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Simultaneous online determination of nitric acid and nitrates in ambient air
Alexa, Lukáš ; Čmelíková, D. ; Cigánková, Hana ; Mikuška, Pavel
The innovated method for the simultaneous online determination of HNO3/NO3- in ambient air was developed. Due to high sensitivity of CLD (LOD = 5.1 nM in water solution, 3 s/n) no preconcentration method is required. The online methods were compared with the results obtained with the offline method based on sampling using filters and dry denuders (DD) covered by 0.5% NaF with subsequent analysis by ion chromatography (model ICS-2100, Dionex, USA) and capillary electrophoresis (model Agilent 7100, Agilent Technologies, USA).
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Simultaneous determination of ultratrace concentration of nitric acid and nitrates in air using chemiluminescent online analysers
Čmelíková, Dorota ; Řezáčová, Veronika (referee) ; Alexa,, Lukáš (advisor)
The diploma thesis is focused on the development, optimization and real use of a continuous flow analyser for online determination of nitric acid and nitrates in air. The principle of analysis is photolytic conversion of nitrate in solution to peroxynitrite with subsequent detection by chemiluminescence reaction with luminol. The main aim of this thesis was to optimize parameters of analyser followed by practical use for analysis of urban air. The detection limit of gaseous nitric acid was 0,13 g·m3, resp. 0,10 g·m3 for nitrates in aerosol. The measured online concentrations were compared with reference offline analysis. The analysis of urban air was realized in two campaigns (September 2022 and February 2023) at Institute of Analytical Chemistry of CAS in Brno. The apparatus was placed in laboratory on the second floor and samples were collected from the window at Veveří street.
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Development and Use of Electrochemical Detector for Analysis of Czech Coal Combustion Products
Sokol, Martin ; Nesměrák, Karel (advisor) ; Vyskočil, Vlastimil (referee)
This work examines an electrochemical determination of mixed nitric and sulphuric acid solution that is formed during calorimetric determination of gross calorific value of coal carried out under the ISO 1928:1995 standard. Knowing the amount of these acids is necessary for calculating net calorific value. The named standard only allows use of volumetric methods which are time-consuming. Conductivity and ion-selective measurements were used here which significantly shortened analysis time. Overall conductivity measurement was taken with a 4-electrode meter while nitric acid was measured with a nitrate ISE by known addition method. Sulphuric acid was then calculated according to actual temperature. This research has defined the calibration relations and temperature effect. Several simulated and real-world samples were analysed and the method was evaluated for a possible use in a future automated analyser.
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An Experimental Assesment of Changes to the Size Distribution of Ammonium Nitrate Under Isothermal Conditioning
Talbot, Nicholas ; Ondráček, Jakub ; Ždímal, Vladimír
Results show that for 50nm ammonium nitrate particles, 70-80% losses were recorded through the evaporation chamber. The least volatile was found to be 200nm particulate at 15°C. Generally, at 25°C the greatest reactions were found as was expected from prior research, however an overall increase in particulate concentration at 100nm for all temperature regimes was surprising. Possible multiple physiochemical transformations during transportation through the evaporator, along with activation of impurities within the water could explain these particle gains. The lack of humidity data, inter- transportation temperature profiling and lateral gas measurements limit the effectiveness of this study.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22013101814592 - PDF
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