Národní úložiště šedé literatury Nalezeno 14 záznamů.  1 - 10další  přejít na záznam: Hledání trvalo 0.01 vteřin. 
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.
Voltametrické stanovení těžkých kovů ve včelím jedu za použití rtuťové kapkové elektrody a uhlíkového vodivého filamentu pro 3D tisk
Navrátil, Tomáš ; Choińska-Mlynarczyk, Marta ; Šestáková, Ivana ; Hrdlička, Vojtěch
Včelí jed představuje sekret z jedového ústrojí včelích dělnic nebo včelí matky (nikoliv trubců).\nSmrtelná dávka pro člověka je asi 400-700 žihadel, LD50 myší i.v.=0,6 mg/kg. Po vysušení\nvzniká světle žlutý, velmi jemný prášek. Je rozpustný ve vodě za vzniku opaleskujícího roztoku.\nTypické složení (procenta představují podíl látky v sušině):\n -50-55 % silně bazický polypeptid melitin (poškozuje červené i bílé krvinky), 2-3 %\nappamin (vliv na nervovou soustavu), MCD (mast cell degranulating) peptid (narušuje\nčinnost buněčných membrán,\n Enzymy: 13-14 % fosfolypáza A a B, 2-3 % hyaluronidáza,\n Biogenní aminy: histamin, dopamin, noradrenalin.\nKromě výše uvedených látek jsou v jedu, podobně jako ve včelím medu, obsaženy látky, se\nkterými přichází tento blanokřídlý hmyz do styku během svého života. Jedná se tedy i o těžké\nkovy, kterými je kontaminováno naše životní prostředí. Analýza včelího jedu včel\nmedonosných žijících ve zvolené oblasti může tedy poskytnout informaci o plošném znečištění\npoměrně velké oblasti.
Metalothioneiny jako biomarkery znečištění životního prostředí
Šestáková, Ivana ; Křivská, D. ; Navrátil, Tomáš
Sledování obsahu metalothioneinů jako biomarkeru znečištění vodního prostředí je\npředmětem řady studií i mezinárodního programu (Mediterranean Action Plan of The United\nNations Environment Program, 1999). Pro sledování vlivu kontaminace půdy jsou vhodnou\nmožností volně žijící drobní savci, kde hladiny metalothioneinů závisí na obsazích kovů\nv půdě, a i na dietních zvyklostech (omnivoři, herbivoři, karnivoři). V posledním desetiletí\nnabývají na významu studie vlivu parazitů, kde je popisován jak pozitivní, tak negativní vliv\nparazitů na obsahy kovů ve tkáních hostitele. U některých parazitů ryb byl zjištěn řádový nárůst\nobsahu kovů ve tkáních parazitu, který vedl k uvažování možnosti užití právě parazitů jako\nindikátoru znečištění.
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.

Národní úložiště šedé literatury : Nalezeno 14 záznamů.   1 - 10další  přejít na záznam: