National Repository of Grey Literature 14 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Elimination Voltammetry with Linear Scan: Advantages and Disadvantages
Navrátil, Tomáš ; Trnková, L. ; Hrdlička, Vojtěch ; Li, X.
Elimination voltammetry with linear scan (EVLS) represents an almost traditional\nmathematical method that helps to obtain additional and detailed information about the recorded\nelectrochemical signals and therefore, to better understand the analyzed systems. Although it\nhas been substantially developed and expanded during its existence of more than a quarter of a\ncentury and has found many areas of application, like any other mathematical and experimental\nmethod, it exhibits several advantages and disadvantages. In this contribution, we summarize\nits strengths, weaknesses, opportunities, as well as threats.\n
Determination of Selected Natural Psychoactive Substances in Organic Matrices at 3D Printed Electrodes
Choińska-Mlynarczyk, Marta ; Šestáková, Ivana ; Navrátil, Tomáš
Psilocybin and its derivative psilocin are popular psychoactive substances both as experimental\ntreatments in clinical trials and as illicit drugs. Their potential ability to influence the human\nbrain entails the need for a fast, inexpensive, selective, and sensitive method of their\ndetermination. The aim of our study was the development of new 3D-printed electrodes which\nfulfill these demands and are useful for medical, toxicological, and forensic purposes.\nSuccessful development allows determining in real matrices (human plasma and dried\nmushrooms) concentrations of the order of 1 μmol dm-3.\n
Manufacture of 3D Printed Microfluidic Channels and Their Characterization by Impedance Spectroscopy and Optical Microscopy Measurements
Štěrba, O. ; Vaněčková, Eva ; Choińska-Mlynarczyk, Marta ; Navrátil, Tomáš ; Kolivoška, Viliam
Fused deposition modeling 3D printing employing high-resolution extrusion nozzles and specialized manufacturing protocols have recently attracted attention as an inexpensive tool to create microfluidic devices. In this work, we have applied such an approach to create measurement cells with integrated microchannels of systematically varied dimensions. The real width of channels was inspected by two techniques, namely (A) impedance spectroscopy employing an aqueous sensing electrolyte and (B) optical microscopic imaging of silicone imprints hardened in the interior of printed structures. Both techniques have demonstrated that fused deposition modeling 3D printing enables precise manufacturing of channels with truly microfluidic dimensions.
Mercury Film Screen-Printed Electrodes
Josypčuk, Bohdan ; Šestáková, Ivana ; Tvorynska, Sofiia
Mercury film screen-printed electrodes (MF-SPEs) were designed, prepared and tested for the first time as perspective representatives among SPEs that allow measuring at high negative potentials. For this purpose, the precise electrochemical (coulometric) preparation procedure for mercury deposition at the working electrode surface of the commercial silver-SPE was developed and a universal method of preparing MF-electrodes from different metal-SPEs was described. An optimal electrolyzer construction for the mercury deposition, electrolyte composition, electrolysis potential, and an activation of electrode surfaces were proposed. Determination of the zinc content in food supplement tablets was used for the MF-SPEs practical testing.
Electrochemical Techniques in Monitoring of Nervous System Drugs
Choińska-Mlynarczyk, Marta ; Hrdlička, Vojtěch ; Skopalová, J. ; Šelešovská, R. ; Kolivoška, Viliam ; Navrátil, Tomáš
Drugs of the nervous system (ATC group N) belong generally to the most commonly (mis)used substances worldwide. Their determination and monitoring of these drugs and their metabolites in various body fluids or environmental matrices represent a challenge for analytical chemists. Our research is focused on the application of electrochemical methods in the monitoring of the most frequently prescribed and the newly introduced nervous system drugs of precisely specified structures and/or of defined properties. For toxicological and pharmacokinetic reasons, emphasis has been placed on investigating the reaction mechanisms of their metabolite formation. New or alternative to commonly used electroanalytical methods applicable for monitoring and characterization of target compounds in their pure state, in body fluids, wastewaters, and other environmental matrices, has been developed. To improve the chemometric parameters and sensing characteristics, attention was paid to the construction of new electrochemical sensors, detectors (e.g. screen-printed, 3D printed), or cells, based on (modified/unmodified) traditional or nontraditional materials, preferably usable at the point-of-care.
Voltammetric Determination of Psilocin and Psilocybin at Carbon-fiber PLA Electrode
Choińska-Mlynarczyk, Marta ; Navrátil, Tomáš
Psilocin and psilocybin are two neuroactive drugs. They can be used in experimental treatment in psychiatry, moreover, also as illicit drugs to achieve hallucinations and relaxation. Easy access to these two alkaloids indicates that their monitoring in the environment and the body fluids is necessary. Electrochemistry offers fast, simple, and easy methods of their determination using laboratory-manufactured electrodes from 3D printed carbon-fiber polylactic materials. This technique of electrode fabrication can be characterized by many benefits, e.g., desired shape or diameter of the electrode, well-developed voltammetric signals, and low background currents.
Determination of heavy metal poisoning antidote 2,3-dimercapto-1-propanesulfonic acid using silver solid amalgam electrode
Choińska-Mlynarczyk, Marta ; Hrdlička, Vojtěch ; Redondo, B. R. ; Barek, J. ; Navrátil, Tomáš
2,3-Dimercapto-1-propane-sulfonic acid (DMPS) was investigated using direct current voltammetry (DCV), differential pulse cathodic stripping voltammetry (DPCSV), differential pulse anodic stripping voltammetry (DPASV), and elimination voltammetry with linear scan (EVLS) at a polished (p-AgSAE)and at a meniscus modified silver solid amalgam electrode (m-AgSAE). EVLS confirmed two consecutive reductions with coupled proton/electron transfer. Voltammetric titrations of DMPS with Pb2+ proved complex formation, with limits of quantification (LOQs) and detection (LODs) 0.3 and 0.1 mu mol L-1 at m-AgSAE and 0.8 and 0.3 mu mol L-1 at p-AgSAE, respectively. Determination of DMPS in commercial drug Dimaval and human urine samples confirmed practical applicability of the developed method.
Voltammetric Determination of Heavy Metals in Honeybee Venom using Hanging Mercury Drop Electrode and Carbon Conductive Filaments for 3D Printer
Navrátil, Tomáš ; Choińska-Mlynarczyk, Marta ; Šestáková, Ivana ; Hrdlička, Vojtěch
Heavy metals belong to typical contaminants of our environment. It is known that they are\nmetabolized and incorporated into bee products as honey as well as honeybee venom (apitoxin).\nIt is supposed that their composition can reflect contamination of the “bee environment” and\ncan give us information about the environment in the neighborhood of human dwellings.\nThis study aimed to develop a simple method for the determination of heavy metals in honeybee\nvenom. Due to the complicated matrix, wet microwave mineralization with sulfuric acid, nitric\nacid, under increased temperature and pressure, and repeated boiling with concentrated nitric\nacid had to be applied. Voltammetry proved to be very suitable for the determination of heavy\nmetals.\nTwo types of working electrodes have been used: pen-type hanging mercury drop electrode and\ncarbon conductive filaments for 3D printers. Results achieved using both of them and their\nadvantages and limitations have been compared.
Metallothioneins as Biomarker of Environmental Pollution
Šestáková, Ivana ; Křivská, D. ; Navrátil, Tomáš
Small wild mammals living at contaminated soil are exploited for monitoring of their metal and\nmetallothionein (MT) levels, which can be influenced by presence of parasites. This has been\ntested in laboratory experiment with white rats (Rattus norvegicus) infected with tapeworm\nHimenolepis diminuta and given diet enriched with lead or zinc. The influence of parasite was\nconfirmed with analysis of samples, where metal concentrations in infected groups were\nlowered in comparison with the uninfected rats. Within infected groups, tapeworms MT levels\nwere 6 or 3 times higher than MT in tapeworms of the control group. Obtained results support\npossibility of using MT concentration in Himenolepis diminuta for biomonitoring.
Determination of Selected Drugs using 3D Printed Electrodes
Choińska-Mlynarczyk, Marta ; Hrdlička, Vojtěch ; Navrátil, Tomáš
The main aim of this research was to develop a new method for voltammetric determination of\npopular antidepressants, analgesics, and illicit drugs using a laboratory-made 3D printed\nelectrode and to compare the achieved results with those registered using a commercially\navailable glassy carbon electrode. These experiments represent the first step in the development\nof a method applicable in clinical and forensic praxis for the rapid and inexpensive\ndetermination of commonly misused groups of biologically active compounds.

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