8/2013-14 Sensing in Electroanalysis

Permanentní URI k tomuto záznamuhttps://hdl.handle.net/10195/56677

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Applicability of electrodes modified with composite layers of conducting polymers in electro- and bioelectroanalysis
(Univerzita Pardubice, 2014) Socha, Ewelina; Krzyczmonik, Paweł; Skrzypek, Sławomira
Obtaining modified electrodes is a response of electrochemistry to continuous development in areas such as technology, electronics, medicine, biology and many others. Modifying layers allow scientists to build electrodes with required properties such as for example: selectivity, stability, precision, durability, range of potentials etc. The aim of the studies was to modify the surface of gold and platinum with the layer of poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) doped with various organic acids and their salts. Additives such as p–toluenesulfonic acid (PTSA), dodecylbenzene-sulfonic acid (DBSA), poly(4-styrenesulfonic acid) (PSSH) and poly(4-lithium styrenesulfonic acid) (PSSLi) were used. The main application of these electrodes was the determination of ascorbic acid, uric acid and catecholamines (dopamine, epinephrine). Another modification covered the preparation of PEDOT/polyacrylic acid (PAA)/PSSLi layer with available free carboxyl groups and afterwards the immobilization of glucose oxidase via covalent bond through N-(3- dimethylaminopropyl)-N′-ethylcarbodiimide (WSC). The purpose of the research on selected modifications was to find electrodes that could be applied in electroanalysis as sensors to determine chosen biologically active compounds. Low capacity current, wide range of potentials, the ability to work in the broadest pH range, especially physiological pH was required. The third modification gave rise to the honeycomb structure with the increased area of electrode surface and the use of PEDOT/PAA/PSSLi allows us to immobilize enzyme.
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Boron doped diamond electrodes in voltammetry: new designs and applications (an overview)
(Univerzita Pardubice, 2014) Zavázalová, Jaroslava; Barek, Jiří; Pecková, Karolina
In this overview, the recent progress in the development and applications of bare boron doped diamond electrodes in voltammetry of organic compounds is summarized. Attention is paid to important issues reflected in last five years in electroanalytical studies, e.g. fouling and pretreatment of BDD surface, influence of boron concentration on performance of BDD-based sensors, and application of adsorptive stripping voltammetry.
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Carbon paste electrodes bulk-modified with carbon nanotubes and chemically oxidized carbon nanotubes for the determination of hydrogen peroxide
(Univerzita Pardubice, 2014) Zbiljić, Jasmina; Vajdle, Olga; Guzsvány, Valéria; Kónya, Zoltán; Kukovecz, Ákos; Dalmacija, Božo; Kalcher, Kurt
Carbon paste electrodes (graphite/paraffin oil) bulk-modified with multiwalled carbon nanotubes (MWCNT) and chemically oxidized MWCNT (O-MWCNT) were used as sensors for the hydrodynamic chronoamperometric determination of hydrogen peroxide (H2O2). Experimental parameters, such as the type and pH of the supporting electrolyte or the working potential(s) applied were investigated in the batch arrangement.
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Common methods to detect mycotoxins: a review with particular emphasis on electrochemical detection
(Univerzita Pardubice, 2014) Bueno, Diana; Muñoz, Roberto; Marty, Jean Louis
Mycotoxins are metabolites produced naturally, due to their presence in foodstuffs and their potential risk for human health, the food industries require analytical methods to secure the quality and stability of raw materials, processes and products. These methods must offer real time data that allow to control and to monitor each process to safeguard the innocuity of the nutritional products. The traditional analytical methods have to deal determinations with limited sensitivity levels and little specificity, they are expensive. Although the chromatographic methods show highly reproducible results and good limits of detection. Other alternative is the use of biosensors. In this review, some electrochemical methods about the detection of mycotoxins are presented with the objective to review and updated information of the methods employed to detect mycotoxins besides to know the regulation of the limits of mycotoxins in food.
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Construction and evaluation of a carbon paste electrode modified with polyaniline-co-poly(dithiodianiline) for enhanced stripping voltammetric determination of metal ions
(Univerzita Pardubice, 2014) Somerset, Vernon; Silwana, Bongiwe; Horst, Charlton van der; Iwuoha, Emmanuel
A modified carbon paste electrodes (MCPE) have been prepared in this study as an alternative “mercury-free” electrochemical sensor for the determination of Pb2+ and Cd2+ metal ions in aqueous solutions. CPE containing a conducting copolymer of polyaniline-co-poly(2,2'- dithiodianiline) (PANI-co-PDTDA) was used as a modified substrate transducer to achieve enhanced selectivity in stripping voltammetric analysis. The experimental conditions optimised included the supporting electrolyte pH, deposition potential (Ed) and time (td), set at −0.6 V vs. ref. for Pb2+ and −0.8 V for Cd2+; both kept for td = 120 s. The results with the CPE/PANI-co- PDTDA sensor have revealed the linear range within the range of 0.15 – 0.5 μg/L for Pb2+ and the same interval for Cd2+. Finally, the electrode of interest, CPE/PANI-co-PDTDA, can be characterised by the LODs of 0.03 and 0.09 μg/L for Pb2+ and Cd2+ respectively.
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Determination of insulin using a pretreated pencil graphite electrode
(Univerzita Pardubice, 2014) Vu, Dai Long; Ertek, Bensu; Červenka, Libor; Dilgin, Yusuf
In this paper, pretreated pencil graphite electrode (Pre-PGE) was used for the determination of insulin by anodic stripping differential pulse voltammetry (DPASV). The influences of the pretreatment procedures, pH values, accumulation potential and time on the signal enhancement of insulin were optimized, and a novel electrochemical method for the determination of insulin was described. The currents obtained from DPASV measurements at optimum conditions (phosphate buffer solution pH 7.0), accumulation time (60 seconds), applied potential 400 mV vs. Ag/AgCl/3.0 mol L−1 KCl) were linearly correlated with the concentration of insulin. Calibration curve was obtained for insulin concentrations in the range of 5.0-200.0×10-9 mol L−1 .The limit of detection was found to be 2.0×10-9 mol L−1.
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Development and characterization of layer-by-layer biosensors based on PEI(+)/GOx(-) layers using label-free methods
(Univerzita Pardubice, 2014) David, Melinda; Florescu, Monica; Barsan, Madalina M.; Tugulea, Laura; Brett, Christopher M. A.
Biosensors, as analytical devices, demonstrate unique efficiency in translating biochemical events into easily measurable electrical signals by using biological recognition elements, especially enzymes. Of the possible enzyme immobilisation methods, the layer-by-layer (LBL) technique, based on electrostatic interactions between layers, has the advantages of low cost, using small amount of materials, and leads to the formation of highly ordered and reproducible biosensor architectures. In this study, LbL biosensor construction has been evaluated. The substrates used were Au surfaces and mediated carbon-ink screen-printed electrodes. The gold electrodes were first functionalized with amino moieties by covalent linkage of cysteamine (Cys) through Au-S bonds. These allowed the linking of polyethyleneimine (PEI) through hydrogen-bonding to the gold surface and increased the stability of subsequent multilayers. PEI was directly adsorbed on the SPE surface. PEI is a short chain polymer and thence an efficient electron carrier, and being positively charged, it allows the formation of LBL structures with negatively charged enzymes. The multilayer formation of PEI(+)/GOx(-) was monitored by cyclic voltammetry, electrochemical impedance spectroscopy, and gravimetry. The influence of each enzymatic layer on the performance of the developed biosensor was analysed by fixed potential amperometric measurements.
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Development of a laccase biosensor for determination of Phenolic micropollutants in surface waters
(Univerzita Pardubice, 2014) Souza Gil, Eric de; Rezende, Stefani Garcia; Júnior, Eli José Miranda Ribeiro; Barcelos, Hernane Toledo; Scalize, Paulo Sérgio; Santiago, Mariangela Fontes; Quintino, Michelle Pereira; Somerset, Vernon Sydwill
Laccase is a poliphenoloxidase enzyme that catalyzes the oxidation of phenolic compounds in the corresponding quinones. The current obtained in this redox process can be used for quantitative analysis. In this work, a carbon paste biosensor modified gluteraldehyde functionalized silica and an enzymatic extract of the Pycnoporus sanguineus fungi as a lacase source is proposed for phenol determination. The effect of carbon paste and electrolyte composition, pH from 3.0 to 8.0, start potential from 0.55 to 0.25 mV, scan rate from 5 to 25 mV s-1 and potential pulse amplitude from 10 to 60 mV on the differential pulse voltammetric response was investigated. A linear correlation of r² = 0.9946 was obtained for the phenol content (catechol) in the concentration range from 50 to 500 nmol L-1, with a detection limit of 30 nmol L-1. This biosensor was used for the determination of different kinds of phenolic compounds, presenting a better response for catechol.
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The effect of acetate buffer concentration on the anodic stripping voltammetric response of carbon paste (macro)electrodes and microelectrodes
(Univerzita Pardubice, 2014) Agrafiotou, Panagiota; Soukupová, Lucie; Švancara, Ivan; Sotiropoulos, Sotiris
The Square Wave Anodic Stripping Voltammetry response of in situ deposited Bi-film conventional size Carbon Paste Electrodes (CPEs) and generic microdisc carbon paste microelectrodes (CPμEs) in Pb(II) and Cd(II) solutions, has been studied as a function of acetate buffer concentration in the extended 0.001 M -0.5 M range. The advantages of microelectrodes (high ohmic tolerance and high mass transfer rates) allowed for the recording of good quality voltammograms at the CPμEs even at the lowest 0.001 M acetate levels studied, resulted in relatively higher voltammetric peaks and gave an optimum Pb and Cd signal in the 0.01-0.02 M acetate range.
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Electrochemical behavior of triethanolamine at a carbon paste electrode
(Univerzita Pardubice, 2014) Karastogianni, Sophia; Girousi, Stella
In this article, the electrochemical behavior of triethanolimine is described with a carbon paste electrode. A differential pulse voltammetric method was also developed for the determination of triethanolamine as an application to electroanalysis at a carbon paste electrode. The resultant voltammograms have revealed the irreversible electrochemical process that can be utilized to quantify the substances of interest, for triethanolamine, for which the detection limit (3σ) was estimated to be 2.8 × 10−5 mol L−1.
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Electrochemical impedance spectroscopy investigations focused on food allergens
(Univerzita Pardubice, 2014) Vasilescu, Alina; Vezeanu, Alis; Badea, Mihaela
In this article, we survey recent literature related to the development of impedimetric sensors and methods for allergen proteins in food. Electrochemical impedance spectroscopy is an electrochemical method that allows label-free monitoring of analyte-ligand interactions and was largely used for characterising various steps in the development of (bio)sensors. Both faradaic impedance spectroscopy – using a redox probe added to the analytical system to be investigated – and non-faradaic impedance spectroscopy were used for the detection of food allergens. Several approaches leading to high sensitivity and application to the analysis of real samples are particularly emphasized. The challenges in using EIS for the determination of allergens are discussed.
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Electrochemical investigation of hazardous metals released from fly ash
(Univerzita Pardubice, 2014) Królicka, Agnieszka; Bobrowski, Andrzej
The paper discusses the utilization of stripping voltammetric methods for the determination of Zn, Pb, Cr, Co and Ni in extracts from fly ashes. For this purpose, the most sensitive anodic stripping voltammetric (ASV) procedure for Zn and Pb quantification in acetic buffer has been selected. Traces of Ni, Co and Cr(VI) were determined by means of catalyticadsorptive stripping voltammetry (CAdSV) with nioxime and nitrite (Ni and Co) or with DTPA and nitrate (Cr). It was observed that relatively high amounts of surface-active substances or other dissolved organic matter (DOM) present in the extracts severely interfered in the determination of the investigated metals ions by blocking the electrode surface and suppressing the stripping voltammetric response of metal ions, especially in ASV. Therefore, the methods of destroying DOM using ultraviolet irradiation or through their in situ removal via adsorption on the Amberlite XAD-7HP resin were examined and applied.
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Electrochemical sensor for histamine determination based on zinc oxide thin films electrodeposited on carbon paste electrodes
(Univerzita Pardubice, 2014) Pekec, Bruna; Hauser, Susanne; Kalcher, Kurt; Ortner, Astrid
Histamine, a biogenic amine and important mediator of inflammation was quantitatively analysed using electrochemical techniques. The sensor designed in this context based on carbon paste (CP) as electrode material and zinc oxide (ZnO) as modifier to increase the selectivity, due to the strong complex building tendency of the imidazole ring to metals. Using an alkaline electrolyte medium the oxidation potential was shifted from + 1.20 V in neutral medium to a less positive value of + 0.750 V vs. Ag/AgCl. A logarithmic correlation for a concentration range from 5 to 500 μg/mL could be found. The developed ZnO-CP based sensor, characterized by a precision (R.S.D.) of 5.8 % and an accuracy of 5.2 % was successfully tested in complex food matrix.
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Electrodes modified with bismuth, antimony and tin precursor compounds for electrochemical stripping analysis of trace metals (a short review)
(Univerzita Pardubice, 2014) Lezi, Nikolitsa; Economou, Anastasios; Barek, Jiří
Over the last decade, intensive research is being carried out towards the development of “green” electrochemical sensors. Bismuth, antimony and tin electrodes have been proposed as potential substitutes of mercury electrodes in electrochemical stripping analysis of trace metals. The main advantage of these metals as electrode materials is their lower toxicity compared to mercury. Among the different configuration of bismuth, antimony and tin electrodes, one of the most attractive involves the modification of a support material with a bismuth, antimony or tin precursor compound (oxide, hydroxide or sparingly soluble salt). When the electrode is polarized to a sufficiently cathodic potential, the metal precursor is reduced to the respective metal which forms a thin “film” on the surface of the support material. The present article is an overview of the existing state–of–the–art in the field of bismuth, antimony and tin precursor–modified sensors. This review covers and critically discusses the various fabrication approaches (support materials, types of precursor compounds, modification approaches, precursor reduction methods) and also lists typical applications of these precursor–modified sensors to electrochemical stripping analysis of metals.
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New applications of carbon paste electrodes for determination of biologically active organic compoun
(Univerzita Pardubice, 2014) Zima, Jiří; Barek, Jiří; Dejmková, Hana; Wang, Joseph
In this paper, new electrochemical determinations of selected biologically active compounds are described employing various types of carbon paste electrodes (CPE) in batch voltammetric methods (differential pulse voltammetry (DPV), direct current voltammetry (DCV), and cyclic voltammetry (CV)) and in HPLC with electrochemical detection (HPLC-ED) utilizing amperometric CPE sensors. The results for determination of cymoxanil, famoxadone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, chlortoluron, carboxin, triclosan, diafenthiuron, and propyl gallate are compared and discussed. Glassy carbon spherical microparticles were used as carbonaceous component of the paste. The limits of detection of some analytes were below 1·10-7 mol l-1 in both batch and flow methods. The newly developed methods of determination were applied to model samples of drinking and river water, soils, and practical samples of edible oil, toothpaste, soap, and toilet water.
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Non-traditional electrode materials for detection of biomarkers
(Univerzita Pardubice, 2014) Barek, Jiří; Moreira, Josino C.; Wang, Joseph
In this paper, new electrochemical methods suitable for detection of various types of biomarkers (biomarkers of exposition, tumor biomarkers, and biomarkers of medical treatment) are briefly reviewed. Attention is paid to the use of non-traditional electrode materials (various forms of amalgam electrodes, boron doped diamond film electrodes, carbon paste and carbon film electrodes, etc.) for voltammetric (batch analysis) and amperometric (flowing systems) detection of above mentioned biomarkers.
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On the performance of amperometric tyrosinase carbon paste biosensor in the presence of catechol, resorcinol, or hydroquinone
(Univerzita Pardubice, 2014) Sýs, Milan; Metelka, Radovan; Vytřas, Karel
This study was aimed to understand which substitution position of hydroxy groups on benzene ring is the most suitable for active site of enzyme tyrosinase, and also to determine if tyrosinase is a useful biological component for the development a biosensor based on carbon material for the determination of polyphenolic compounds in food samples. Electrochemical properties of diphenols (catechol, resorcinol, and hydroquinone) at bare carbon paste electrode (CPE) and CPE surface-modified with conductive copolymer Nafion and enzyme mushroom tyrosinase (CPE/Tyr/Nafion) were investigated using cyclic voltammetry and hydrodynamic amperometry.
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Possibilities of voltammetric determination of pyridine herbicide picloram using boron-doped diamond electrodes
(Univerzita Pardubice, 2014) Bandžuchová, Lenka; Švorc, Ľubomír; Vojs, Marian; Marton, Marián; Michniak, Pavol; Chýlková, Jaromíra
Voltammetric behavior of a wide-spread used pyridine herbicide picloram (PCR) was investigated using two different types of boron-doped diamond working electrodes: commercial available and self-assembled. PCR provided one irreversible oxidation peak in an acidic medium occurring at very positive potential (about +1.5 V vs. Ag/AgCl/ 3 mol L−1 KCl) in both cases. 1 mol L−1 sulfuric acid was selected as the most suitable supporting electrolyte for electrochemical oxidation of PCR. Differential pulse voltammetric methodology was elaborated and its operating parameters were optimized to achieve the best analytical performance for determination of PCR. Both working electrodes provided high repeatability, wide linear concentration range and low limit of detection. Applicability of proposed method was verified by analysis of PCR in model samples of tap and natural waters and human urine, respectively.
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Possible errors in electrochemical detection of blood glucose
(Univerzita Pardubice, 2014) Badea, Mihaela; Pascu, Alina Mihaela; Nicolae, Ramona Alexandra; Taus, Nicoleta; Nunes, Gilvanda Silva; Moga, Marius Alexandru
The need of dosage of glucose concentration required to develop test methods that allow rapid and accessible even at home. It is necessary to follow a simple protocol that minimizes errors and interferences using some functions of these devices. We have identified possible errors in obtaining experimental data: lower sample volume, consume of different foods in the evening and the morning of blood collection, type of sample analysed (serum/plasma, venous/capillary blood). The data obtained using commercial biosensors were compared with spectrometric methods and good report was obtained.
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Probiotics in medicine and methods with electrochemical detection
(Univerzita Pardubice, 2014) Badea, Mihaela; Veregut, Veronica; Popescu, Bettina; Popovici, Bianca; Mitrica, Maria; Neica, Ligia; Nunes, Gilvanda Silva; Moga, Marius
Preventing diseases from diarrhea to cancer, probiotics are used on different food products. Electronic tongues (e-tongues) were developed for complex matrices as food products. These new methods combine electrochemical devices (amperometric, potentiometric, impedimetric) and have as additional advantages to be fast and convenient for field an in situ analysis, being used with good qualitative and (semi)quantitative results also in the place were food products are (at the manufactures, in stores, in storage places).