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Arsenic determination in beer samples and raw materials for its preparation
Švadlenová, Veronika ; Hraníček, Jakub (advisor) ; Jelínek, Ivan (referee)
This thesis describes the optimization of the method for determination of arsenic by the chemical hydride generation coupled with AAS detection in beer samples and raw materials for its preparation. The beer usually contain arsenic at ultratrace level, however, it is necessary to monitor the concentration of this element in the beer. The routinely used method for determination of arsenic is determination by electrothermal atomization. This approach is time consuming, expensive and less sensitive. It has been developer suitable determination of arsenic as a faster and less expensive method. For this method there was optimized the flow rate of argon to 75 ml·min-1, the optimum flow rate for the reagents was 4.0 ml·min-1 and for the sample 5.0 ml·min-1 . 3 % NaBH4 in 0.5 % NaOH was used as the reducing agent for the determination of arsenic, and HCl diluted 1:1 with distilled water was used to acidify the sample. With this parameter LOD was 0.32 μg·l-1 and LOQ 1.05 μg·l-1 . It has been tested the arsenic determination in samples of barley, malt and potable water as beer raw materials. It has been found that the beer matrix is unsuitable for the hydride generation technique due to a stormy reaction in the gas/liquid phase separator. The effect of pretreatment, which is likely to enhance the effect of...
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Anthropogenic pollutioin of the Elbe River sediments
Haismanová, Pavla ; Chalupová, Dagmar (advisor) ; Bernsteinová, Jana (referee)
The thesis focuses on contamination of sediments in fluvial lakes of the Elbe river. The research was conducted in Kluk Lake near Poděbrady which has been artificially isolated from the river and its connection to the Elbe is now limited. The thesis concentrates on chemical composition of old sediments in vertical profile which documents an old anthropogenic pollution of Elbe's floodplain. The individual layers of sediment were analyzed separately. Besides grain size, the research also determined concentration of heavy metals and arsenic (Ag, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn). The sediment samples taken near the river contained higher content of elements compared to the more distant sampling site. This finding points out to the various distribution of elements and different settling velocity in the lake. Application of the geoaccumulation index showed that the sediments were very strongly polluted by silver and moderately to strongly polluted by arsenic, cadmium, mercury, lead and zinc. Last, the sediments were unpolluted to moderately polluted by cobalt, chromium, copper, manganese and nickel. According to the methodology of the International Commission for the Protection of the Elbe River (MKOL), the concentrations of silver, mercury, nickel and lead exceeded the upper limit value. Finally,...
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Speciation analysis of inorganic arsenic in seafood material
Pokorná, Nikola ; Matoušek, Tomáš (advisor) ; Musil, Stanislav (referee)
This thesis was focused on extraction of individual arsenic species from reference materials of fish protein DORM-3 and DORM-4. Extracts were then analyzed by a hydride generation method with detection by inductively coupled plasma mass spectrometry. Materials were extracted in two ways - in a microwave device and in a heating block. It was found that extraction with 2% nitric acid is not efficient. Extraction performed in 2% nitric acid with addition of hydrogen peroxide at various concentrations increased the extraction yield, but it caused conversion of arsenic species. This conversion would mean the overestimation of inorganic arsenic content.
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Microdomains in freshwater sediment as a driving factor in the biogeochemical processes
Duchoslav, Vojtěch ; Falteisek, Lukáš (advisor) ; Beranová, Jana (referee)
A natural arsenic anomaly at Mokrsko is a site of biogenic precipitation of realgar (As4S4) in stream sediment. The extent of the phenomenon in Mokrsko is globally unique. A previous study showed the ability of microorganisms to solubilize arsenic from its secondary minerals and to produce realgar precursors, i.e. sulfides and arsenites, by anaerobic respiration. The study also raised questions about the mechanism of realgar precipitation since physicochemical conditions favoring this reaction were never detected despite significant sampling efforts. We chemically and microbiologically analyzed sedimentary profiles to the depth of ca. 120 cm in order to understand the functioning of the biogeochemical system. The profiles comprised both the unsaturated and the saturated zone. We distinguished six different domains representing environments from the surface soil to anoxic sedimnent containing realgar-encrusted wood. An analysis of phylogenetic dissimilarity revealed that microbial communities from the various domains form distinct clusters. This suggests that different conditions prevail in the various domains, and that different biogeochemical processes take place there. Incubation (microcosm) experiments showed that bioprecipitation of realgar can be conducted in vitro. It requires a suppression...
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Trace and minor elements in coal and methods of their investigation
Páchová, Helena ; Opluštil, Stanislav (advisor) ; Sýkorová, Ivana (referee)
The aim of the bachelor thesis is to provide an overview of the minor and trace elements in coal matter and to characterize their origin, distribution and effect on quality of coal in term of its industrial utilization, including potential environmental impacts. The thesis describes main methods currently used when investigating coal geochemistry and mineralogy. The thesis includes overview of the distribution of these elements in the major coal deposits of the Czech Republic.
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Preconcentration of hydride forming elements in quartz trap in connection with ICP-MS
Kašpar, Miroslav ; Matoušek, Tomáš (advisor) ; Rychlovský, Petr (referee)
Charles Uviversity in Prague Faculty of Science Department of Analytical Chemistry Student: Miroslav Kašpar Supervisor: RNDr. Tomáš Matoušek, Ph.D. Name of Thesis: Preconcentration of hydride forming elements in quartz trap with ICP-MS detection The aim of this thesis are pilot experiments employing quartz trap (QT) for preconcentration of hydride forming elements and their subsequent detection by inductively coupled plasma mass spectrometry (HG-QT-ICP-MS). Arsenic and antimony were chosen as model analytes. Preconcentration efficiency on quartz surface was studied in a trap, which was integrated into an interface between spray chamber and plasma torch. We have identified a critical loss of analyte during transportation, instability of the plasma due to sudden change of gas composition, poor repeatability and very quick release of Sb from the trap resulting in difficult quantification of Sb signal. Despite the efforts to resolve these experimental problems, so far we were unable to achieve improvements in analytical parameters compared to standard analytical methods. Keywords: Preconcentration, quartz trap, mass spectrometry with inductively coupled plasma, hydride generation, arsenic, antimony
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Trace speciation analysis of arsenic in beverages
Fajgarová, Aneta ; Matoušek, Tomáš (advisor) ; Spěváčková, Věra (referee)
The aim of this bachelor thesis was to determine the toxicologically important arsenic species in beverages (beer, wine and apple juice) with minimal sample preparation. Determination of arsenic species was performed by selective hydride generation of arsenic hydrides with cryogenic collection under liquid nitrogen and detection by atomic absorption spectrometry. In all the samples only inorganic arsenic was found, methyl substituted species were below the limit of detection. The method is suitable for speciation analysis of arsenic in beverages. Detection limits are low enough, the determination is not influenced by the sample matrix. The results were also in good agreement with the determination of total arsenic after mineralization by ICP-MS. Since there is no specified maximum arsenic content in beverages, measured concentrations were compared with the limit for drinking water (10 μg l−1 ). All samples were under this limit, except for one sample of apple juice, which arsenic content was about twice higher. Key words speciation analysis, atomic absorption spektrometry, hydride generation, arsenic, beverages
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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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Treatment of mine waters rich in arsenic
Řáhová, Jaroslava ; Drahota, Petr (advisor) ; Kindlová, Helena (referee)
Summary: This bachalor thesis deals with treatment of mine waters rich in arsenic. First part is an overview of decontamination methods used for elimination of arsenic from water. Emphasised parts are focused on arsenic adsorption on Fe-oxides and hydroxides, particles which may be formed in mine waters; as well as on ODAS treatment system, widely used for mine waters decontamination. The experimental part is a study of decontamination process at mine treatment plant waters in Kaňk, Kutná hora. Extremely high concentrations of arsenic (77,72 mg/L) are found in acid mine drainage from closed Turkaňk mine. Results of this thesis signifies incorporation of arsenic and other elements dissolved in mine water into secondary forming Fe-oxyhydroxides within decontamination process.
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