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Electrochemical sensor with electrode modified by phthalocyanine derivative used for determination of sulfur compounds
Zlámalová, Magda ; Nesměrák, Karel (advisor) ; Navrátil, Tomáš (referee)
The diploma thesis presents the results of the studies of thin layer film composed of N,N',N'',N'''-tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt. This film is deposited on the surface of highly oriented pyrolytic graphite. The modified electrode displayed electrocatalytic activity to oxidation of sulphide anions and cysteine. It has been studied the possibility of enhancement of stability of the immobilized film by the nafion. This electrode was used for the analytical determination of sulphide anions and cysteine. Keywords: highly oriented pyrolytic graphite, porphyrazines, hydrogen sulphide, cysteine, nafion, cyclic voltammetry, atomic force microscopy
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Testing of Polished Silver Solid Amalgam Composite Electrode for Voltammetric Determination of Environmental Pollutants
Dědík, Jan ; Vyskočil, Vlastimil (advisor) ; Nesměrák, Karel (referee)
The aim of this study was the finding of applicable conditions for the determination of selected model environmental pollutants, namely 5-nitrobenzimidazole and picric acid, using DC voltammetry (DCV) and differential pulse voltammetry (DPV) at a polished silver solid amalgam composite electrode (p-AgSAE-CE) in the aqueous solution of Britton-Robinson (BR) and finding of the limit of quantification (LQ) for these substances. For 5-nitrobenzimidazole, the optimum conditions of voltammetric determination have been found in the medium of B-R buffer pH 5, but any calibration dependences were obtained. The reason was the deteriorating quality of 5-nitrobenzimidazole response even if the routine pretreatment of working electrode was maintained. This resulted in obtaining of irreproducible results upon the determination of 5-nitrobenzimidazole. For picric acid, the optimum conditions have been found for both DPV and DCV at p-AgSAE-CE in the medium of B-R buffer pH 2. The concentration dependences were measured in the range 1.10-6 - 1.10-4 mol.L-1 for DPV with the value of reached LQ 2,5.10-7 mol.L-1 and, for DCV, in the range 1.10-7 - 1.10-4 mol.L-1 with LQ calculated as 5,5.10-8 mol.L-1 . For comparison of newly developed voltammetric methods of picric acid determination, a UV-VIS spectrophotometric...
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The Flow Injection Analysis of Procaine and Sulfamethoxazole with Spectrophotometric Detection
Baptistová, Adéla ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
A derivatization reaction, based on a copulation reaction of diazonium salt of an analyte with a reagent (1-aminonaphthalene or NEDA) producing colour, spectrophotometrically detectable product, has been used for determination of two analytes (procain hydrochloride, sulfamethoxazole) containing amino group in the molecule. The conditions of batch spectrophotometric determination were studied. It was found, that the batch determination is applicable only for procain hydrochloride analysis, because sulfamethoxazole gives time-unstable colour product. FIA arrangement was proposed and effects of selected parameters were optimized using two levels factorial design. The calibration dependences were measured for both analysis with both reagents, and subsequently were applied on determination of analytes in medical forms. Key words: diazotization, flow injection analysis, procaine, spectrophotometry, sulfamethoxazole
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Comparision of methods for sulphide determination
Zlámalová, Magda ; Nesměrák, Karel (advisor) ; Červený, Václav (referee)
The aim of this work is determination of sulphides in a solution by suitable methods and it's subsequent comparison from a point of view to the precision, financial and time demands. Iodometric titration, argentometric titration, and potassium ferricyanide titration were chosen for the determination of sulphides in the solution. Anhydrous sodium sulphide and sodium sulphide hydrate were used as model samples. From the point of view to financial and time demands the most advantageous method was potassium ferricyanide titration and the least advantageous method was iodometric titration. The precision of used methods was dependent on type of used sample. Iodometry was the least precise determination of sulphides in the sample of anhydrous sodium sulphide; the precision of argentometry and potassium ferricyanide titration was comparable. Potassium ferricyanide titration was the most precise determination of sulphides in the sample of sodium sulfide hydrate; the least precise determination was argentometry.
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Study of Factors Influencing the Teduction of Rhenistane
Burešová, Helena ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
The aim of the bachelor thesis was to study the influence of conditions on the reduction of ammonium perrhenate by selected reduction agents. The amount of reduced perrhenate was followed by differential pulse voltammetry (as the decrease of the height of DPV peak). The percentage of reduced perrhenate was expressed as a function of molar ratio of the reduction agent to perrhenate. The following four agents were employed: sodium borohydride, hydroxylamine hydrochloride, hydrazine hydrochloride, and ascorbic acid. An amount of 97.8% of rhenium reduced was achieved by 0.9-fold of molar excess of sodium borohydride in 2 mol dm-3 perchlorid acid. The threefold molar excess of hydroxylamine hydrochloride reduced rhenium by 85% (in medium with pH = 8.5). The threefold molar excess of hydazine hydrochloride reduced rhenium by 68% (in medium with pH = 5.0). Ascorbic acid was the last studied reduction agent; its threefold molar excess reduced rhenium by 98.7%.
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