This article reviews the development in ion amperometry at the interface between two immiscible electrolyte solutions (ITIES) in view of realizing the amperometric ion-selective electrode (ISE). The concept of polarizability of ITIES in a multi-ion system is outlined. Principle aspects of ion amperometry at ITIES are discussed including the use of amperometry as a tool for the clarification of the ion sensing mechanism, and for determining the concentrations of ions in the solution. The reference is made to recent amperometric measurements at the supported liquid membrane (SLM) and polymer composite liquid membranes (PCLM), which, together with the micro-hole supported ITIES, appear to be particularly suitable for realization of the amperometric ISE.

• Publikační typ
• časopisecké články MeSH

Optimum conditions have been found for the chelometric determination of indium by biamperometric titration with EDTA. Two stationary platinum electrodes (Pt-Pt) or two graphite electrodes (C-C) may be used to indicate the end-point of the titration. At pH 1-1.5 the determination is highly selective. The applied potential only influences the absolute value of the current ; the accuracy of the determinations remains constant over a wide interval of applied potential. At a potential of 1.0-1.7 V the change of current during a titration with 0.05 M EDTA solution is of the order of 10 microA. Analytical applications of the method are discussed.

• Publikační typ
• časopisecké články MeSH

Optimum conditions have been found for a highly selective determination of bismuth via EDTA titration with biamperometric indication of the end-point. The influence of the applied potential, pH and stirring on the accuracy and selectivity of the determination has been studied. In a medium of 0.4M nitric acid only high concentrations of iron(III) and copper(II) interfere with the determination of bismuth. Zirconium, thallium(III) and indium interfere even in small concentrations. The average error of the determination of 5-100 mg of bismuth (when titrated with 0.05M EDTA solution) is +/-0-1 % rel. and for the determination of 0.5-10 mg it is +/-0.3% rel. (0.005M EDTA). The method has been verified by the analysis of a Wood's metal of known composition.

• Publikační typ
• časopisecké články MeSH

This work describes the method for total antioxidant capacity (TAC) and/or total content of phenolics (TCP) analysis in wines using microdialysis online-coupled with amperometric detection using a carbon microfiber working electrode. The system was tested on 10 selected wine samples, and the results were compared with total reactive antioxidant potential (TRAP), oxygen radical absorbance capacity (ORAC), and chemiluminescent determination of total antioxidant capacity (CL-TAC) methods using Trolox and catechin as standards. Microdialysis online-coupled with amperometric detection gives similar results to the widely used cyclic voltammetry methodology and closely correlates with ORAC and TRAP. The problem of electrode fouling is overcome by the introduction of an electrochemical cleaning step (1-2 min at the potential of 0 V vs Ag/AgCl). Such a procedure is sufficient to fully regenerate the electrode response for both red and white wine samples as well as catechin/Trolox standards. The appropriate size of microdialysis probes enables easy automation of the electrochemical TAC/TCP measurement using 96-well microtitration plates.

• MeSH
• antioxidancia analýza   MeSH
• elektrochemické techniky přístrojové vybavení   metody   MeSH
• mikrodialýza MeSH
• mikroelektrody MeSH
• polyfenoly analýza   MeSH
• uhlík MeSH
• víno analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• antioxidancia MeSH
• polyfenoly MeSH
• uhlík MeSH

We report the first amperometric method for the simultaneous determination of tert-butylhydroquinone (tBHQ), propyl gallate (PG), and butylated hydroxyanisole (BHA) using flow injection analysis coupled to multiple-pulse amperometry. A sequence of potential pulses was selected in order to detect tBHQ, PG, and BHA separately in a single injection step at a glassy carbon electrode without the need of a preliminary separation. A mixture of methanol and 0.040M Britton-Robinson buffer was used both as a carrier solution and for dilution of analyzed solutions before injection. The method is precise (RSD < 5%, n = 10), fast (a frequency of 140 injections h-1), provides sufficiently low quantification limits (2.51, 1.45, and 0.85μmolL-1 for tBHQ, PG, and BHA, respectively) and can be easily applied without high demands on instrumentation. As a practical application, the determination of these antioxidants contained in commercial chewing gum samples was carried out by applying a simple extraction procedure.

• Klíčová slova
• Antioxidants, Flow injection analysis, Glassy carbon electrode, Multiple-pulse amperometry,
• MeSH
• butylhydroxyanisol analýza   MeSH
• časové faktory MeSH
• elektrochemie přístrojové vybavení   metody   MeSH
• elektrody MeSH
• hydrochinony analýza   MeSH
• propylgalan analýza   MeSH
• průtoková injekční analýza * MeSH
• žvýkačka analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 2-tert-butylhydroquinone MeSH Prohlížeč
• butylhydroxyanisol MeSH
• hydrochinony MeSH
• propylgalan MeSH
• žvýkačka MeSH

Biosensors are analytical devices being approachable for multiple analytes assay. Here, biosensors with intercepted acetylcholinesterase (AChE) or butyrylcholinesterase (BChE) are presented as tool for assay of anticholinergic compounds such as pesticides, nerve agents and some natural toxins. Principle of assay is based on evaluation of cholinesterase activity and its pertinent decrease in presence of analyte. Nerve agents, pesticides, anticholinergic drugs useable for treatment of Alzheimer's disease as well as myasthenia gravis and aflatoxins are enlisted as compounds simply analyzable by cholinesterase biosensors.

• Klíčová slova
• acetylcholinesterase, amperometry, biosensor, butyrylcholinesterase, carbamates, organophophates, organophosphonates,
• Publikační typ
• časopisecké články MeSH

Chloride ion sensing is important in many fields such as clinical diagnosis, environmental monitoring and industrial applications. We have measured chloride ions at a carbon paste electrode (CPE) and at a CPE modified with solid AgNO₃, a solution of AgNO₃ and/or solid silver particles. Detection limits (3 S/N) for chloride ions were 100 μM, 100 μM and 10 μM for solid AgNO₃, solution of AgNO₃ and/or solid silver particles, respectively. The CPE modified with silver particles is the most sensitive to the presence chloride ions. After that we approached to the miniaturization of the whole electrochemical instrument. Measurements were carried out on miniaturized instrument consisting of a potentiostat with dimensions 35 × 166 × 125 mm, screen printed electrodes, a peristaltic pump and a PC with control software. Under the most suitable experimental conditions (Britton-Robinson buffer, pH 1.8 and working electrode potential 550 mV) we estimated the limit of detection (3 S/N) as 500 nM.

• Klíčová slova
• Amperometry, Carbon Paste Electrode, Chloride Ions, Screen Printed Electrode, Silver, Voltammetry,
• Publikační typ
• časopisecké články MeSH

RESEARCH BACKGROUND: The objective of this paper is to introduce an instrumentally simple analytical tool for determination of cocoa solid content in chocolates. This electroanalytical method is based on amperometric oxidation of all present antioxidants in chocolates at boron-doped diamond electrode (BDDE) that is integrated in a flow injection analysis (FIA) wall-jet electrode system. EXPERIMENTAL APPROACH: As part of optimisation, thirteen commonly occurring antioxidants were investigated using cyclic voltammetry at the BDDE in 0.1 mol/L phosphate buffer with different methanol (MeOH) content. Working parameters, such as MeOH volume fraction, flow rate and detection potential, were optimised. Principally, the height of the oxidation peak (current response) representing the oxidation of the sum of antioxidants (total antioxidant content; TAC) was expressed as Trolox equivalents. RESULTS AND CONCLUSIONS: For analytical purpose, a linear range from 5 to 100 mg/L described by regression equation and characterised by high correlation coefficient R2=0.9994 was achieved. Obtained high positive correlation between the determined values of Trolox equivalent antioxidant capacity (TEAC) and cocoa mass fractions characterised by correlation coefficient of 0.9187 for eight randomly selected samples (one white, two milk, and five dark chocolates) confirmed that cocoa solids represent the main source of antioxidants (reducing agents). NOVELTY AND SCIENTIFIC CONTRIBUTION: The research demonstrates that TEAC values could be considered as an additional marker of cocoa content in the chocolate analysis to the commonly used theobromine (authenticity of food products). The developed FIA could therefore serve as simple analytical tool in the food quality control.

• Klíčová slova
• Trolox equivalent antioxidant capacity, amperometry, boron-doped diamond electrode, cocoa mass fraction in chocolate, flow injection analysis,
• Publikační typ
• časopisecké články MeSH

The review describes fentanyl and its analogs as new synthetic opioids and the possibilities of their identification and determination using electrochemical methods (e.g., voltammetry, potentiometry, electrochemiluminescence) and electrochemical methods combined with various separation methods. The review also covers the analysis of new synthetic opioids, their parent compounds, and corresponding metabolites in body fluids, such as urine, blood, serum, and plasma, necessary for a fast and accurate diagnosis of intoxication. Identifying and quantifying these addictive and illicit substances and their metabolites is necessary for clinical, toxicological, and forensic purposes. As a reaction to the growing number of new synthetic opioid intoxications and increasing fatalities observed over the past ten years, we provide thorough background for developing new biosensors, screen-printed electrodes, or other point-of-care devices.

• Klíčová slova
• amperometry, fentanyl, fentanyl analogs, metabolite, oxidation, screen-printed electrode, voltammetry,
• MeSH
• fentanyl * MeSH
• opioidní analgetika * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• fentanyl * MeSH
• opioidní analgetika * MeSH

Routine determination of trace metals in complex media is still a difficult task for many analytical instruments. The aim of this work was to compare three electro-chemical instruments [a standard potentiostat (Autolab), a commercially available miniaturized potentiostat (PalmSens) and a homemade micropotentiostat] for easy-to-use and sensitive determination of cadmium(II) and lead(II) ions. The lowest detection limits (hundreds of pM) for both metals was achieved by using of the standard potentiostat, followed by the miniaturized potentiostat (tens of nM) and the homemade instrument (hundreds of nM). Nevertheless, all potentiostats were sensitive enough to evaluate contamination of the environment, because the environmental limits for both metals are higher than detection limits of the instruments. Further, we tested all used potentiostats and working electrodes on analysis of environmental samples (rainwater, flour and plant extract) with artificially added cadmium(II) and lead(II). Based on the similar results obtained for all potentiostats we choose a homemade instrument with a carbon tip working electrode for our subsequent environmental experiments, in which we analyzed maize and sunflower seedlings and rainwater obtained from various sites in the Czech Republic.

• Klíčová slova
• amperometry, cadmium, heavy metals, lead, maize, miniaturization, plant, screen printed electrode, sunflower, voltammetry, water,
• MeSH
• automatizace MeSH
• biosenzitivní techniky přístrojové vybavení   metody   MeSH
• elektrochemie přístrojové vybavení   metody   MeSH
• ionty analýza   MeSH
• kadmium analýza   MeSH
• kukuřice setá chemie   MeSH
• mikroelektrody MeSH
• monitorování životního prostředí přístrojové vybavení   metody   MeSH
• olovo analýza   MeSH
• rostliny chemie   MeSH
• stopové prvky analýza   MeSH
• uhlík chemie   farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ionty MeSH
• kadmium MeSH
• olovo MeSH
• stopové prvky MeSH
• uhlík MeSH