National Repository of Grey Literature 16 records found  previous11 - 16  jump to record: Search took 0.02 seconds. 
Electrochemical Study of the Supported Iron Oxide Catalysts
Gál, M. ; Horváth, B. ; Navrátil, Tomáš
Propylene oxide (PO) belongs to the group of the most important chemical industrial\nintermediates. It is mainly used for polyurethanes, pharmaceuticals, textile, and detergent\nproduction. In this short contribution we tried to characterize supported iron(III) oxide\ncatalyst with different amount of Fe and to find an optimal iron(III) oxide content for the best\ncatalysts performance. The importance of phase quality on the selectivity of respective\ncatalysts samples is also discussed. Linear sweep voltammetry was chosen for this purpose.\nResults obtained by electrochemical methods are compared with efficiency (selectivity) of\nrespective catalysts.
Electrochemical Measurements in Flow Systems on Silver Amalgam Tubular Detector Combined with Auxiliary Electrode
Josypčuk, Bohdan ; Barek, J. ; Josypčuk, Oksana
A new type of tubular detector (TD+AuxE) was proposed, fabricated, tested and compared\nwith a typical silver amalgam tubular detector developed earlier. Non-stop-flow differential\npulse voltammetric anodic stripping method (AS-DPV) and amperometric method in a\nglucose oxidase biosensor arrangement were tested. Both detectors were applied for AS-DPV\nmeasurements in flow systems for the first time. The proposed combination of tubular\ndetector with auxiliary electrode provides a much greater current response than the classic\narrangement with three individual electrodes. All relevant parameters (potentials of\naccumulation or detection, flow rate, analyte concentrations, shielding sleeve length, etc.)\nwere optimized for the developed TD+AuxE.
Supported Liquid Membranes for Hollow-Fibre Based Microextraction and Voltammetric Determination of Neuroblastoma Biomarkers
Hrdlička, Vojtěch ; Barek, J. ; Navrátil, Tomáš
Novel method of three phase hollow fibre based liquid/liquid/liquid microextraction coupled\nwith voltammetric determination of clinical biomarkers homovanillic and vanillylmandelic\nacid is being developed. Wide variety of water-immiscible supported liquid membranes\n(SLMs) were tested. Highest enrichment factors were obtained using butyl benzoate as SLM.\nEnrichment factors for 30 min HF-LPME were 3. 0.74 for HVA and 5. 0.45 for VMA,\nrespectively. Repeatability of HF-LPME of microM HVA or VMA was 19.0% for HVA and\n7.9 % for VMA (n=5), respectively.
Influence of Fungicide Thiram on Chlorophyll Content and on the Growth of Garden Strawberry (Fragaria Annanasa)
Jakl, M. ; Jaklová Dytrtová, Jana ; Navrátil, Tomáš ; Marková, A.
Thiram is a relatively frequently used fungicide in agriculture and gardening. However, its behavior in environmental systems has not been elucidated in detail up to now. The effect of thiram presence in three different soil types on the yield and chlorophyll contents in garden strawberry plantation was investigated. It is possible to conclude that its presence in soil significantly increased the chlorophyll a and b contents in slightly acidic soil from Humpolec location. The changes of investigated parameters could be ascribed to supported mobilization of Mg, acting together with other nutrients mobilized in low pH of soils. The yield decreased addition in all tested soil types under thiram application.
Electrochemical biosensors with flow-through enzymatic reactors
Josypčuk, Oksana ; Josypčuk, Bohdan
Twelve enzymatic biosensors with various silica powder reactors were fabricated and tested.\nExperiments with six silica materials showed that mesoporous silica SBA-15 was the best one\nin terms of covering by enzymes, sensitivity and lifetime of biosensors. The current response\nof the SBA15-glucose oxidase (GOx) sensor started to decrease only after 200-day testing.\nThe used amalgam tubular detector in a flow system allowed working at highly negative\npotentials. Statistical results of parallel measurements of model solutions with the fabricated\nbiosensors show their high accuracy and sensitivity. The proposed SBA15-GOx biosensor\nwas used for determination of glucose in commercial honey.
Determination of 5-hydroxyindole-3-acetic acid using Flow Injection Analysis with Electrochemical Detection
Makrlíková, Anna ; Matysik, F.-M. ; Navrátil, Tomáš ; Barek, J. ; Vyskočil, V.
Tumour biomarker, 5-hydroxyindole-3-acetic acid, has been determined at screen-printed carbon electrodes using flow injection analysis with amperometric detection. Britton-Robinson buffer (0.04 mol-l-1 , pH 2.0) was used as an optimum carrier solution.\nDependence of the peak current on the analyte concentration was linear in the whole tested\nconcentration range (from 0.5 to 100 mikromol-l-1) with limits of detection 0.033 mikromol-l-1 \n(calculated from peak heighst) and 0.012 mikromol-l-1 (calculated from peak areas).

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