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Determination of zinc in food supplements
Nedorostová, Helena ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
- 1 - Abstrakt Tato bakalářská práce je zaměřena na stanovení zinku (zinečnatých iontů) v potravinových doplňcích pomocí atomové absorpční spektrometrie. Součástí práce je také porovnání mezí detekce dvou odlišných atomových spektrometrů. Cílem práce bylo zjistit optimální podmínky a vliv interferencí na stanovení zinku, nalézt vhodnou metodu pro převedení vzorku do roztoku, a také porovnat meze detekce u použitých přístrojů. Optimalizovanými parametry byla výška paprsku nad hranou hořáku, průtoková rychlost acetylenu, otočení hořáku, šířka spektrálního intervalu, typ plamene. Převedení pevného vzorku do roztoku bylo provedeno ve vodě za laboratorní i zvýšené teploty, v kyselině dusičné nebo kyselině dusičné s přídavkem peroxidu vodíku, též za zvýšené teploty. Analyzovány byly tyto potravinové doplňky: Centrum od A až po železo, Walmark- vápník, hořčík, zinek, Spektrum 50+, Calibrum 50 plus, Supradyn Energy Complex. Množství zinku v potravinových doplňcích bylo stanoveno na spektrometru GBC 933 AA v kolmém uspořádání. K porovnání meze detekce byly použity přístroje GBC 933 AA s výbojkou s dutou katodou a ContrAA 700 s xenonovou výbojkou. U obou přístrojů byl pro experiment použit plamen obsahující acetylen-vzduch. Pro stanovení zinku byla pomocí standardních roztoků vytvořena kalibrační křivka, z níž byly...
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Comparison of selenium extraction efficiency from food supplements
Molnárová, Lucia ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
The aim of this bachelor thesis was comparison of selenium extraction efficiency from food supplements which contain various declared forms of selenium. The method of atomic absorption spectrometry with flame atomization was used to determine the efficiency of the extraction. The first step for the determination of selenium in four real samples was the experimental finding of optimal conditions for selenium determination by flame AAS technique. Optimized parameters included the flame composition, the fuel flow rate, the angle of burner rotation, the horizontal burner position and the spectral range. During the testing the flame composition, higher responses were measured by using air as an oxidant, and therefore acetylene-air flame was used to other optimize and measure real samples. After optimization of the conditions, the calibration dependence was determined and the basic characteristics of the measurements were calculated. The detection limit and determination repeatability, sensitivity and operating range were determined for selenium determination. The detection limit was 0.12 mg dm-3 . The real samples of the food supplement tablets were mechanically homogenized and transferred to aqueous solutions, which were subsequently analyzed by the optimal conditions. The highest extraction efficiency...
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Determination of Te(IV) by photochemical generation of volatile compounds with atomic spectrometric detection
Ruxová, Helena ; Hraníček, Jakub (advisor) ; Šíma, Jan (referee)
This thesis deals with the development of a method suitable for determination Te(IV) by UV-photochemical generation of volatile compounds (UV-PVG) in liquid samples. Atomic absorption spectrometry (AAS) and atomic fluorescent spectrometry (AFS) were used as detection methods. The basis of the apparatus for UV-PVG was a mercury lamp wrapped by PTFE capillary. Firstly, the experimental parameters were optimized for both methods. The optimized parameters were the type, concentration, pH and flow rate of the reaction medium, the length of the PTFE reaction coil, carrier gas flow rate (argon), supportive gas flow rate (hydrogen) and atomization temperature. The figures of merit with both detection methods were determined and compared after the method was optimized. Detection limits achieved for these two detection methods were 6,0 µg dm-3 for AFS and 1,50 µg dm-3 for AAS. Performed interference study confirmed a significant effect of many cations of transition metals and hydride forming elements on tellurium determination. The influence of nitric acid in the sample was studied separately. The suitability of the method for tellurium determination was confirmed by using a spiked certified reference material.
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Influence of interfering elements on the electrochemical antimony hydride generation
Vacek, Tomáš ; Hraníček, Jakub (advisor) ; Rychlovský, Petr (referee)
This thesis is focused on the study of different interfering elements during antimony electrochemical hydride generation. Interferences were studied for electrochemical hydride generation with electrolytic cell and also for chemical hydride generation using sodium tetrahydroborate as a reduction agent. The study included the comparison with oxygen influences. Hydride-forming elements (selenium and arsenic), transition metals (zinc, copper and nickel), different anions (chlorides, sulfates and nitrates) and sodium were tested as interferents. The most serious interferents were hydride-forming elements and nickel, where 100 % signal supression was observed in high interferent concentrations. As opposed to sodium and nickel, where almost none signal supression was observed at all concentrations. Keywords Interferences, electrochemical hydride generation, atomic absorption spectrometry, antimony, electrolytic cell, atomization, hydrides
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Electrochemical generation of tellurium hydride for AAS
Resslerová, Tina ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
Tellurium is non-biological element which is not common in the earth. It can be accumulated in a body and cause many health problems. In this work, tellurium is determined by the electrochemical hydride generation technique coupled with atomic absorption spectrometry with quartz tube atomizer. In the first part of this work, various relevant parameters of tellurium hydride generation were optimized to achieve high sensitivity. Under the optimal working parameters, calibration dependences and other basic characteristics were measured. Finally, the influence of oxygen added on the different places of set up was carried out. Optimized parameters were flow rate of the carrier gas, generation current, flow rate and concentration of electrolytes. Optimizations were measured for two different catholytes: hydrochloric and sulfuric acid, with similar results. In addition the calibration was measured with orthophosporic acid. Further experiments with oxygen were performed for sulfuric acid as the catholyte. Influence of oxygen on the baseline and the process of determination were performed, for both continuous and limited time addition.
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Examination of caesium concentration trends in extracts from cement blocks simulating radioactive waste
Straka, Marek ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
Cement is widely used as a solidification material of low and intermediate level radioactive waste containing caesium before shallow land burial. The aim of this thesis was to extract caesium out of 17 cement samples with 6 different cement binder compositions, by extraction with deionized water, then determine the amount of caesium in the extracts and look for trends in the extract Cs concentrations with various extraction duration. Cement samples, with stable caesium nuclide, were used to simulate retention of caesium in immobilized radioactive waste. Ten extractions from each sample in total were made with time ranging from 2 to 1032 hours. Atomic absorption spectrometry with flame atomization, using acetylene as fuel and air as oxidant, was used for caesium determination. This method was optimized and the addition of KCl serving as ionization buffer for better results was explored and compared. Keywords Atomic absorption spectrometry, flame atomization, caesium, extraction,
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Determination of zinc, cadmium and nickel in leaves by inductively coupled plasma-mass spectrometry
Plodík, Michal ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
Práce je zaměřena na stanovení těžkých kovů (zinku, kadmia a niklu) v listech různých druhů stromů. Vzorky byly odebrány z různých lokalit na území České republiky. Pro analýzu byla použita hmotnostní spektrometrie s indukčně vázaným plazmatem, která je dostatečně citlivá pro předpokládané nízké koncentrace vybraných kovů. Pro stanovení koncentrace byla klíčová příprava vzorků pro mikrovlnný rozklad v koncentrované kyselině dusičné. Naměřené koncentrace sledovaných kovů se lišily nejen mezi lokalitami a jednotlivými rostlinnými druhy, ale také v rámci jedné lokality. Použitá metoda ICP-MS prokázala dostatečnou citlivost i u prvků s přirozeně nízkou koncentrací v životním prostředí, což bylo v této práci kadmium.
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Chemiluminescent determination of vitamin B12 using sequential injection analysis
Doležalová, Veronika ; Hraníček, Jakub (advisor) ; Dian, Juraj (referee)
This bachelor thesis deals to find the optimal conditions for the determination of vitamin B12 by the Sequential Injection Analysis (SIA). The basis of the determination is a chemiluminescence reaction in which luminol is oxidized by hydrogen peroxide under the catalysis of cobalt ions in a basic medium. The intensity of the chemiluminescence radiation was measured using a spectrofluorometric detector and the measured intensities were recorded. Suitable experimental conditions were found experimentally before the actual determination. A total of 4 parameters were optimized, namely, the mass percentage of hydrogen peroxide, the ratio between the dosed cobalt ion sample and the luminol solution, the sample flow rate and the luminol concentration. Under optimized conditions, several solutions of known cobalt ion concentration were measured, from which a calibration dependence of chemiluminescence intensity on cobalt ion concentration could be established. For this determination, the basic characteristics were determined. For the determination of vitamin B12 itself by the SIA technique, it was assumed that the vitamin molecule contains exactly one cobalt atom, which was released from the molecule by the action of UV radiation. At the end of the work, the concentration obtained by the measurement was...
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Development of a UHPLC-MS/MS method for determination of rivaroxaban in rat serum
Plášilová, Denisa ; Kozlík, Petr (advisor) ; Hraníček, Jakub (referee)
This bachelor thesis is focused on development of a specific UHPLC-MS/MS method for the determination of rivaroxaban in rat serum. At first, the setting of the mass spectrometer was optimized. Suitable MRM transitions were found for rivaroxaban and its isotopically labeled internal standard. For rivaroxaban was found the MRM transition 436.1 → 145.05 with optimal energy levels Q1 = -12.0 V; CE = -30.0 V; Q2 = -27.0 V. For rivaroxaban D4 was found the MRM transition 440.1 → 145.0 with optimal energy levels Q1 = -22.0 V; CE = -31.0 V; Q2 = -25.0 V. The ion source setting parameters were as follows: nebulizing gas flow 3 l/min; heating gas flow 10 l/min; interface temperature 300 řC; desolvation temperature 526 řC; DL temperature 250 řC; heat block temperature 400 řC; drying gas flow 10 l/min. The optimal chromatographic method was as follows: A Poroshell 120 SB AQ, 100 × 2.1 mm, 2.6 µm (Agilent) chromatographic column; the mobile phase consisted of acetonitrile with the addition of 0.1% formic acid (A) and distilled water with the addition of 0.1% formic acid (B); flow rate of the mobile phase 0.5 ml/min; gradient elution (time: 0-1-2-3.5-4-6.5 min; A: 20-20-80-80-20-20 % v/v); autosampler temperature 15 řC; column temperature 40 řC; time of analysis 6.5 minutes; injection volume 2 µl. The optimized...
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