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The study of PET bottles in terms of the content of risk elements
Kryštofová, Petra ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This bachelor thesis deals with the issue of PET bottles in terms of the possible content of risk elements. The contents of antimony, copper and lead were determined in the PET packaging material and in the beverages contained in the bottles. A total of 15 samples of bottled still and infant water available in the Czech sales network were analyzed. The PET material was decomposed in an acidic medium under the action of microwave radiation under optimized conditions. Atomic absorption spectrometric methods with flame or graphite cuvette atomization were used to determine selected risk elements based on the predicted analyte concentrations. In the PET packaging material, 159.35 to 265.68 mgkg-1 of antimony were determined, the determined values of lead concentration were in the range of 10.96-20.23 mg·kg-1 and the copper concentration in the range of 0.11-7,52 mg·kg-1. In bottled water and in bottled infant water, antimony was identified only in samples labeled 6a, 8a, 9a and 15a, all lead concentrations were measured below LODPb, copper was determined only in samples 2a, 6a and 8a. In none of the samples did the concentrations given by the valid legislation be exceeded. The limits of these metals are not set in legislation in the packaging materials, only specific migration limits and they have not been exceeded. However, the high concentration of antimony in PET poses a potential risk of contamination of the contents of these packages.
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Effect of lead and antimony on the degradation of graphite shape in cast iron
Hlobil, Albert ; Kaňa, Václav (referee) ; Záděra, Antonín (advisor)
The bachelor thesis focuses on the effect of lead and antimony on the degradation of graphite in cast iron in relation to the lowered mechanical characteristics. This leads to the subsequent summary of the formation of degraded structures and unfavourable elements – the elements that are the cause of the formation. In the practical segment of the thesis, I will prove the effects of lead (or the combination of lead and antimony) on the degradation of graphite in cast iron with the focus lying at flake graphite. Furthermore, the thesis examines the mechanical characteristics and the attenuation of cast iron in relation to the formation of degraded graphite structures.
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Multicomponental Preconcentration of As, Sb, Se and Te on Modified Silica, Their Determination by ICP-AES (ICP-MS) and Application for Waters
Urbánková, Kristýna ; Řehůřková, Irena (referee) ; Kanický, Viktor (referee) ; Ventura, Karel (referee) ; Sommer, Lumír (advisor)
The determination of inorganic speciations of arsenic, antimony, selenium and tellurium in natural waters demands often separation and preconcentration. Solid phase extraction is a very effective method for these purposes. In this paper the separation and preconcentration of these microelements is realised on the basis of modified silica Separon SGX C18, SGX C8, SGX CN, SGX NH2, SGX Phenyl and strongly basic anion Exchanger SGX AX. The sorption was provided in the presence of cationic surfactants such as benzyldimethyl dodecylammonium bromide (Ajatin), benzyldimethyltetradecylammonium chloride (Zephyramine), 1-ethoxycarbonylpentadecyltrimetrhylammonium bromide (Septonex) and selected complexing agents 4-(2-pyridylazo)resorcinol (PAR), 8-hydroxyquinoline-5-sulphonic acide (8-HQS), 1,2-dihydroxybenzene (PYR), amonium 1-pyrrolidinecarbodithioate (APDC), sodium diethyldithiocarbamate (DTC) or thiourea(Thur). The interactions of the formed ion associate with the sorbent shows a complicated character which has not been cleared as yet. The previous conditioning of the sorbent plays an outstanding role. Thus, the sorption efficiency was studied in the presence and absence of surfactant and of selected organic complexing agents. Moreover, the influence of pH of the sorbed solution as well as the speed and the volume of the solution running through the sorbent and the type and volume of the eluent on the resulting sorption efficiency was evaluated. The sorption was successfully carried out from 50-1000 ml of solution which allows the 100 fold increase of the preconcentration factor and the determination of the microelements in g.l-1 instead of mg.l-1 by using the common ICP-AES. The influence of macroelements occurring in waters as well as B, Be, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sr, Ti, V and Zn in comparable concentrations involve less than 5% error. After the quantitative elution of microelements, the organic solvents were evaporated under IR lamps prior to the determination by ICP-AES and |ICP-MS. The conditions for the direct determination of arsenic, antimony, selenium and tellurium in g.l-1 with ICP-MS were also described in detail in the absence and presence of internal standards Ge and Bi. However, even in this case the preconcentration on silica in the presence of surfactant and selected organic complexants was also tested. When the sorption was followed from 500 ml a 50 fold enrichment factor is reached and the sensitivity for the microelements is improved. The direct determination and the sorption of microelements were applied on synthetic and real waters (dirinking, surface, mineral and sea waters). Instrumental and practical detection limits for various water samples were evaluated according to IUPAC. The results from 1000 ml solution of real waters after sorption on modified silica and the final determination of microelements with ICP-AES were compared with those from ICP-MS without sorption using the method of standards addition in the presence of suitable internal standards. By comparison of results for synthetic and real water samples the error of the determination of microelements was evaluated.
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Investigation of Miniature Devices for Collection of Hydride Forming Elements in Atomic Spectrometry Methods
Krejčí, Pavel ; Čelechovská, Olga (referee) ; Janoš, Pavel (referee) ; Otruba, Vítězslav (referee) ; Dočekal, Bohumil (advisor)
Capability of a prototype of miniature collection device based on a strip of the molybdenum foil for collecting hydride forming elements (As, Se, Sb and Bi) was studied. The device was combined with a miniature hydrogen diffusion flame for detection by atomic absorption spectrometry. The conditions for trapping and subsequent vaporization of analytes of interest were optimized. A twin-channel hydride generation system was used for study of mutual interference effects of co-generated hydride forming elements. The influence of modification of the molybdenum surface with noble metals - Rh, Pt and Ir on trapping and vaporization processes was also studied and changes of microstructure of the foil surface after modification were investigated using scanning electron microscope equipped with energy dispersive x-ray analyzer and electron backscattered diffraction system. Complementary radiotracer and radiography experiments were performed in order to determine trapping efficiency and to assess the spatial distribution of collected analytes within the device. Practical application of the method was demonstrated on determination of antimony in water samples at trace level. Possibility of multi-element analysis was demonstrated by combining the collection device with atomization and excitation of the analyte in microwave induced plasma and with detection by atomic emission spectrometry method. The results of the experiments proved that tested miniature collection device is capable of trapping analytes that form volatile hydrides. This device can be coupled to various types of atomizers, typically used in spectrometry methods. Thus, very sensitive and specific detection of hydride forming elements can be performed.
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Study of Generation, Trapping and Atomization of Hydride Forming Elements for Atomic Spectrometry
Furdíková, Zuzana ; Sommer, Lumír (referee) ; Čelechovská, Olga (referee) ; Řehůřková, Irena (referee) ; Dočekalová, Hana (advisor)
Interference effects of co-generated hydrides of arsenic, antimony, bismuth and selenium on trapping behavior of selenium or antimony hydrides (analytes) within iridium modified, transversely heated graphite tube atomizer (THGA) was investigated. A twin-channel hydride generation system was used for independent separate generation and introduction of analyte and interferent hydrides, i.e. in simultaneous and/or sequential analyte-interferent and interferent-analyte mode of operation. Influence of the analyte and modifier mass, interferent amount, trapping temperature and composition of the gaseous phase was studied. A simple approach for elimination of mutual interference effects by modification of the gaseous phase with oxygen in substoichiometric ratio to chemically generated hydrogen is proposed and suppression of these interference effects is demonstrated. A hypothesis on mechanism of trapping and mutual interference effects is drawn.
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Printed transparent oxide conductors
Bartoš, Radim ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
Thin films of tin oxide doped by fluorine or antimony were prepared by spincoating technique and material printing technique. Plenty of inorganic and organic coumpouds were used as precursors of fluorine and antimony. Sheet resistence of films were measured by 4-probe method and film thickness were determined by contact profilometer. Films were analyzed by Xray diffraction (XRD) and scan electron microscopy (SEM).
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Fabrication and characterization of oxidic conductive layers
Bartoš, Radim ; Gemeiner,, Pavol (referee) ; Dzik, Petr (advisor)
Liquid composition for antimony doped tin oxide solgel deposition was prepared. Anorganic precursors of tin and antimony were used (tin(IV) chloride, antimony(III) chloride). ATO nanoparticles were dispergated in composition. This composition was used for spincoating deposition of thin films. Composition was analyzed by thermal analysis TGA and DSC. Sheet resistence of prepared samples were examined by four probe sensing. RMS roughness and thickness was measured by profilometry. Samples were analyzed by scan electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Transmittance and haze were measured and calculated by UV-VIS spektrometry with integration sphere.
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The effect of selected compounds on determination of antimony by atomic fluorescence spectrometry with UV-photochemical generation of volatile compounds
Jelínková, Klára ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
5 Abstract This bachelor thesis is focused on the investigation of the influence of selected chemical individuals on the determination of antimony by UV-photochemical generation of volatile compounds with atomic fluorescence spectrometry detection (UV-PVG-AFS). Antimony, as a toxic semimetal occurring mainly in the trivalent and pentavalent oxidation state, plays an important role in many industries. Its determination is of importance not only from the point of view of analytical chemistry but also for monitoring of its environmental effects and for human health. For the interference studies with Sb5+ , the inorganic ions Br− , Cr2O7 2− , I− , CO3 2− , K+ , Cr3+ , Cd2+ , Co2+ , Cu2+ , Ni2+ , Na+ , Zn2+ , the organic solvents acetonitrile, ethanol and methanol, as well as the extraction reagents L-cysteine and 2-mercaptoethanol were chosen. Br− , Cr2O7 2− , I− , CO3 2− , K+ , Cr3+ , Cd2+ , Na+ and Zn2+ were chosen as possible interferents in the determination of Sb3+ . Solutions of the interferents were prepared in a medium of acetic acid (35%v/v) and 50 g l−1 Sb3+ or Sb5+ . The detection limit of the determination of Sb3+ in the flow injection mode analysis was 3.7 g l−1 for peak area and 1.9 g l−1 for peak height evaluation. For Sb5+ determination, the detection limit was 3.6 g l−1 for peak area and...
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Compatibility of determination of antimony by UV-photochemical generation of volatile compounds and atomic fluorescence spectrometry with potential matrix components
Klečková, Adéla ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
The root of this bachelor work is UV-photochemical generation (UV-PVG) of volatile substances of antimony. Problematics, with which we deal, are potential interferences, which can affect measurement. As model interferents when considering future speciation analysis of antimony using HPLC-UV-PVG-AFS were chosen acetonitrile, methanol, ethanol, L-cysteine and 2-mercaptoethanol. Detection was progressed using atomic fluorescence spectrometry (AFS). L-cysteine muffled the response. Methanol and ethanol were behaving alike. They were increasing and lowering the peaks in waves, when only at the highest concentration they completely disappeared. Acetonitrile was proved to be the most interesting one thanks to its specifical behaviour, which started to show off in higher concentration. 2-mercaptoethanol had in smaller amount similar interference properties as acetonitrile.
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Research on the content of risk elements in the material of PET bottles
Kryštofová, Petra ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This thesis deals with the research of the content of risk elements in the material of rPET (recycled polyethylene terephthalate), supplied from various countries, and the study of different factors (type of liquid, temperature) on the migration of antimony from this material. The recycling process has the potential to increase the content of unwanted substances and promote the formation of degradation products of chemical additives and by-products of polymerization, thus contributing to higher migration of these substances into food or food simulants [1]. The supplied rPET samples were subjected to total decomposition in an environment of concentrated sulfuric and nitric acid under the influence of microwave radiation prior to analysis. Prepared samples were analyzed by atomic absorption spectroscopy (AAS) techniques. The contents of Sb and Zn were determined by flame atomic absorption spectrometry (FAAS), and the concentrations of Pb, Cu, Zn, Cd, Cr, and Ni were determined by electrothermal atomic absorption spectrometry (ETAAS). Additionally, the concentrations of Sb were determined by this method in migration experiments. This thesis builds upon the author's bachelor's thesis, which included pilot experiments.
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