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Optimization of a Flow Rate for a Hyphenation of Voltammetry with Electrospray Ionization Mass Spectrometry
Jaklová Dytrtová, Jana ; Jakl, M. ; Norková, Renáta ; Navrátil, Tomáš
The hyphenation of an electrochemical cell prior to mass spectrometer with electrospray ionization allows studying of products and/or of intermediates of electrode reactions. The measurement is realized in a flowing system. The flow rate of the sample markedly influences the MS signal intensity of the product. The calculated optimum value for the electrochemical cell with the sweep volume 0.72 μL is in the range from 0.4 to 0.5 mL h -1 . The experimental optimal value is 0.45 mL h -1 . The optimization of the flow rate has to be provided individually for each product, because the intensity also depends on the rate of the electrode reaction and product stability.
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(Strept)avidin-biotin interactions at amalgam electrodes covered by thiol monolayer
Josypčuk, Bohdan ; Mareček, Vladimír ; Yosypchuk, O.
Carboxylic group of 11-mercaptoundecanoic acid (MUA) can be used to creat a peptide bond with species containing amino group, e.g., peptides, and proteins. By the help of EDC-NHS technology, streptavidin or avidin was covalently bonded with MUA-monolayer at a silver solid amalgam electrode. Such prepared electrode was used for detecting biotin and biotinylated albumin in the supporting electrolyte (0.15 M NaCl, 0.05 M TRIS, pH 7.0). Electrochemical impendance spectroscopy was performed for the biosensor response monitored by impedance spectroscopy. Binding of biotin or biotinylated albumin with (strept)avidin a change in the resistance of the sensor in the concentration range of 0.5-20 μg mL-1. Electrochemical regeneration of the amalgam electrode permits simply to renew its surface and to create the new biosensor.
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Assessment of Potential Risk Connected with the Use of Mercury and Mercury Electrodes
Navrátil, Tomáš ; Švancara, I. ; Mrázová, K. ; Nováková, Kateřina ; Chýlková, J. ; Pelclová, D.
This contribution tries to asses critically the danger connected with utilization of mercury in different branches of human activites. The main attention was devoted to electrochemistry, mainly to voltammetry and polarography. However, to other branches were characterized as well: dentistry, in battery production, mining industry, and a few others. The most toxic and contarily almost nontoxic forms of mercury and of its compounds were characterized. Some interesting cases of exposure to mercury, according to the database of the Czech Toxicological Information Centre (TIC) (from years 1995-2011), have been reported,
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Use of Copper Solid Amalgam Electrode for Determination of Triazolic Fungicide Tebuvonazole
Nováková, Kateřina ; Navrátil, Tomáš ; Jaklová Dytrtová, Jana ; Chýlková, J.
With the use newly developed mercury meniscus-modified copper solid amalgam electrode (inner diamter 1.5 mm), the voltammetric behavior of fungicide tebuconazole was researched by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Applying CV and elimination voltammetry with linear scan (EVLS), the reaction mechanism was investigated. The optimum conditions for DPV determination of this triazolic fungucude were identified in Britton-Robinson buffer/methanol (1:1, v/v) of pH 6.3 DPV with optimized parameters (Ein = +400 mV vs. Ag/AgCl/3M KCl, scan rate 20 mV s-1) was used for determination of determination of tebuconazole in analyzed solutions. Application the prolonged time (60 s), the limit of detection 2.10-7 molL-1. The applicability of the developed method was verified on the analysis of the real soil solution sample.
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Investigation of Complexes of Tebuconazole with Zinc
Jakl, M. ; Norková, Renáta ; Navrátil, Tomáš ; Jaklová Dytrtová, Jana ; Balík, J.
Tebuconazole is one of the most utilized triazole pesticides in agriculture. Its stability is highly affected by complexation with metals. Moreover, it creates more or less stable complexes with essential elements that become unavailable to plants. In the system with overbundant tebuconazole, an inert (very stable) complex with Zn was found. Elimination voltammetry wit linear scan was used for revealing of the electrode processes on the mercury surface. The relatively slow kinetically controlled step in tebuconazole/Zn complex formation indication indicates the great ability of Zn-tebuconazole system to react with more ligans. Therefore, multiligand Zn-tebuconazole complexes with other ligands are expected in the nature.
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Artificial phospholipid membranes as models of real membranes and transport of charged particles across them
Parisová, Martina ; Navrátil, Tomáš ; Šestáková, Ivana ; Kohlíková, E. ; Petr, M.
Because the real bio-membranes and the tranporting processes realized across them are very complicated, the model membranes have been used for elucidation of the basic transporting steps. In the contribution, the different possibilities of characterization, description, and elucidation of the transport processes on the example of some metal ions and theor complexes, i.e., of cadmium, lead, and copper, were presented. It summarizes the results achieved using supported phospholipid model membranes formed on porous membranes and on agar support. Discussed transporting processes of selected ions have been characterized using two electrochemical methods: electrochemical impendance spectrometry (EIS) and voltammetry. The impact of some parameters on these systems and processes was investigated.
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Voltammetric determination of anticancer drug flutamide at screen-printed carbon electrodes
Vyskočil, V. ; Navrátil, Tomáš ; Barek, J.
Flutamide, 4-nitro-3-trifluoromethyl-isobutylanilide, is the active component of a synthetic nonsteroidal antiandrogen drug, which is commonly used in the treatment of advanced prostate cancer. In this contribution, optimum conditions have been found vor voltammetric determination of flutamide by DC voltammetry (DCV) and differential pulse voltammetry (DPV) at screen-printed carbon electrodes (SPCEs). Under optimum conditions (Britton-Robinson buffer pH 7.0 - methanol (9:1)), linear calibration curves were measure with limits of quantification 6x10(-7) molL(-1) and 8x10(-7) molL(-1) for DCV at SPCEs, respectively. The newly developed methods were successfully applied to the determination of the drug in pharmaceutical formulation Apo-Flutamide (Eulexin tablets).
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