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Relevant bibliographies by topics / PH-potentiometry

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Academic literature on the topic 'PH-potentiometry'

Author: Grafiati

Published: 4 June 2021

Last updated: 8 February 2022

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Journal articles on the topic "PH-potentiometry"

1

Ma, Ming Ming, Zhi Tong, and Yong Wen. "Poly Silk Peptide Film PH Sensor Based on Zero Current Potentiometry." Advanced Materials Research 450-451 (January 2012): 554–56. http://dx.doi.org/10.4028/www.scientific.net/amr.450-451.554.

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A poly silk peptide film pH sensor has been developed using zero current potentiometry system. A poly silk peptide film coated pencil graphite electrode is connected in series between the working and counter electrodes of a potentiostat, and immersed in solution together with a reference electrode. When the solution pH varies, the resulting zero current potentiometry is linear with the values of the solution pH in the range of 1.81 to 11.58. This pH sensor shows high stability, accuracy, selectivity and reproduction.

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2

Zimmermann, Peter, Andreas Weltin, Gerald Urban, and Jochen Kieninger. "Active Potentiometry for Dissolved Oxygen Monitoring with Platinum Electrodes." Sensors 18, no. 8 (July 24, 2018): 2404. http://dx.doi.org/10.3390/s18082404.

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Potentiometric oxygen monitoring using platinum as the electrode material was enabled by the combination of conventional potentiometry with active prepolarization protocols, what we call active potentiometry. The obtained logarithmic transfer function is well-suited for the measurement of dissolved oxygen in biomedical applications, as the physiological oxygen concentration typically varies over several decades. We describe the application of active potentiometry in phosphate buffered salt solution at different pH and ion strength. Sensitivity was in the range of 60 mV/dec oxygen concentration; the transfer function deviated from logarithmic behavior for smaller oxygen concentration and higher ion strength of the electrolyte. Long-term stability was demonstrated for 60 h. Based on these measurement results and additional cyclic voltammetry investigations a model is discussed to explain the potential forming mechanism. The described method of active potentiometry is applicable to many different potentiometric sensors possibly enhancing sensitivity or selectivity for a specific parameter.

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Ma, Ming Ming, Zhi Tong, and Yong Wen. "Poly Silk Peptide Film PH Sensor Based on Zero Current Potentiometry." Advanced Materials Research 450-451 (January 2012): 554–56. http://dx.doi.org/10.4028/scientific5/amr.450-451.554.

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4

Kay, C. J., M. J. Barber, B. A. Notton, and L. P. Solomonson. "Oxidation–reduction midpoint potentials of the flavin, haem and Mo-pterin centres in spinach (Spinacia oleracea L.) nitrate reductase." Biochemical Journal 263, no. 1 (October 1, 1989): 285–87. http://dx.doi.org/10.1042/bj2630285.

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Oxidation-reduction midpoint potentials have been determined for the flavin, cytochrome b557 and Mo-pterin prosthetic groups of spinach (Spinacia oleracea L.) assimilatory nitrate reductase using visible, c.d. and room-temperature e.p.r. potentiometric titrations. At pH 7 and 25 degrees C, the midpoint potential for the FAD/FADH2 couple was determined by c.d. potentiometry to be -280 +/- 10 mV (n = 2). The redox potential for reduction of the haem was determined by visible potentiometry to be -123 +/- 10 mV (n = 1), significantly lower than the previously published value of -60 mV [Fido, Hewitt, Notton, Jones & Nasrulhaq-Boyce (1979) FEBS Lett. 99, 180-182]. Potentials for the Mo(VI)/Mo(V) and Mo(V)/Mo(IV) redox couples, determined by room-temperature e.p.r. potentiometry, were found to be +2 +/- 20 and -6 +/- 20 mV respectively. These values are very similar to the values previously determined for the FAD, haem and Mo-pterin centres in assimilatory nitrate reductase isolated from the unicellular green alga Chlorella vulgaris and indicate a close thermodynamic similarity between the two enzymes.

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5

Gonzalez, Samantha Lemke, Regina Cristina Aparecida Lima, Eliana Beleski Borba Carneiro, Mareci Mendes de Almeida, and Neiva Deliberali Rosso. "Pectin methylesterase activity determined by different methods and thermal inactivation of exogenous pme in mango juice." Ciência e Agrotecnologia 35, no. 5 (October 2011): 987–94. http://dx.doi.org/10.1590/s1413-70542011000500017.

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Pectin methylesterase (PME) hydrolyzes methyl ester groups in pectin chains to form carboxylic groups, releasing methanol and H3O+. The aim of this study was to determine PME activity in samples of pectinases by UV-VIS spectroscopy, to measure the acid and methanol produced in the reaction of pectin with pectinase and to verify the thermal inactivation of exogenous PME in mango juice. The activity of PME in samples of pectinase was determined by potentiometry, UV-VIS spectroscopy, and by the action of alcohol oxidase. The reaction showed greater activity at pH 4.0 to 4.5 and at a temperature of 45° C. PME activity determined by UV-VIS spectroscopy with bromophenol blue indicator showed a good correlation with the activity determined by potentiometry and with alcohol oxidase. The results showed that bromophenol blue indicators can be used to determine PME activity in samples of pectinases where the optimum pH is located in the acidic range. The thermal inactivation of exogenous PME in mango juice occurred at 75° C for 20 min of exposure.

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Etienne, Mathieu, Paul Dierkes, Thomas Erichsen, Wolfgang Schuhmann, and Ingrid Fritsch. "Constant-Distance Mode Scanning Potentiometry. High Resolution pH Measurements in Three-Dimensions." Electroanalysis 19, no. 2-3 (January 2007): 318–23. http://dx.doi.org/10.1002/elan.200603735.

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7

Natedungta, W., and W. Prissanaroon-Ouajai. "All-Solid-State pH Sensor Based on Conducting Polymer." Advanced Materials Research 93-94 (January 2010): 591–94. http://dx.doi.org/10.4028/www.scientific.net/amr.93-94.591.

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A solid-state (free of internal electrolyte solution) reference electrode based on metallic silver is simply fabricated via a simple electrodeposition from AgNO3. Potentiometry is carried out to study the performance of the solid-state reference electrode in comparison with the commercial Ag/AgCl reference electrode. In addition, the proposed solid-state reference electrode has been integrated with the PPy-modified pH electrode to form an all-solid-state pH sensor, showing the capability of pH measurement. Absence of the internal solution leads to the pH sensor that is convenient to use and maintenance. In addition, the proposed pH sensor is possibly applied to biochemical and medical processes as well as flow infection analysis.

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8

Shehatta, I., I. Kenawy, A. H. Askalany, and Ayman A. Hassan. "Thermodynamic of metal complexation of the macrocyclic antibiotic rifampicin." Canadian Journal of Chemistry 79, no. 1 (January 1, 2001): 42–49. http://dx.doi.org/10.1139/v00-172.

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The acid-base and complexation equilibria of rifampicin with H+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, and Pb2+ were studied by means of potentiometry. The stoichiometric equilibrium constants were determined in 50% (v/v) methanol-water medium at different temperatures and constant ionic strength (0.05 M KCl). It was established that rifampicin has two proton-binding sites. The distribution diagram of the corresponding ionic species as a function of pH is given and indicated that rifampicin exists predominantly in the zwitterionic form at pH [Formula: see text] 5. The thermodynamic parameters of protonation and complexation were derived and discussed. The formation of the complexes is spontaneous, more favourable at lower temperatures, entropically unfavourable, and an enthalpy-driven process. The order of the changes in Gibbs energy and enthalpy accompanying the complexation was found to be Mn2+ < Co2+ < Ni2+ < Cu2+ > Pb2+ > Zn2+ > Cd2+ > Hg2+ in accordance with the well-known sequence of Irving and Williams. The transition series contraction energy (Er(Mn-Zn)), and the ligand field stabilization energy (δH) were calculated from the enthalpy changes.Key words: rifampicin, thermodynamics, potentiometry, and complexation.

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9

Gao, Zhu Qing, Xiao Dong Cai, Lei Lei Cheng, and Kai Cheng Ling. "Studies on the Coordination Reactions of Polyphenols and Vanadium (IV) Using pH-Potentiometry." Advanced Materials Research 396-398 (November 2011): 2225–29. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.2225.

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Protonation constants of pyrocatechol, pyrogallol and gallic acid, and stability constants, thermodynamic properties of their complexes with tetravalent vanadium VO2+ have been calculated by using pH-potentiometry at different temperatures and ionic strength of 0.1mol•L-1NaCl. The results indicated protonation constants and stability constants decrease with increasing temperature. Higher temperature is unfavorable to the complexation reactions. This kind of reaction is exothermic reaction that was spontaneous. Compared with all thermodynamic properties, the enthalpy change is the driving force for the reaction.

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10

Lefèvre, G., and G. Berger. "Potentiometry up to 275°C: Example of pH titrations of cobalt ferrite particles." Journal of Colloid and Interface Science 430 (September 2014): 12–17. http://dx.doi.org/10.1016/j.jcis.2014.05.017.

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More sources

Dissertations / Theses on the topic "PH-potentiometry"

1

Koort, Eve. "Uncertainty estimation of potentiometrically measured pH and pK[subscript a] values /." Online version, 2006. http://dspace.utlib.ee/dspace/bitstream/10062/599/5/koorteve.pdf.

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Iwazaki, Alexandra. "Estudo da influência da força iônica na medição de H+ utilizando eletrodo de membrana de vidro." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-21092018-095836/.

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O presente trabalho mostra a influência da força iônica na leitura potenciométrica de pH de soluções aquosas utilizando membrana de vidro. O tamanho e a carga dos íons são importantes fatos apontados. Um tipo de efeito de \"memória\" aparece durante as leituras de pH, este foi contornado pela calibração multipontuada. Propostas para corrigir a influência da força iônica foram estudadas sob aspectos experimental e teórico. A teoria de Cheng sobre o mecanismo de ação da membrana de vidro como capacitor químico foi comprovada por estudos em que se variou a ação do campo elétrico. O conceito da grandeza de pH também foi discutido.
This work shows the influence of the ionic strength on the potenciometric measurements of pH of aqueous solutions using the electrode of glass membrane. The size and charge of the ions are important studied facts. One type of \"memory\" of glass membrane was observed and this effect was overcame using multipoint calibration. To correct the influence of the ionic strength two studies on experimental and theorical aspects were performed. The model proposed by Cheng to the mechanism of glass membrane as a chemical capacitor was confirmed by application of electrical field on the glass membrane. The concept of pH amount was discussed.

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3

RACAPE, EVELYNE. "Influence des fonctions amides sur les proprietes physicochimiques des pectines." Nantes, 1989. http://www.theses.fr/1989NANT2001.

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Gelification des pectines amidees en presence de calcium. Etude de modeles simplifies (acides pectiques amides). Les pko dependent du parametre de densite de charge et non pas du taux d'amidation/repartition non aleatoire des fonctions amides. La sensibilite au calcium des pectines amidees resulte de l'alternance de blocs de fonctions acides libres et methyles reparties aleatoirement et de fonctions amides, generateurs de liaisons h intermoleculaires, provenant de leur synthese concentre en ammoniac et en pectine

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4

Seifert, Steffen. "Synthese und Komplexbildungseigenschaften ausgewählter Maillard-Reaktionsprodukte." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1232923513056-87374.

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Zahlreiche Studien belegen, dass Maillard-Reaktionsprodukte (MRP) in vivo einen Einfluss auf den physiologischen Metallionenhaushalt haben können. Da bisher noch keine Korrelation zwischen dem Entstehen von definierten MRP und einem erhöhten Metallionenbindungsvermögen ermittelt werden konnte, war es das Ziel dieser Arbeit, die Komplexbildungseigenschaften der ausgewählten MRP Nε-Carboxymethyllysin, Isomaltol und Maltosin sowie deren Strukturanaloga Maltol, Deferipron, Mimosin und Pyridosin mit den physiologisch relevanten Metallionen Cu(II), Zn(II), Fe(III), Al(III) und Mn(II) zu untersuchen. Dazu wurden die MRP Nε-Carboxymethyllysin und Maltosin sowie die parallel untersuchten Substanzen Pyridosin, Maltosin-3-benzylether, Nα-Hippuryl- und Nα-Acetylmaltosin in ausreichender Menge und Reinheit synthetisiert. Dabei gelang es, für Maltosin und Pyridosin neue und effiziente Synthesewege zu entwickeln, bei welchen zum ersten Mal beide Substanzen gezielt aufgebaut wurden. Die Komplexbildungskonstanten der Liganden mit den Metallionen wurden pH-potentiometrisch bestimmt (I[KNO3] = 0,15 M; θ = 25 °C). Durch die Auswertung der Protonierungskonstanten der gebildeten Komplexe und das Vermessen geeigneter Derivate konnten für die untersuchten Komplexe zusätzlich die Koordinationsstellen der Liganden aufgeklärt werden. Die Untersuchungen zu den Komplexbildungseigenschaften bestätigten erstmals die Vermutung, dass MRP in der Lage sind, Metallionen zu binden. Dabei wurde weiterhin ermittelt, dass die Bindung von Cu(II) durch Nε-Carboxymethyllysin und von Fe(III), Al(III) und Cu(II) durch Maltosin durchaus von physiologischer Relevanz sind. Die Bedeutung der Ergebnisse wurde qualitativ durch Versuche mit Maltosin-derivatisiertem Rinderserumalbumin unterstrichen. Als besonderes Ergebnis der Arbeit ist herauszustellen, dass das MRP Maltosin und die Verbindung Pyridosin deutlich stabilere Komplexe mit Fe(III) bilden als das zur Fe(III)-Chelattherapie eingesetzte Medikament Deferipron. Diese festgestellte Eigenschaft bietet interessante Perspektiven für zukünftige Studien zur möglichen Anwendung von z. B. Maltosin als Pharmakon
Several studies show that Maillard reaction products (MRP) may influence the physiological metal ion balance. But none of these studies prove a correlation between the formation of defined MRP and an enhanced metal ion binding. Therefore it was the aim of this work to investigate the complex formation characteristics of the selected MRP Nε-carboxymethyllysine, isomaltol and maltosine as well as the structural analogues maltol, deferiprone, mimosine and pyridosine with the physiological relevant metal ions Cu(II), Zn(II), Fe(III), Al(III) and Mn(II). For that purpose the MRP Nε-carboxymethyllysine and maltosine plus the parallel analysed substances pyridosine, maltosine-3-benzylether, Nα-hippuryl- and Nα-acetylmaltosine were synthesised. Thereby new and efficient syntheses for maltosine and pyridosine were developed. The stability constants of the ligands with the metal ions were determined by pH-potentiometry (I(KNO3) = 0,15 M; θ = 25 °C). Furthermore the donor atoms within the formed complexes were determined by the evaluation of the protonation constants of the formed complexes and by the analysis of adequate derivatives. The studies to the complex formation characteristics confirm for the first time the assumption, that MRP are able to form stable complexes with metal ions. Withal it was ascertained that the coordination of Cu(II) by Nε-carboxymethyllysine and of Fe(III), Al(III) and Cu(II) by maltosine may be of physiological relevance. The significance of the results was pointed out by experiments with maltosine derivatised bovine serum albumine. The fact that the MRP maltosine and the compound pyridosine form more stable complexes with Fe(III) as the medicament for the Fe(III) chelate therapy deferiprone is a particular result of this work. This property affords interesting perspectives for future studies about a possible appliance of e.g. maltosine as pharmaceutical

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5

Seifert, Steffen. "Synthese und Komplexbildungseigenschaften ausgewählter Maillard-Reaktionsprodukte." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23758.

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Zahlreiche Studien belegen, dass Maillard-Reaktionsprodukte (MRP) in vivo einen Einfluss auf den physiologischen Metallionenhaushalt haben können. Da bisher noch keine Korrelation zwischen dem Entstehen von definierten MRP und einem erhöhten Metallionenbindungsvermögen ermittelt werden konnte, war es das Ziel dieser Arbeit, die Komplexbildungseigenschaften der ausgewählten MRP Nε-Carboxymethyllysin, Isomaltol und Maltosin sowie deren Strukturanaloga Maltol, Deferipron, Mimosin und Pyridosin mit den physiologisch relevanten Metallionen Cu(II), Zn(II), Fe(III), Al(III) und Mn(II) zu untersuchen. Dazu wurden die MRP Nε-Carboxymethyllysin und Maltosin sowie die parallel untersuchten Substanzen Pyridosin, Maltosin-3-benzylether, Nα-Hippuryl- und Nα-Acetylmaltosin in ausreichender Menge und Reinheit synthetisiert. Dabei gelang es, für Maltosin und Pyridosin neue und effiziente Synthesewege zu entwickeln, bei welchen zum ersten Mal beide Substanzen gezielt aufgebaut wurden. Die Komplexbildungskonstanten der Liganden mit den Metallionen wurden pH-potentiometrisch bestimmt (I[KNO3] = 0,15 M; θ = 25 °C). Durch die Auswertung der Protonierungskonstanten der gebildeten Komplexe und das Vermessen geeigneter Derivate konnten für die untersuchten Komplexe zusätzlich die Koordinationsstellen der Liganden aufgeklärt werden. Die Untersuchungen zu den Komplexbildungseigenschaften bestätigten erstmals die Vermutung, dass MRP in der Lage sind, Metallionen zu binden. Dabei wurde weiterhin ermittelt, dass die Bindung von Cu(II) durch Nε-Carboxymethyllysin und von Fe(III), Al(III) und Cu(II) durch Maltosin durchaus von physiologischer Relevanz sind. Die Bedeutung der Ergebnisse wurde qualitativ durch Versuche mit Maltosin-derivatisiertem Rinderserumalbumin unterstrichen. Als besonderes Ergebnis der Arbeit ist herauszustellen, dass das MRP Maltosin und die Verbindung Pyridosin deutlich stabilere Komplexe mit Fe(III) bilden als das zur Fe(III)-Chelattherapie eingesetzte Medikament Deferipron. Diese festgestellte Eigenschaft bietet interessante Perspektiven für zukünftige Studien zur möglichen Anwendung von z. B. Maltosin als Pharmakon.
Several studies show that Maillard reaction products (MRP) may influence the physiological metal ion balance. But none of these studies prove a correlation between the formation of defined MRP and an enhanced metal ion binding. Therefore it was the aim of this work to investigate the complex formation characteristics of the selected MRP Nε-carboxymethyllysine, isomaltol and maltosine as well as the structural analogues maltol, deferiprone, mimosine and pyridosine with the physiological relevant metal ions Cu(II), Zn(II), Fe(III), Al(III) and Mn(II). For that purpose the MRP Nε-carboxymethyllysine and maltosine plus the parallel analysed substances pyridosine, maltosine-3-benzylether, Nα-hippuryl- and Nα-acetylmaltosine were synthesised. Thereby new and efficient syntheses for maltosine and pyridosine were developed. The stability constants of the ligands with the metal ions were determined by pH-potentiometry (I(KNO3) = 0,15 M; θ = 25 °C). Furthermore the donor atoms within the formed complexes were determined by the evaluation of the protonation constants of the formed complexes and by the analysis of adequate derivatives. The studies to the complex formation characteristics confirm for the first time the assumption, that MRP are able to form stable complexes with metal ions. Withal it was ascertained that the coordination of Cu(II) by Nε-carboxymethyllysine and of Fe(III), Al(III) and Cu(II) by maltosine may be of physiological relevance. The significance of the results was pointed out by experiments with maltosine derivatised bovine serum albumine. The fact that the MRP maltosine and the compound pyridosine form more stable complexes with Fe(III) as the medicament for the Fe(III) chelate therapy deferiprone is a particular result of this work. This property affords interesting perspectives for future studies about a possible appliance of e.g. maltosine as pharmaceutical.

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Book chapters on the topic "PH-potentiometry"

1

Marple, Ronita L., and William R. LaCourse. "Potentiometry: pH and Ion-Selective Electrodes." In Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 491–508. Fourth edition / [edited by] Nelu Grinberg, Sonia Rodriguez. | Boca Raton : CRC Press, Taylor & Francis Group, 2019.: CRC Press, 2019. http://dx.doi.org/10.1201/9781315118024-16.

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"Potentiometry: pH and Ion-Selective Electrodes." In Analytical Instrumentation Handbook, 535–54. CRC Press, 2004. http://dx.doi.org/10.1201/9780849390395-19.

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3

Fawcett, W. Ronald. "Charge Transfer Equilibria at Interfaces." In Liquids, Solutions, and Interfaces. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195094329.003.0013.

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Processes in which charge is transferred from one phase to another at an interface make up an important class of interfacial reactions. Well-known examples are the reactions which occur at the electrodes of an electrochemical cell. These are electron transfer reactions, oxidation taking place at one electrode and reduction at the other. The early study of electrochemical cells provided valuable thermodynamic information about the redox processes occurring in them. When an electrochemical cell is a source of energy, for example, a battery, chemical energy is converted to electrical energy. When electrical energy is driven into an electrochemical cell from an external source, electrode reactions producing products of commercial interest are possible. Thus the general subject discussed here is of considerable practical importance. Another important class of interfacial charge transfer processes occurs at the membrane | solution interface. Some solute species can move into the membrane phase, whereas others cannot. When ions are involved in membrane selectivity, a potential drop is established at the interface. Ion transfer processes at membranes are extremely important in living organisms and form the basis for the functioning of the nervous system. Membranes are also involved in ion selective electrodes such as the ubiquitous pH electrode. These electrodes are often used in modern analytical techniques based on potentiometry. In the present chapter, the relationship between the electrode potential and the activity of the solution components in the cell is examined in detail. The connection between the Galvani potential difference at the electrode solution interface and the electrode potential on the standard redox scale is discussed. This leads to an examination of the extrathermodynamic assumption which allows one to define an absolute electrode potential. Ion transfer processes at the membrane | solution interface are then examined. Diffusion potentials within the membrane and the Donnan potentials at the interface are illustrated for both liquid and solid state membranes. Specific ion electrodes are described, and their various modes of sensing ion activities in an analyte solution discussed. The structure and type of membrane used are considered with respect to its selectivity to a particular ion over other ions.

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