Articoli di riviste: "Potentiometry"

1

Braun, R. D. "Potentiometry and potentiometric titrations". TrAC Trends in Analytical Chemistry 4, n. 5 (maggio 1985): xxi. http://dx.doi.org/10.1016/0165-9936(85)87014-x.

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2

Zimmermann, Peter, Andreas Weltin, Gerald Urban e Jochen Kieninger. "Active Potentiometry for Dissolved Oxygen Monitoring with Platinum Electrodes". Sensors 18, n. 8 (24 luglio 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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3

Nagels, L. J. "Potentiometric detection for high-performance liquid chromatography is a reality: Which classes of organic substances are the targets?" Pure and Applied Chemistry 76, n. 4 (1 gennaio 2004): 839–45. http://dx.doi.org/10.1351/pac200476040839.

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Potentiometric detection in high-performance liquid chromatography (HPLC) is shown to be an underexploited technique. The technique can be of great use to less classical potentiometry targets, such as bioorganics, of low as well as of high molecular weight. The understanding of non-faradaic potentiometry is, however, still problematic. Predicting the selectivity and sensitivity of a potentiometric electrode for organic ionizable substances can be done to a certain extent using QSAR methods. Although many new polymer materials and synthetic receptor molecules for organic ionics are being synthesized, few of them are applied in potentiometric membrane coatings. Hydrophilic organics form an interesting target group for these new materials.

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4

Sheet, Partha Sarathi, Suji Park, Pavel Sengupta e Dipankar Koley. "Multifunctional dendritic molecular probe for selective detection of Cu²⁺ ions using potentiometric and fluorometric techniques". Analyst 146, n. 23 (2021): 7109–17. http://dx.doi.org/10.1039/d1an01417j.

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We have designed and synthesized a multifunctional dendritic molecular probe that selectively detects Cu2+ ions via potentiometric and fluorometric techniques with low detection limits (3.5 μM in potentiometry, 15 nM in fluorometry).

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5

Janata, Jiří. "Potentiometry in gas phase". Collection of Czechoslovak Chemical Communications 74, n. 11-12 (2009): 1623–34. http://dx.doi.org/10.1135/cccc2009101.

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In order to yield analytically useful information every potentiometric measurement requires stable and reproducible reference potential. That requirement has to be satisfied for potentiometry performed in liquid or gas phase alike, although two fundamentally different mechanisms lead to formation of the measurable cell voltage. It is shown that the Fermi level of silicon used in insulated gate field-effect transistors (IGFET) provides an exceptionally stable and robust reference potential. A semi-quantitative dependence of IGFET output on partial pressure of the analyte gas is presented.

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Pleniceany, Maria, Marian Isvoranu e Cezar Spinu. "Liquid membrane ion-selective electrodes for potentiometric dosage of coper and nickel". Journal of the Serbian Chemical Society 70, n. 2 (2005): 269–76. http://dx.doi.org/10.2298/jsc0502269p.

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This paper presents experimental and theoretical data regarding the preparation and characterization of three liquid-membrane electrodes, which have not been mentioned in the specialized literature so far. The active substances, the solutions of which in nitrobenzene formed the membranes on a graphite rod, are simple complex combinations of Cu(II) and Ni(II) ions with an organic ligand belonging to the Schiff base class: N-[2-thienylmethilidene]-2-aminoethanol (TNAHE). The Cu2+ -selective and Ni2+ -selective electrodes were used to determine the copper and nickel ions in aqueous solutions, both by direct potentiometry and by potentiometric titration with EDTA. They were also used for the determination of Cu2+ and Ni2+ ions in industrial waters by direct potentiometry.

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Kay, C. J., M. J. Barber, B. A. Notton e 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, n. 1 (1 ottobre 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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Gerasimova, Elena, Elena Gazizullina, Sofya Kolbaczkaya e Alla Ivanova. "The Novel Potentiometric Approach to Antioxidant Capacity Assay Based on the Reaction with Stable Radical 2,2′-diphenyl-1-picrylhydrazyl". Antioxidants 11, n. 10 (1 ottobre 2022): 1974. http://dx.doi.org/10.3390/antiox11101974.

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For the first time, new possibilities of using the DPPH• as a signal-forming oxidant molecule with potentiometric detection are shown. The CV method confirmed the presence of a quasi-reversible potential-determining system DPPH•/DPPH-H under experimental conditions. This fact makes it possible to use DPPH• as the model of the oxidizing agent for obtaining an analytical signal by the potentiometry method. The potentiometric approach makes it possible to obtain the value of the Nernst slope and the antioxidant capacity in one experiment. It consists of an antioxidant supplement and two consecutive DPPH• supplements. In this case, the calculation of the Nernst slope is carried out by introducing the second addition of the oxidizing agent and constructing a calibration curve against the reaction background with an antioxidant. Solutions of individual antioxidants α-tocopherol, quercetin, (±)-catechin hydrate, and α-lipoic acid were studied by the developed approach. A high correlation with the results of spectrophotometric measurements is shown. At the same time, the potentiometry method is devoid of the concentration limitations of the spectrophotometric method, which was confirmed. In the study of plant materials extracts, a high correlation of antioxidant capacity, obtained by potentiometric and spectrophotometric methods, was shown only for objects whose color did not contribute to the DPPH• absorption. The versatility of the potentiometric method for studying objects of any color was shown.

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9

Hitchman, Michael L., e Frazier W. M. Nyasulu. "Potentiometric monitoring of proteins—part 6. Indirect potentiometry". Talanta 40, n. 9 (settembre 1993): 1449–59. http://dx.doi.org/10.1016/0039-9140(93)80225-g.

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10

Vytřas, Karel, Ivan Svancara e Radovan Metelka. "Carbon paste electrodes in electroanalytical chemistry". Journal of the Serbian Chemical Society 74, n. 10 (2009): 1021–33. http://dx.doi.org/10.2298/jsc0910021v.

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An overview is given dealing with the applications of carbon paste electrodes in equilibrium potentiometry as well as in electrochemical stripping analysis using both voltammetric and potentiometric modes. Various modifications of carbon pastes and carbon paste-based biosensors are also mentioned. The main emphasis in this article is directed at summarizing recent results of the authors' research group during the past few years.

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11

Guagnellini, E., G. Spagliardi, G. Bernardi e P. Stella. "Reliability of IL Monarch ion-selective electrode module for sodium, potassium, and chloride measurements." Clinical Chemistry 34, n. 4 (1 aprile 1988): 746–48. http://dx.doi.org/10.1093/clinchem/34.4.746.

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Abstract We evaluated the IL Monarch random-access centrifugal analyzer for measurement of Na+, K+, and Cl- by an indirect potentiometric method. For different concentrations of control material, the total precision (CV) ranged between 0.82% and 1.14% for the three electrolytes; linearity was acceptable within a range of 103 to 215 mmol/L for Na+, 1.6-15.25 mmol/L for K+, and 80-173 mmol/L for Cl-. Data correlated well with those by flame photometry for Na+ and K+ and with those by coulometry for Cl-, both for various biological materials--sera, urines, dialysis fluids--and commercial control materials from various producers. Stability of the potentiometric signal was acceptable: daily variations were 0.2 mV for Na+, 0.05 mV for K+, and 0.03 mV for Cl-. Accordingly, we conclude that the system supplies reproducible and accurate results while being easy to use and requiring little maintenance. The use of indirect potentiometry offers results consistent with those obtained with traditional methods, and easily interpretable by clinical staff. However, better information about the actual ion activity in the tested sample for certain pathologies such as hyperlipemia and dysproteinemia could be obtained by methods involving direct potentiometry.

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12

Aguirre-Londoño, Jessica, Víctor Alexander Aristizabal-Ferreira, Sandra Patricia Castro-Narváez e Juan Sebastián Ramírez-Navas. "Conductimetry: a rapid alternative technique for chlorides determination in cheese". Universitas Scientiarum 24, n. 2 (22 aprile 2019): 307–22. http://dx.doi.org/10.11144/javeriana.sc24-2.cara.

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The correlation of two instrumental techniques for chlorides determination in Colombian cheese, Queso Molido Nariñense (a type of white cheese), was analyzed. Potentiometry of chloride precipitation is the standard technique to determined salt in cheese. Conductimetry is an alternative technique. Samples of Queso Molido Nariñense were made. In the processed cheeses the salt concentration (NaCl: 0.5 %, 0.8 %, 1.0 %, 2.0 %, 3.0% and 6.0 %) was varied. Chlorides were determined by titration with silver nitrate in the potentiometric technique. In the conductimetric technique, each sample was analyzed by direct measuring its conductivity at room temperature. It was found that there is an adequate correlation between potentiometry and conductimetry. A maximum concentration of 2% NaCl in cheese is equivalent to 2.9 S/cm for conductivity readings. Additionally, it was verified that the conductimetry constitutes an analytically reliable technique for the determination of chlorides in cheese, it is friendlier to the environment, cheaper and faster.

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13

Bakker, Eric, e Ernö Pretsch. "Nanoscale potentiometry". TrAC Trends in Analytical Chemistry 27, n. 7 (luglio 2008): 612–18. http://dx.doi.org/10.1016/j.trac.2008.04.007.

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14

Bakker, Eric, e Ernö Pretsch. "Modern Potentiometry". Angewandte Chemie International Edition 46, n. 30 (23 luglio 2007): 5660–68. http://dx.doi.org/10.1002/anie.200605068.

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15

Isvoranu, Marian, Constantin Luca, Maria Pleniceanu e Cezar Spinu. "Studies on a Pb2+ - selective electrode with a macrocyclic liquid membrane: Potentiometric determination of pb2+ ions". Journal of the Serbian Chemical Society 71, n. 12 (2006): 1345–52. http://dx.doi.org/10.2298/jsc0612345i.

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This paper presents experimental and theoretical data regarding the design, characterization and analytical applications of a non-expensive, liquid-membrane ion-selective electrode for Pb2+ ions. The membrane is a solution of the active complex formed by Pb2+ ions with dibenzo-18-crown-6-ionophore (DB-[18]-C-6) extracted in propylene carbonate (PC). The successful application of the developed electrode for the determination of Pb2+ ions in aqueos solution samples by direct potentiometry and potentiometric titration is presented. For the presented analytical results, there are insignificant systematic errors between the direct potentiometric method with the developed ion-selective electrode and atomic absorption spectrometry. .

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16

Islam, Md Shafiul, e Maryanne M. Collinson. "Improved Sensitivity and Selectivity for the Redox Potentiometric Measurement of Biological Redox Molecules Using Nafion-Coated Platinum Decorated Nanoporous Gold Electrodes". Journal of The Electrochemical Society 169, n. 5 (1 maggio 2022): 057503. http://dx.doi.org/10.1149/1945-7111/ac68a1.

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Sensitivity and selectivity are two important figures of merit in analytical measurements, but in redox potentiometry, they are often limited. In this study, we describe how the potentiometric sensitivity and selectivity can be improved using nanoporous gold (NPG) electrodes with hydrogen peroxide, dopamine, ascorbic acid, and a mixture of dopamine and ascorbic acid as the test analytes. The results show that the addition of platinum (Pt) to the nanoporous framework significantly improves electrode sensitivity for the analytes studied. Furthermore, it was only possible to potentiometrically detect hydrogen peroxide at the NPG-Pt electrodes. To further improve sensitivity and also impart some selectivity, the electrodes were spin-coated with Nafion. The addition of Nafion shifts the open-circuit potential to more positive values, increases sensitivity by almost a factor of 2, and imparts selectivity to the surface for the analysis of mixtures. Collectively, this works shows the promise of Pt-decorated nanoporous electrodes coupled with a Nafion film to improve the overall performance of redox potentiometry in analytical science.

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17

Muralt, P., e D. W. Pohl. "Scanning tunneling potentiometry". Applied Physics Letters 48, n. 8 (24 febbraio 1986): 514–16. http://dx.doi.org/10.1063/1.96491.

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18

Manzo, Ruben H., e Ernestina Luna. "Differential scanning potentiometry". Analytical Chemistry 58, n. 6 (maggio 1986): 1055–57. http://dx.doi.org/10.1021/ac00297a016.

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19

Möller, R. "Scanning noise potentiometry". Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures 9, n. 2 (marzo 1991): 609. http://dx.doi.org/10.1116/1.585468.

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20

Jagner, Daniel, e Yudong Wang. "Coulometric stripping potentiometry". Electroanalysis 7, n. 7 (luglio 1995): 614–18. http://dx.doi.org/10.1002/elan.1140070703.

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21

Fernandes, J. C. B., e E. V. Heinke. "Alternative strategy for manufacturing of all-solid-state reference electrodes for potentiometry". Journal of Sensors and Sensor Systems 4, n. 1 (12 febbraio 2015): 53–61. http://dx.doi.org/10.5194/jsss-4-53-2015.

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Abstract. This paper presents an alternative strategy for manufacturing solid-state reference electrodes based on particles of graphite/silver/silver chloride synthesized by electroless deposition of metallic silver and silver chloride on graphite powder. Two kinds of reference electrodes were manufactured by mixing these particles with epoxy resin and hardener: quasi-reference and all-solid-state containing salts of alkaline or alkaline earth metals. All-solid-state reference electrodes can be sterilized with high-pressure saturated steam at 394.15 K (121 °C) using an autoclave. These electrodes presented a stable potential between pH 2 and 11. The electrode surface was characterized by scanning electron microscopy and showed the presence of silver and salt particles. The size of the silver particles was less than 2.5 μm. We successfully applied the all-solid state reference electrodes in potentiometric cells to measure pH and potassium ions in complex matrix by direct potentiometry and L-ascorbic acid by potentiometric titration.

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22

Yadav, Amar Prasad. "Preparation of Low Cost Solid State Silver Sulfide Based Bromide Selective Electrodes". Journal of Nepal Chemical Society 27 (22 agosto 2012): 100–106. http://dx.doi.org/10.3126/jncs.v27i1.6668.

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Preparation and performance of a cost effective silver sulfide based bromide selective membrane is described. A solid contact between membrane and body of the electrode was examined as an ion-selective electrode by determining S2- and Br- ions by direct potentiometry. A linear response to bromide ion from 2 x 10-5 to 10-1 M with a slope of 57.3 mV per decade [Br-] is observed. The membrane has a very short response. It gives excellent results as an indicator electrode for potentiometric titration.DOI: http://dx.doi.org/10.3126/jncs.v27i1.6668 J. Nepal Chem. Soc., Vol. 27, 2011 100-106

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23

Nakov, Natalija, Jelena Acevska, Katerina Brezovska e Aneta Dimitrovska. "Overview on chromatographic and potentiometric based approaches for pKa determination of sparingly soluble substances". Macedonian Pharmaceutical Bulletin 63, n. 02 (2018): 21–27. http://dx.doi.org/10.33320/maced.pharm.bull.2017.63.02.003.

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The dissociation constant (pKa) is one of the most important physicochemical property of the compounds and it is of great importance for the pharmaceutical industry. Many of the active pharmaceutical ingredients are sparingly soluble in water or have no chromophore, thus the conventional UV/Vis spectrometry and potentiometry methods are not applicable. This article presents an overview of several approaches based on RP-HPLC and cosolvent/surfactant potentiometry that have been recently published for the pKa determination of sparingly soluble active pharmaceutical ingredients. Additionally, different calculation methods that have been used for the estimation of the aqueous dissociation constant are summarized. Keywords: dissociation constant, pKa, sparingly soluble substances, determination, reverse-phase liquid chromatography, potentiometry, surfactants

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Jobst, Johannes, Jaap Kautz, Maria Mytiliniou, Rudolf M. Tromp e Sense Jan van der Molen. "Low-energy electron potentiometry". Ultramicroscopy 181 (ottobre 2017): 74–80. http://dx.doi.org/10.1016/j.ultramic.2017.05.015.

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Bakker, Eric, e Ernö Pretsch. "Potentiometry at trace levels". TrAC Trends in Analytical Chemistry 20, n. 1 (gennaio 2001): 11–19. http://dx.doi.org/10.1016/s0167-2940(01)90073-1.

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26

Düzgün, Ali, Gustavo A. Zelada-Guillén, Gastón A. Crespo, Santiago Macho, Jordi Riu e F. Xavier Rius. "Nanostructured materials in potentiometry". Analytical and Bioanalytical Chemistry 399, n. 1 (14 luglio 2010): 171–81. http://dx.doi.org/10.1007/s00216-010-3974-3.

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27

Hongguang, Zhang, e Jin Wenrui. "Investigations of adsorption potentiometry". Journal of Electroanalytical Chemistry 356, n. 1-2 (settembre 1993): 171–79. http://dx.doi.org/10.1016/0022-0728(93)80519-n.

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28

Rizov, Ivelin, e Liliana Ilcheva. "Differential flow injection potentiometry". Analytica Chimica Acta 311, n. 2 (luglio 1995): 175–81. http://dx.doi.org/10.1016/0003-2670(95)00187-5.

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Jin, Wenrui, e Junying Wang. "Investigations on adsorption potentiometry". Journal of Electroanalytical Chemistry and Interfacial Electrochemistry 306, n. 1-2 (maggio 1991): 31–40. http://dx.doi.org/10.1016/0022-0728(91)85220-j.

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YANG, SUSIE XIURU, K. L. CHENG, L. T. KURTZ e T. R. PECK. "SUSPENSION EFFECT IN POTENTIOMETRY". Particulate Science and Technology 7, n. 3 (gennaio 1989): 139–52. http://dx.doi.org/10.1080/02726358908906533.

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Yamasue, Kohei, e Yasuo Cho. "Scanning nonlinear dielectric potentiometry". Review of Scientific Instruments 86, n. 9 (settembre 2015): 093704. http://dx.doi.org/10.1063/1.4930181.

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Jin, Wenrui, Yanhong Zheng e Xia Qu. "Investigations on adsorption potentiometry". Analytica Chimica Acta 262, n. 1 (giugno 1992): 123–27. http://dx.doi.org/10.1016/0003-2670(92)80016-z.

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Jin, Wenrui, Li Xiao e Yan Wu. "Investigations on adsorption potentiometry". Analytica Chimica Acta 280, n. 1 (agosto 1993): 69–74. http://dx.doi.org/10.1016/0003-2670(93)80243-e.

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Mulyasuryani, Ani, Anna Roosdiana e Arie Srihardyastutie. "THE POTENTIOMETRIC UREA BIOSENSOR USING CHITOSAN MEMBRANE". Indonesian Journal of Chemistry 10, n. 2 (21 luglio 2010): 162–66. http://dx.doi.org/10.22146/ijc.21454.

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Potentiometric urea biosensor development is based on urea hydrolysis by urease resulted CO2. The biosensor is used chitosan membrane and the H3O+ electrode as a transducer. The research was studied of effecting pH and membrane thickness to the biosensor performance. The best biosensor performance resulted at pH = 7.3 and 0.2 mm of membrane thickness. The biosensor has a Nerntian factor 28.47 mV/decade; the concentration range is 0.1 up to 6.00 ppm; and the limit of detection is 0.073 ppm. The response time of this biosensor is 280 seconds, efficiency 32 samples and accuracy 94% up to 99%. Keywords: biosensor, potentiometry, urea, chitosan membrane

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Hitchman, Michael L., e Frazier W. M. Nyasulu. "Potentiometric monitoring of proteins. Part 3.—Direct potentiometry with a copper electrode". Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 82, n. 4 (1986): 1223. http://dx.doi.org/10.1039/f19868201223.

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Foti, Claudia, e Ottavia Giuffrè. "Interaction of Ampicillin and Amoxicillin with Mn2+: A Speciation Study in Aqueous Solution". Molecules 25, n. 14 (8 luglio 2020): 3110. http://dx.doi.org/10.3390/molecules25143110.

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A potentiometric and UV spectrophotometric investigation on Mn2+-ampicillin and Mn2+-amoxicillin systems in NaCl aqueous solution is reported. The potentiometric measurements were carried out under different conditions of temperature (15 ≤ t/°C ≤ 37). The obtained speciation pattern includes two species for both the investigated systems. More in detail, for system containing ampicillin MLH and ML species, for that containing amoxicillin, MLH2 and MLH ones. The spectrophotometric findings have fully confirmed the results obtained by potentiometry for both the systems, in terms of speciation models as well as the stability constants of the formed species. Enthalpy change values were calculated via the dependence of formation constants of the species on temperature. The sequestering ability of ampicillin and amoxicillin towards Mn2+ was also evaluated under different conditions of pH and temperature via pL0.5 empirical parameter (i.e., cologarithm of the ligand concentration required to sequester 50% of the metal ion present in traces).

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Yao, Yao, Yibin Ying e Jianfeng Ping. "Development of a Graphene Paper-Based Flexible Solid-Contact Lead Ion-Selective Electrode and its Application in Water". Transactions of the ASABE 62, n. 2 (2019): 245–52. http://dx.doi.org/10.13031/trans.12906.

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Abstract. A graphene paper-based flexible solid-contact ion-selective electrode (SC-ISE) was developed to detect lead ion sensitively. Graphene paper obtained via a simple vacuum filtration method was used as the electrode substrate for direct coating of an ion-selective membrane. The Nernstian slope of the prepared paper-based potentiometric sensor toward lead ion detection was demonstrated as 29.4 mV per decade. A detection limit as low as 2.5 × 10-7 mol L-1 was achieved. Reversed chronopotentiometry and water layer test revealed that the graphene paper-based SC-ISE possessed excellent potential stability because of the hydrophobicity of graphene paper. Furthermore, reliable data were obtained from the detection of lead ion levels in real water samples using the graphene paper-based potentiometric sensor, which shows great potential in practical application. Keywords: Graphene paper, Heavy metal, Ion-selective electrode, Potentiometry, Water sample.

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Suljkanović, Mersiha, Malgorzata Grabarczyk, Cecylia Wardak, Marzena Adamczyk e Karolina Pietrzak. "Electrochemical sensors as simple and cheap devices for rapid determination of various species in environmental samples". Environmental engineering 6, n. 1 (16 luglio 2019): 1–6. http://dx.doi.org/10.37023/ee.6.1.1.

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The electrochemical methods are very good tool for determination of trace concentrations of various species in water samples. The analysis carried out using these methods are usually simple, fast and also the cost of the required equipment is much lower comparing to other instrumental methods. Furthermore, the electroanalytical methods are easy to automate and computerize. Among five major groups of these methods (potentiometry, voltammetry, coulometry, conductometry and dielectrometry), potentiometry and voltammetry attract the greatest attention of researchers. In this paper, experimental results of research related to development of procedures (voltammetric and potentiometric) for the determination of elements in environmental water samples were presented. Due to their common occurrence in environment and possible toxic effects on living organisms, vanadium and nitrate ions were selected for investigation. Optimization of voltammetric procedure for V(V) determination were carried out in matrix containing different surfactants and humic acids, using lead film electrode as a working electrode. Results showed that only nonionic surfactant Brij-35 did not interfere with the voltammetric signal. Other surfactants as well as humic acids reduced the signal, and possibility of their elimination with suitable resins were also investigated. Potentiometric measurements were consisted of preparation and determination of analytical properties of nitrate ion-selective electrodes with solid contact. The results showed that among three different membrane composition, the best response was achieved by membrane containing: Ni(Phen)2, THTDPCl, PVC and NPOE in the ratio of 1:2:33:64 wt. %, respectively. With the detection limit of 2.8 × 10-6 mol L-1, the working concentration range from 5 × 10-5 to 1 × 10-1 mol L-1 and a slope of -55.1 mV per decade, this electrode showed good selectivity to sulfate, acetate, carbonate, dihydrogen phosphate, fluoride and chloride ions, and also good potential reversibility.

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Bakker, Eric. "A Scientific Journey with Ionophore-based Sensors". CHIMIA International Journal for Chemistry 74, n. 7 (12 agosto 2020): 569–76. http://dx.doi.org/10.2533/chimia.2020.569.

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This article describes selected historical milestones in the field of neutral ionophore-based sensors, starting with the first discovery by Wilhelm Simon and their impact to analytical sciences despite the initial difficulty to understand their function. The reader is then guided through topics in which the author has been involved over the years, from understanding thermodynamic aspects to the field of non-equilibrium potentiometry, polyion sensors, trace level potentiometry, instrumentally controlled ion sensors and finally potentiometry involving local perturbations and transient currents that allow for new readout possibilities. Discussed applications include clinical diagnostics, environmental in situ sensing/profiling and speciation analysis. The article loosely follows the content of the Simon-Widmer Award lecture of the same title presented by the author at the CH Analysis 2019 conference in Beatenberg, Switzerland.

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40

Kholifa, Mulik, Tri Mulyono e Yeni Maulidah Muflihah. "Simultaneous Determination of Magnesium (Mg2+) and Ammonium (NH4+) by Flow Injection Analysis". Jurnal ILMU DASAR 19, n. 1 (28 febbraio 2018): 1. http://dx.doi.org/10.19184/jid.v19i1.5483.

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Abstract (sommario):

An automatic method for the simultaneous determination of magnesium and ammoniun by flow injection analysis is described. This analysis used two detectors, potentiometry and spectrophotometry, for the determination of magnesium and ammonium simultaneously. Potentiometric detectors are used to detect ammonium ions, whereas spectrophotometer detectors are used to detect the presence of magnesium ions. The performance of the FIA system includes linear range linearity, limit of detection, sensitivity, reproducibility and recovery test. Spectrophotometry FIA showed good performance with several criteria of linearity with regression value of 0.9918, the detection limit of 0.06 ppm, a sensitivity of 0.0115, repeatability of less than 2% and the percent recovery of 91,6%. While potentiometric FIA showed th performance with several criteria of linearity with regression value of 0.9896, the detection limit of 0.17 ppm, a sensitivity of 40.747 mV per decade of concentration, repeatability of less than 2% and the percent recovery of 89,7%. Keywords: Flow Injection Analysis, spectrophotometry, potensiometry, simultaneous

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41

Hassan, Saad S. M., e Mona A. Ahmed. "Polyvinyl Chloride Matrix Membrane Electrodes for Manual and Flow Injection Analysis of Chloroquine in Pharmaceutical Preparations". Journal of AOAC INTERNATIONAL 74, n. 6 (1 novembre 1991): 900–905. http://dx.doi.org/10.1093/jaoac/74.6.900.

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Abstract Two types of polyvinyl chloride (PVC) matrix membrane electrodes responsive to the antimalarial drug chloroquine have been constructed, electrochemically evaluated, compared, and used in pharmaceutical analysis. Type 1 is the classic PVC model with chloroquine-tetraphenylborate (TPB) sensor; Type 2 is a coated silver disk without internal filling solution. Both electrode types exhibited rapid linear potentiometric response to the logarithmic concentration of diprotonated chloroquine cation in the 10−1–10−6M range with calibration slopes 28-30 mV/concentration decade over the pH range 1.8-6.2. These electrodes were sensitive enough to permit determination of chloroquine phosphate at concentrations as low as 5 μg/mL with good accuracy and precision. Determination of chloroquine in various pharmaceutical preparations using direct potentiometry and potentiometric titration with NaTPB gave an average recovery of 98.8% of the nominal values (SD 0.5%). The Type 2 electrode was also assessed in a flow-through sandwich cell for flow injection analysis. Results were compared with data obtained by the U.S. Pharmacopeia method.

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42

Boeyckens, Ann, Jan Schots, Hugo Vandenplas, Freedy Senesael, Wim Goedhuys e Frans K. Gorus. "Ektachem Slides for Direct Potentiometric Determination of Sodium in Plasma: Effect of Natremia, Blood pH, and Type of Electrolyte Reference Fluid on Concordance with Flame Photometry and Other Potentiometric Methods". Clinical Chemistry 38, n. 1 (1 gennaio 1992): 114–18. http://dx.doi.org/10.1093/clinchem/38.1.114.

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Abstract With electrolyte reference fluid (ERF)00, results from Kodak Ektachem slides for the direct potentiometric assay of sodium in plasma were significantly correlated with results from flame photometry, but also appeared to be systematically higher, especially in hypernatremic patients. Indirect potentiometry with the Technicon RA-1000 yielded intermediate values. In 23 hypernatremic patients with greater than or equal to 6 mmol/L difference in sodium between Ektachem ERF00 and flame photometry, a clinical survey disclosed the frequent association of large between-method differences with renal failure, diabetes mellitus, and gastrointestinal disease. However, there was no correlation between differences in sodium on the one hand and anion gaps or (lipo)protein concentrations on the other, nor did in vitro addition studies implicate metabolites that often accumulate in the above-mentioned disorders. Unlike indirect methods, sodium measurements by direct potentiometry on Ektachem and Corning were influenced by in vitro changes of pH between 7.0 and 7.9. However, in a group of patients that included many acidotic individuals, between-method differences in sodium appeared not significantly correlated with in vivo blood pH. Use of the equitransferant ERF04 on Ektachem strongly diminishes the systematic differences with flame photometry, reduces the pH-dependency of the results to that of the direct Corning method, and brings the mean analytical recovery of sodium to below 95% (instead of 115% previously) without affecting the ability of Ektachem slides to avoid spuriously low results in the presence of increased (monoclonal) protein concentrations.

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43

Takahashi, Akio, Takayuki Natsume, Nobuyoshi Koshino, Shigenobu Funahashi, Yasuhiro Inada e Hideo D. Takagi. "Speciation of trimethyltin(IV): hydrolysis, complexation equilibria, and structures of trimethyltin(IV) ion in aqueous solution". Canadian Journal of Chemistry 75, n. 8 (1 agosto 1997): 1084–92. http://dx.doi.org/10.1139/v97-128.

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The hydrolysis constants of trimethyl- and triethyltin(IV) ions and the stability constants for the complexation of trimethyltin(IV) with trimethylamine, N-substituted glycines (N,N-dimethylglycine and N,N,N-trimethylglycine), and aminopolycarboxylate ions (N-methyliminodiacetate, nitrilotriacetate, and ethylenediamine-N,N′-diacetate) were determined by the potentiometric method at 25 °C and I = 0.l mol dm−3 ((H, Na)ClO4 and (H, Na)NO3). The structural parameters of Me3Sn(OH2)2, Et3Sn(OH2)2, and Me3Sn(OH2)(OH) in solution were determined by the EXAFS method. The coordination structures of trimethyltin(IV) complexes with N-substituted glycines, trimethylamine, and aminopolycarboxylate ions are discussed on the basis of the electronic interaction between the donor atom and Sn(IV). Keywords: organotin(IV), EXAFS, structure, potentiometry.

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44

Ma, Ming Ming, Zhi Tong e Yong Wen. "Poly Silk Peptide Film PH Sensor Based on Zero Current Potentiometry". Advanced Materials Research 450-451 (gennaio 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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45

Jornet-García, Alfonso, Arturo Sanchez-Perez, José María Montoya-Carralero e María José Moya-Villaescusa. "Electrical Potentiometry with Intraoral Applications". Materials 15, n. 15 (22 luglio 2022): 5100. http://dx.doi.org/10.3390/ma15155100.

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Dental implants currently in use are mainly made of titanium or titanium alloys. As these metallic elements are immersed in an electrolytic medium, galvanic currents are produced between them or with other metals present in the mouth. These bimetallic currents have three potentially harmful effects on the patient: micro-discharges, corrosion, and finally, the dispersion of metal ions or their oxides, all of which have been extensively demonstrated in vitro. In this original work, a system for measuring the potentials generated in vivo is developed. Specifically, it is an electrogalvanic measurements system coupled with a periodontal probe that allows measurement of the potentials in the peri-implant sulcus. This device was tested and verified in vitro to guarantee its applicability in vivo. As a conclusion, this system is able to detect galvanic currents in vitro and it can be considered capable of being employed in vivo, so to assess the effects they may cause on dental implants.

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46

Reymond, S., e O/ Fischer. "Low temperature scanning contact potentiometry". Review of Scientific Instruments 75, n. 3 (marzo 2004): 694–98. http://dx.doi.org/10.1063/1.1646742.

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47

Janata, J. "Nernstian and non-nernstian potentiometry". Solid State Ionics 94, n. 1-4 (1 febbraio 1997): 209–15. http://dx.doi.org/10.1016/s0167-2738(96)00503-6.

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48

Noyhouzer, T., I. Valdinger e D. Mandler. "Enhanced Potentiometry by Metallic Nanoparticles". Analytical Chemistry 85, n. 17 (15 agosto 2013): 8347–53. http://dx.doi.org/10.1021/ac401744w.

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49

Cheng, K. L. "Capacitor theory for nonfaradaic potentiometry". Microchemical Journal 42, n. 1 (agosto 1990): 5–24. http://dx.doi.org/10.1016/0026-265x(90)90023-x.

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50

Kolev, Spas D., Christopher W. K. Chow, David E. Davey e Dennis E. Mulcahy. "Oscillating flow injection stripping potentiometry". Analytica Chimica Acta 309, n. 1-3 (giugno 1995): 293–99. http://dx.doi.org/10.1016/0003-2670(95)00091-d.

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