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Digestion methods for speciation analysis of toxicologically important forms of arsenic in tissue by hydride generation with cryotrapping and atomic absorption spectrometry
Taurková, Petra ; Rychlovský, Petr (advisor) ; Spěváčková, Věra (referee)
This diploma thesis develops methodology of arsenic speciation analysis by selective hydride generation with cryotrapping and atomic absorption spectrometry. Using this technique it is possible to determine toxicologically important forms of arsenic, i.e arsenites, arsenates and their mono-, di-, and trimethylated forms at concentration levels below 0,1 ng.ml-1 . The first part of the thesis is focused on testing tubular membrane gas dryers with nafion membrane for drying gaseous phase containing generated hydrides. The suitability for arsenic speciation analysis was investigated and transport losses of individual arsenic species were found. The second part describes mild digestion procedures suitable for arsenic speciation analysis in tissues. Two procedures were compared, acid digestion in phosphoric acid and more recent alkalic digestion by tetramethylammonium hydroxide. Digestion procedures were tested on certified reference material DOLT - 4 (Dogfish Liver) and chicken liver matrix. Key words: Tubular nafion membrane dryers, Arsenic speciation analysis, Digestion, Phosphoric acid, Tetramethylammonium hydroxide, Chicken liver, CRM DOLT - 4, Hydride generation, Atomic absorption spectrometry
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Kinetic determination of nitrites with spectrophotometric detection
Vašíčková, Pavla ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
Title: Kinetic determination of nitrites with spectrophotometric detection Annotation: The proposal and optimization of the kinetic determination of nitrites in water samples is the aim of this bachelor thesis. The method is based on the ability of nitrites to catalyze the oxidation of toluidine blue by bromate in acidic media. The course of the reaction is monitored by spectrophotometrically, using a decrease of the absorbance band at 653 nm in the constant period of time from the beginning of the reaction. The dual-chanel manifolds FIA apparatus was proposed and optimized. The calibration dependency in the range of 0,05-1,00 mg ml-1 was measured. The instrumental limit of detection of 0,038 mg ml-1 and limit of quantification of 0,125 mg ml-1 were calculated. The method was applied on real sample of river water. Key words: nitrites, flow-injection analysis, kinetic catalytic methods
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Laser Ablation of FOX-7: Proposed Mechanism of Decomposition
Civiš, Martin ; Rychlovský, Petr (referee)
A novel high-energy explosive material, FOX-7 (1,1-diamino-2,2-dinitroethylene), was studied using a combination of laser-induced breakdown spectroscopy (LIBS) and selected ion flow tube mass spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (an ArF excimer laser) as the energy source to convert small quantities of a sample into plasma and to induce the emission of its molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three reagent ions, with the ability to determine concentrations of trace gases and vapors of volatile organic compounds in real time. SIFT-MS was used to study the release of NO, NO2, HCN, HONO, HCHO, CH3CH2OH, and C2H2 after laser ablation of the explosive compound FOX-7 in solid crystalline form. The radiation emitted after excitation was analyzed using a time-resolved UV-vis spectrometerwith an ICCDdetector.The electronic bands ofCN(388nm),OH(308.4 nm), andNO(237.1 nm) radicals and the atomic lines of C, N, and H were identified.
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Determination of Lead Using FIA Technique with Spectrophotometric and Electrochemical Detection
Hála, Petr ; Vyskočil, Vlastimil (advisor) ; Rychlovský, Petr (referee)
The aim of this thesis was the determination of lead in water samples using complexating reaction with 4-(2-pyridylazo)-resorcinol in medium of 2-amino-2- hydroxymethyl-propan-1,3-diol hydrochloride buffer (Tris·HCl). Firstly, for the determination was chosen UV/VIS molecular spectrometry in a static arrangement. Subsequently, the method was performed in flow injection arrangement. The calibration was performed under optimal experimental conditions. The limits of detection for static and flow injection arrangements were 0.097 mol dm-3 and 0.27 mol dm-3 , respectively. Secondly, the determination of lead by differential pulse voltammetry was performed. The electrochemical properties of lead complex were investigated. During these experiments it was found out that small amount of this complex was adsorbed on the surface of silver solid amalgam electrode. The calibration was performed, the limit of detection was 0.020 mol dm-3 . Keywords Lead, 4-(2-pyridylazo)-resorcinol, flow injection analysis, UV/VIS molecular spectrometry, differential pulse voltammetry, silver solid amalgam electrode.
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Determination of dissociation exponents of selected polyaza derivatives
Hajduová, Jana ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
Title: Determination of dissociation exponents of selected polyaza derivatives Annotation: The aim of this thesis is extimation of dissociation exponets of seclected polyaza derivatives by acid-base titration with potentiometric registration of titration curve. The titration curve was processed using Hyperquad 2006 software. The satisfactory agreement of determined values of dissociation exponents with literature data was found. Key words: dissociation exponent, potentiometric titration, polyaza compounds
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