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Construction and comparison of electrochemical cells for lead determination by volatile compounds generation technique
Hillmich, Ondřej ; Hraníček, Jakub (advisor) ; Červený, Václav (referee)
This diploma thesis is focused on the construction of the electrochemical cells for the lead determination using electrochemical generation of volatile compounds connected with the atomic absorption spectrometry as a detection technique. Three different electrochemical cells were constructed: membrane electrochemical cell (MEC), non-membrane electrochemical cell 1 (BEC1) and non-membrane electrochemical cell 2 (BEC2). Experimental conditions were optimized in continuous flow mode with cells BEC1 and BEC2. The optimization include flow rate of carrier gas, composition and concentration of the electrolytic solution, atomization temperature, generation current and voltage applied to the electrode material. A 1.0 mm diameter cadmium wire was used as cathode material and the anode material was composed of platinum wire of 0.5 mm in diameter. Under the optimal experimental conditions, the calibration was constructed and basic characteristics of proposed method were determined for the BEC1 and BEC2 cells: limit of detection, limit of quantification, repeatability, sensitivity, linear dynamic range and correlation factor of linear dynamic range. The cell MEC was found to be unsuitable for the lead determination by the electrochemical generation of volatile compounds. Using the BEC1 cell, the experimental...
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Interference study for lead determination using hydride generation technique coupled with AAS detection
Hillmich, Ondřej ; Hraníček, Jakub (advisor) ; Musil, Stanislav (referee)
This bachelor thesis is focused on the interference study of different elements during lead determination using hydride generation technique. For this method tetrahydroborate was used as a reduction agent and hexacyanoferrate as an oxidant agent which dramatically increases efficiency of plumbane formation. Before interference study, significant experimental conditions were optimized. The optimizations include flow rate of carrier gas (argon), concentrations and flow rates of all reagents (HCl, NaBH4, K3[Fe(CN)6]), atomization temperature and volume of sample loop. Under the optimal experimental conditions, the calibration was constructed and basic characteristics of the method were determined - sensitivity (0.0012 l∙μg-1 ), limit of detection (3.13 μg∙l-1 ). For interference measurement another hydride-forming elements (As, Se, Sb, Sn, Bi, Te), significant transition metals (Fe, Ni, Cu, Zn), alkali metal and alkaline earth metal (Na+ , Ca2+ ) and common anions (Cl- , SO4 2- , NO3 - ) including acetate anions were selected. Acetate anionswas incorporated to the study as a representative organic molecule. Hydride-forming elements, mainly selenium, were found as most serious interferents. E.g. selenium at low concentration increases absorption signal of lead. On the other hand, selenium at high...
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