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Voltammetric Determination of 5-Nitrobenzimidazole Using Non-Traditional Electrode Materials
Chládková, Barbora ; Vyskočil, Vlastimil (advisor) ; Zima, Jiří (referee)
5 Abstract This Diploma Thesis is targeted on the determination of 5-nitrobenzimidazole (5-NBIA) using following techniques: DC voltammetry (DCV) and differential pulse voltammetry (DPV). As working electrodes, a silver amalgam paste electrode (AgA-PE), which was constructed for this determination in the form of a new prototype, a bismuth film electrode (BiFE), at which the optimum conditions for the deposition of the bismuth film at a suitable substrate (glassy carbon electrode and gold electrode were tested for this purpose) were initially optimized, and a glassy carbon electrode (GCE) were used. The optimum conditions for the voltammetric determination of 5-NBIA at the AgA-PE (in a medium of Britton-Robinson buffer (BR-buffer) of pH 7.0 for both DCV and DPV), at the BiFE with gold substrate (BR-buffer of pH 9.0 for both DCV and DPV; the film was deposited "ex situ" in a stirred plating solution (1000 mg L-1 Bi(III) solution in 0.1 mol L-1 acetate buffer of pH 4.5) for 300 s), and at the GCE (BR-buffer of pH 5,0 for both DCV and DPV). Under these conditions, calibration dependences were measured in the concentration ranges of 0.1 - 100 µmol L-1 (pro DCV a DPV na AgA-PE) and 1 - 100 µmol L-1 (pro DCV a DPV na BiFE a GCE), and the limits of quantification (LQs) were calculated for particular methods: LQ ≈...
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The use of carbon-based electrodes for the development of new electrochemical methods for the determination of aminonitrophenols
Dejmková, Hana ; Zima, Jiří (advisor) ; Ludvík, Jiří (referee) ; Vytřas, Karel (referee)
4 ABSTRACT Methods for the determination of five isomers of aminonitrophenol were developed, based on the technique of differential pulse voltammetry (DPV) and HPLC with amperometric detection. As the working electrodes, boron-doped diamond film electrode (BDDFE) and glassy carvon paste electrode (GCPE) were employed. Preliminary electrode testing was performed by cyclic voltammetry. The methods were aimed to the determination of all five aminonitrophenol isomers in hair dyes and to the determination of 2-amino-4- nitrophenol and 4-amino-2-nitrophenol in body fluids after solid phase extraction. From the voltammetric methods, the one using BDDFE for the cathodic determination in hair dyes exhibits sufficient selectivity. The performance of chromatographic methods was found suitable for the determination of aminonitrophenols in both observed matrices. The applicability of the developed methods was successfully confirmed by the determination of tested analyted in real samples of hair dyes and spiked samples of urine. Preceding measurements are described, dealing with the determination of other oxidizable compounds, containing phenolic or aniline moieties on BDDFE. The obtained results confirm that in some cases, BDDFE shows more resistance to fouling than other carbon-based electrodes, but in most cases, the...
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Determination of vanillin using carbon paste electrode
Jarošová, Romana ; Zima, Jiří (advisor) ; Daňhel, Aleš (referee)
Title: Determination of vanillin using carbon paste electrode. Abstract: The aim of this work is the determination of vanillin by flow injection analysis (FIA) with electrochemical detection using carbon paste electrode (CPE) and spectrophotometric detection. Optimal conditions for determination of vanillin by the FIA were found. Under optimal conditions calibration dependences were measured in the concentraction range from 1·10-4 mol·l-1 to 2·10-7 mol·l-1 . The calibration dependences were evaluated using linear regression method. Comparable results were achieved for the determination of vanillin by FIA with electrochemical detection using CPE and for the determination of vanillin by FIA with spectrophotometric detection. Limits of detection were identical 1.7·10-7 mol·l-1 . Key words: vanillin, carbon paste electrode, flow injection analysis, electrochemical detection, spectrophotometric detection
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Determination of benzophenone derivatives using carbon paste electrodes
Fähnrichová, Barbora ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
The proposed Thesis is dealing with the determination of 2,4-dihydroxybenzophenone (BP-1) and 2-hydroxy-4-methoxybenzophenone (BP-3) using HPLC with electrochemical and UV spectrophotometric detection. For separation of studied substances column Kromasil 100-7 μm, C18, 150 x 4,6 mm was used. As working electrodes in case of electrochemical detection carbon paste and glassy carbon electrodes were used. UV spectrophotometric detection was running at 288 nm. The method of determination was optimized, then used to measure calibration dependences for both substances, which were used for calculating limits of detection. Further, this method was used for the determination of studied substances in urine where preconcentration of BP-1 and BP-3 using solid phase extraction was used. In addition to this method of sample preparation, the possibility of direct determination of the analytes in urine with the addition of sodium dodecyl sulfate to the mobile phase was tested. Key Words: 2,4-dihydroxybenzophenone 2-hydroxy-4-methoxybenzophenone carbon paste electrode UV spectrophotometric detection HPLC with electrochemical detection
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