, Eliška (advisor) ; Kratzer, Jan (referee)
This diploma thesis deals with the determination of zinc by volatile species generation with detection by atomic absorption or fluorescence spectrometry. Volatile zinc species are generated using hydrochloric acid and sodium borohydride stabilized with sodium hydroxide. Conditions influencing the generation and atomization of volatile species were optimized, namely hydrochloric acid concentration, sodium borohydride concentration, sodium hydroxide concentration, hydrochloric acid flow rate, sample loop volume, reaction coil volume, frit porosity in a gas-liquid separator, argon and hydrogen flow rates, and last, the temperature to which the quartz atomizer is heated. Under the optimal conditions, the detection limit of 33 μg·l−1 and the limit of determination of 110 μg·l−1 were reached. It was found that the addition of various reagents (especially 8-hydroxyquinoline) can increase the generation efficiency. With the addition of 1 % (m/V) 8-hydroxyquinoline to the standard/sample the limit of detection was 4 μg·l−1 and the limit of quantification was 12 μg·l−1 . Using an atomic fluorescence spectrophotometer as the detector, the standard reference material was analyzed and good match with the certified concentration value was found, the certified zinc concentration value in the reference material is...
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HG-AAS with atomization in a dielectric barrier plasma discharge: method optimization and analytical applications
Zurynková, Pavla ; Kratzer, Jan (advisor) ; Kanický, Viktor (referee)
The aim of this diploma thesis was to optimize in detail atomization conditions for antimony hydride in a novel plasma atomizer based on a dielectric barrier discharge (DBD) with atomic absorption spetrometric detection. Argon was found as the best DBD discharge gas employing a flow rate of 50 ml min-1 Ar while the DBD power was optimized at 30 W. Analytical figures of merit including interference study of As, Se and Bi have been subsequently investigated and the results compared to those found in an externally heated quartz tube atomizer (QTA). The limit of detection reached in DBD (0.15 ng ml-1 Sb) is comparable to that observed in QTA (0.14 ng ml-1 Sb). Finally, possibility of stibane preconcentration in a DBD atomizer was studied. Preconcentration efficiency of 102 ± 6 % was found under optimized conditions.
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Spectrometric determination of selected metals in the samples from old ecological burden area
Zurynková, Pavla ; Kratzer, Jan (advisor) ; Spěváčková, Věra (referee)
This bachelor thesis is focused on heavy metals pollution in the Králíky town and its vicinity, located in the Pardubice region. This region was selected because there had been a Tesla factory producing fluorescent lamps. Moreover, there is also a waste disposal of the fluorescent lamps wasters and other dangerous waste located about two kilometers far from the former factory. Soil samples from the waste disposal area as well as river sediment, samples taken in the Tichá Orlice river and the Králický brook have been analyzed Mercury, cadmium, lead, chromium, nickel, copper and arsenic levels in the samples were measured by inductively coupled plasma - mass spectrometry. The total mercury content has also been measured with single-purpose atomic absorption spectrometer AMA-254. An optimization of leaching conditions of the elements was performed prior the analysis of the samples employing certified reference material. High levels of mercury, cadmium, lead, chromium, nickel and copper have been found in the waste disposal area. Regarding the sediment samples the highest levels of pollution have been detected near outfall of the sewage water from the industrial area in the Králíky town (former Tesla factory and recent metal plating industry). The concentration of heavy metals in other sediment...
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Next generation of hydride atomizers based on dielectric barrier plasma discharge
Kráľová, Zuzana ; Kratzer, Jan (advisor) ; Hrdlička, Aleš (referee)
Atomization conditions for selenium and lead hydrides in a dielectric barrier discharge (DBD) plasma atomizer with detection by atomic absorption spectrometry (AAS) were investigated in this work. Two designs of DBD atomizers were studied, the first one with glued electrodes and the second one with sputtered electrodes. The main experimental parameters were optimized, including supplied power and discharge gas (argon) flow rate. Additionally, the effect of several dryers was studied. Analytical figures of merit were determined for both plasma atomizers under the optimized conditions and compared to multiatomizer (MMQTA) as the most common hydride atomizer. The optimum flow rate for selenium determination was 75 cm3 min-1 Ar for both DBD atomizer designs as well as for MMQTA. In case of lead hydride atomization, ideal flow rate of argon was 175 cm3 min-1 for DBD atomizer with glued electrodes and 150 cm3 min-1 with DBD atomizer with sputtered electrodes, while MMQTA required only 100 cm3 min-1 Ar. The optimal power supply for DBD with sputtered electrodes was found significantly lower at 7.3 W for selenium and 13.3 W for lead. A dryer based on nafion membrane was found as the most effective for both analytes studied. Its efficacy was verified by optical emission spectrometry. As for analytical...
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