Electrochemical (EC) detection techniques in flow-based analytical systems such as flow injection analysis (FIA), capillary electrophoresis (CE), and liquid chromatography (LC) have attracted continuous interest over the last three decades, leading to significant advances in EC detection of a wide range of analytes in the liquid phase. In this context, the unique advantages of pulsed amperometric detection (PAD) in terms of high sensitivity and selectivity, and electrode cleaning through the application of pulsed potential for noble metal electrodes (e.g. Au, Pt), have established PAD as an important detection technique for a variety of electrochemically active compounds. PAD is especially valuable for analytes not detectable by ultraviolet (UV) photometric detection, such as organic aliphatic compounds and carbohydrates, especially when used with miniaturised capillary and chip-based separation methods. These applications have been accomplished through advances in PAD potential waveform design, as well as through the incorporation of nanomaterials (NMs) employed as microelectrodes in PAD. PAD allows on-line pulsed potential cleaning and coupling with capillary or standard separation techniques. The NMs are largely employed in microelectrodes to speed up mass and electron transfer between electrode surfaces and to perform as reactants in EC analysis. These advances in PAD have improved the sensitive and selective EC detection of analytes, especially in biological samples with complex sample matrices, and detection of electro-inactive compounds such as aliphatic organic compounds (i.e., formic acid, acetic acid, maleic acids, and β-cyclodextrin complexes). This review addresses the fundamentals of PAD, the role of pulsed sequences in AD, the utilisation of different EC detectors for PAD, technological advancements in PAD waveforms, utilisation of microelectrodes in PAD techniques, advances in the use of NMs in PAD, the applications of PAD, and prospects for EC detection, with emphasis on PAD in flow-based systems.

• Klíčová slova
• Electrochemical detector, Flow-based analytical systems, Pulsed amperometric detection,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Hydrogen peroxide (H2O2) is known to be generated in Photosystem II (PSII) via enzymatic and non-enzymatic pathways. Detection of H2O2 by different spectroscopic techniques has been explored, however its sensitive detection has always been a challenge in photosynthetic research. During the recent past, fluorescence probes such as Amplex Red (AR) has been used but is known to either lack specificity or limitation with respect to the minimum detection limit of H2O2. We have employed an electrochemical biosensor for real time monitoring of H2O2 generation at the level of sub-cellular organelles. The electrochemical biosensor comprises of counter electrode and working electrodes. The counter electrode is a platinum plate, while the working electrode is a mediator based catalytic amperometric biosensor device developed by the coating of a carbon electrode with osmium-horseradish peroxidase which acts as H2O2 detection sensor. In the current study, generation and kinetic behavior of H2O2 in PSII membranes have been studied under light illumination. Electrochemical detection of H2O2 using the catalytic amperometric biosensor device is claimed to serve as a promising technique for detection of H2O2 in photosynthetic cells and subcellular structures including PSII or thylakoid membranes. It can also provide a precise information on qualitative determination of H2O2 and thus can be widely used in photosynthetic research.

• Klíčová slova
• EPR-spin trapping, amperometric biosensor, hydrogen peroxide, photosystem II, reactive oxygen species, superoxide anion radical,
• Publikační typ
• časopisecké články MeSH

A new method for the simultaneous determination of two tumour biomarkers, homovanillic (HVA) and vanillylmandelic acid (VMA), using flow injection analysis (FIA) with amperometric detection (AD) at a commercially available boron doped diamond electrode (BDDE) was developed. It was found that this method is suitable for the determination of HVA (in the presence of VMA) and VMA (in the presence of HVA) in optimum medium of Britton-Robinson buffer (0.04 mol L-1, pH 3.0). Calibration dependences consist of two linear parts for both biomarkers, the first one being in the concentration range from 1 to 10 μmol L-1 and the second one from 10 to 100 μmol L-1 (with obtained LODs 0.44 μmol L-1 for HVA and 0.34 μmol L-1 for VMA, respectively). To minimize any negative effects related to the passivation of the working electrode, suitable cleaning pulses (+2.4 V for 30 s) were imposed on the working electrode after each measurement. An attempt to use FIA with multiple pulse amperometric detection to determine both analytes in one run was not successful. Changing potentials in short intervals in multiple pulse detection probably results in mutual interaction of analytes and/or products of their electrochemical oxidation, thus preventing the application of this approach.

• Klíčová slova
• Boron doped diamond electrode, Flow injection analysis, Homovanillic acid, Tumour biomarkers, Vanillylmandelic acid,
• MeSH
• bor chemie   MeSH
• diamant chemie   MeSH
• elektrochemické techniky přístrojové vybavení   metody   MeSH
• elektrody MeSH
• kyselina homovanilová analýza   chemie   MeSH
• kyselina vanilmandlová analýza   chemie   MeSH
• limita detekce MeSH
• nádorové biomarkery analýza   chemie   MeSH
• oxidace-redukce MeSH
• průtoková injekční analýza metody   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bor MeSH
• diamant MeSH
• kyselina homovanilová MeSH
• kyselina vanilmandlová MeSH
• nádorové biomarkery 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

A porous layer of copper was formed on the surface of screen-printed carbon electrodes via the colloidal crystal templating technique. An aqueous suspension of monodisperse polystyrene spheres of 500 nm particle diameter was drop-casted on the carbon tracks printed on the substrate made of alumina ceramic. After evaporation, the electrode was carefully dipped in copper plating solution for a certain time to achieve a sufficient penetration of solution within the polystyrene spheres. The metal was then electrodeposited galvanostatically over the self-assembled colloidal crystal. Finally, the polystyrene template was dissolved in toluene to expose the porous structure of copper deposit. The morphology of porous structures was investigated using scanning electron microscopy. Electroanalytical properties of porous copper film electrodes were evaluated in amperometric detection of selected saccharides, namely glucose, fructose, sucrose, and galactose. Using hydrodynamic amperometry in stirred alkaline solution, a current response at +0.6 V vs. Ag/AgCl was recorded after addition of the selected saccharide. These saccharides could be quantified in two linear ranges (0.2-1.0 μmol L-1 and 4.0-100 μmol L-1) with detection limits of 0.1 μmol L-1 glucose, 0.03 μmol L-1 fructose, and 0.05 μmol L-1 sucrose or galactose. In addition, analytical performance of porous copper electrodes was ascertained and compared to that of copper film screen-printed carbon electrodes, prepared ex-situ by the galvanostatic deposition of metal in the plating solution. After calculating the current densities with respect to the geometric area of working electrodes, the porous electrodes exhibited much higher sensitivity to changes in concentration of analytes, presumably due to the larger surface of the porous copper deposit. In the future, they could be incorporated in detectors of flow injection systems due to their long-term mechanical stability.

• Klíčová slova
• amperometric detection, colloidal crystal templating, non-enzymatic sensors, porous copper electrodes, sensing of saccharides,
• MeSH
• elektrody MeSH
• fruktosa MeSH
• galaktosa MeSH
• glukosa MeSH
• měď * chemie   MeSH
• polystyreny MeSH
• sacharosa MeSH
• uhlík * chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fruktosa MeSH
• galaktosa MeSH
• glukosa MeSH
• měď * MeSH
• polystyreny MeSH
• sacharosa MeSH
• uhlík * MeSH

BACKGROUND: Electrochemistry offers a range of powerful techniques for solving analytical problems, each with its own advantages and limitations that can significantly affect the information obtained. These variations lead to diverse requirements for newly developed methods. Applying multiple electrochemical techniques simultaneously can optimize information extraction from a sample, aiding in the selection of the best analytical approach. RESULTS: In this study, we present the first investigation of the oxidation of the coccidiostat nicarbazin, along with a comparative evaluation of two established electrochemical methods with complementary strengths: differential pulse voltammetry (DPV) and capillary electrophoresis coupled with amperometric detection (CE-AD). We thoroughly examine the oxidative determination of nicarbazin in poultry feed samples using acetonitrile based media. DPV allows for rapid and efficient analysis, while CE-AD excels in handling complex samples with electrochemically active species due to its high separation efficiency. Both methods exhibit limits of detection (LODs) in the low micromolar range. To provide a comprehensive understanding of the nicarbazin oxidation process, the final reaction products were analyzed by mass spectrometry, identifying 4-nitroaniline and (4-nitrophenyl)formamide as key product compounds. SIGNIFICANCE AND NOVELTY: This pioneering research on the anodic detection of nicarbazin includes a detailed analysis of the components in the studied equimolar mixture. The developed protocols, combined with straightforward sample preparation, enable the successful determination of nicarbazin levels below those allowed by EU regulations.

• Klíčová slova
• Capillary electrophoresis, Complementary study, Differential pulse voltammetry, Electrochemical detection, Electrochemistry, Mass spectrometry, Quality control,
• Publikační typ
• časopisecké články MeSH

The mechanism of amperometric detection with a copper electrode has been studied with four amino-acids in four different carrier liquids containing aqueous buffer and methanol. It is concluded that the response is produced by complexation of the test substances with cupric ions in the outer, porous layer of the passivating film, with formation of CuL(+) species. The increase in detector current is primarily determined by the complexation kinetics and to a lesser degree by the stability of the complex formed. The complexation rate strongly decreases with increasing amounts of organic solvent in the carrier liquid. The optimal detection conditions are discussed on the basis of the detection mechanism. Results are given for the detection of various structural types of amines and amino-alcohols.

• Publikační typ
• časopisecké články MeSH

A capillary electrophoretic method for the separation of four mercury species with amperometric detection was developed. Inorganic Hg2+, methyl-, ethyl-, and phenyl-mercury were complexed with L-cysteine and separated in a counterelectroosmotic mode in an electrolyte solution comprised of 20 mM sodium tetraborate at pH 9.5. Amperometric detection of separated species was achieved at passivated copper electrode under electrocatalytic oxidation conditions. The four mercury species were separated in less than 8 min with LODs ranging from 170 to 450 microg/L. Cation exchange preconcentration was used to decrease the LODs down to 1.7 microg/L.

• MeSH
• časové faktory MeSH
• elektrochemie MeSH
• elektrody MeSH
• elektroforéza kapilární přístrojové vybavení   metody   MeSH
• iontová výměna MeSH
• kationty chemie   MeSH
• měď chemie   MeSH
• mikrofluidní analytické techniky přístrojové vybavení   metody   MeSH
• rtuť analýza   MeSH
• senzitivita a specificita MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kationty MeSH
• měď MeSH
• rtuť MeSH

Correction for 'Evaluation of a nitrogen-incorporated tetrahedral amorphous carbon thin film for the detection of tryptophan and tyrosine using flow injection analysis with amperometric detection' by Romana Jarošová, et al., Analyst, 2016, DOI: .

• Publikační typ
• časopisecké články MeSH
• tisková chyba MeSH

The chromatographic behaviour of eighteen s-triazine derivatives has been studied in a reversed-phase system with a Separon SIC 18 stationary phase and a mobile phase of aqueous sodium dihydrogenphosphate and methanol. The dependences of the capacity factors on the methanol content, the pH and the ionic strength have been obtained. Ultraviolet photometric detection can generally be used whereas amperometric detection with a carbon-fibre array electrode is useful for selective detection of s-triazine hydroxy derivatives, but with a sensitivity poorer than that of photometric detection. The method has been applied to a study of the photolysis of s-triazines and the effect of the substituents and the pH on the photolysis rate.

• MeSH
• biodegradace MeSH
• elektrochemie MeSH
• fotolýza MeSH
• fotometrie MeSH
• herbicidy analýza   izolace a purifikace   MeSH
• indikátory a reagencie MeSH
• methanol MeSH
• spektrofotometrie ultrafialová MeSH
• triaziny * MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• herbicidy MeSH
• indikátory a reagencie MeSH
• methanol MeSH
• triaziny * MeSH