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Spectroelectrochemical Devices for Monitoring of Intermediates and Products on Carbonbased Composite Electrodes
Vaněčková, Eva ; Šikula, M. ; Hrdlička, Vojtěch ; Sebechlebská, Táňa ; Kolivoška, Viliam
Spectroelectrochemistry (SEC), as an interdisciplinary field, provides us with more comprehensive information about electroactive molecules involved in charge transfer reactions. Commercially\navailable SEC cells most often have an incorporated platinum working electrode, which can limit the range of the usable potential window and, in addition, can complicate the analysis due to the\nabsorption phenomenon. In this work, we designed and manufactured two types of custom-made SEC cells employing optically transparent carbon-based working electrodes for UV-Vis monitoring of reactants and electrogenerated intermediates and products. The first SEC cell is entirely manufactured by 3D printing using fused deposition modeling (FDM) by combining optically transparent (PET) and electrically conductive (PLA-CB) filaments. The second SEC cell employs pencil graphite (PG) rods as the working electrode (PGE) and its body is manually assembled from quartz slides. The functionality of the FDM 3D printed SEC cell and manually assembled quartz SEC cell were verified by cyclic voltammetry with in situ UV-Vis spectroscopic absorption monitoring of ruthenium(III) acetylacetonate (Ru(ac)3) redox-active probe dissolved in an aqueous or non-aqueous deaerated solvent, respectively. Both presented cells enable complete redox reversible conversion and strictly oxygen-free conditions.
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Optimization of Parameters Used in the Application of Elimination Voltammetry with Linear Scan
Navrátil, Tomáš ; Trnková, L. ; Hrdlička, Vojtěch ; Li, X.
Elimination Voltammetry with Linear Scan (EVLS) is a well-established mathematical method that aids in understanding an analyzed electrochemical system. In almost 30 years since its derivation, it has become a “black-box” technique that is applied automatically (in most cases due to its incorporation into a voltammetric software) without thinking about its fundamentals. However, the choice of optimum parameters under which DC voltammetric data (from which elimination curves are calculated) is crucial. This contribution deals with revealing the optimum ratio of applied scan rates and their absolute values (i.e., times of recording) in dependence on the character of the investigated system (diffusion-controlled process, adsorption-controlled process, etc.).
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A New Hollow Fiber-Based Liquid-Phase Microextraction Method for the Determination of Antihypertensive Drug Lercanidipine in Biological Samples
Labzova, O. ; Hrdlička, Vojtěch ; Navrátil, Tomáš ; Šelešovská, R.
A new hollow fiber-based liquid-phase microextraction (HF-LPME) method for the determination of antihypertensive drug lercandipine (LCN) in biological samples was developed. HF-LPME was\ncombined with optimized square wave voltammetry (SWV) on a cathodically pre-treated screenprinted boron-doped diamond electrode (SP-BDDE). Optimum HF-LPME conditions were:\nsupported liquid membrane (SLM) dodecane, 0.02 mol L-1 Britton-Robinson buffer (BRB, pH = 3) acceptor phase, BRB (pH = 7) donor phase, and time of extraction 30 min. Limits of quantification (LOQ) and detection (LOD) were 3.3 and 1.1 nmol L-1, respectively. The applicability of the developed method was verified on human urine, blood serum, and blood plasma with 20 and 100 nmol L-1 LCN addition.
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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
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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.
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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.
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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.
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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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The use of Boron Doped Diamond Electrode for Determination of 5-hydroxyindoleacetic Acid
Hrdlička, Vojtěch ; Navrátil, Tomáš
A new method for voltammetric determination of clinical biomarker 5-hydroxyindoleacetic\nacid (HIAA) at the boron-doped diamond electrode (BDDE) was developed. Anodically and\ncathodically pretreated BDDEs were tested in the pH ranges from 1 to 12, pre-treatment at\n+2.0V/60 s, and pH 3 was found to be the optimum.\nThe optimum square wave voltammetry (SWV) parameters were: f = 12 Hz, amplitude 60\nmV, and potential step 4 mV. SWV concentration dependency was constructed in the range\nfrom 0.1 to 100 μmol L−1, limits of determination and detection were 0.3 and 0.1 μmol L−1,\nrespectively. HIAA oxidation electrode process at BDDE was diffusion-controlled, as\nuncovered by cyclic voltammetry. Interestingly, HIAA peak potential was constant in various\nranges of pH, indicating a non-Nernstian behavior at the BDDE, in contrast to a previously\npublished electrooxidation mechanism consisting of a coupled H+/e− transfer.
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3D printed materials for the electrochemical determination of biologically active compounds
Choińska, Marta Katarzyna ; Navrátil, Tomáš ; Hrdlička, Vojtěch
3D printing materials are relatively novel materials in electrochemistry,\nused for manufacturing of electrochemical cells, electrodes\netc. They have been widely used mainly for tailored, fast, inexpensive,\nand easy preparation of various equipment for analyses of\nbiologically active compounds. Various medicinal products and illicit\ndrugs belong to this broad group of analytes which need to be\nmonitored because of the possibility of (un)intentional overdose or\nrecreational consumption, which can cause serious side effects or\neven death. Due to this risk, we decided to focus our research on the\ndevelopment of new, sensitive, selective, and easily customizable 3D\nprinted sensors for the determination of some commonly used\nantidepressants, analgesics, and illicit drugs.
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