Temat: potentiometry - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Potentiometric determination of cysteine with thiol sensitive silver-mercury electrode
Autorzy:: Naskalski, Jerzy
Drożdż, Ryszard
Ząbek-Adamska, Anna
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 2.

Tytuł:: Potentiometric determination of cysteine with thiol sensitive silver-mercury electrode
Autorzy:: Drożdż, Ryszard
Naskalski, Jerzy
Ząbek-Adamska, Anna
Tematy:: potentiometry
cysteine
real time assay
homocysteine
glutathione; Pokaż więcej
Wydawca:: Polskie Towarzystwo Biochemiczne
Powiązania:: https://bibliotekanauki.pl/articles/1041141.pdf Link otwiera się w nowym oknie
Opis:: A potentiometric procedure for cysteine thiol group concentration monitoring in media generating free radicals was developed using a thiol specific silver-mercury electrode. Electrolytic deposition of mercury on a silver wire and treatment with 20 mM cysteine in 0.5 M NaOH were used to produce the electrode. A silver-chloride electrode in saturated KCl was the reference. A glass capillary with 1 M KNO3 in 1% agarose gel was the liquid junction. The electrode responded to cysteine concentration in the range from 0.01 to 20 mM yielding a perfect linear relationship for the dependence of log [cysteine] versus electrode potential [mV], with b0 (constant) = -373.43 [mV], b1 (slope) = -53.82 and correlation coefficient r2 = 0.97. The electrode potential change per decade of cysteine concentration was 57 mV. The minimal measurable signal response was at a cysteine concentration of 0.01 mM. The signal CV amounted to 4-6% for cysteine concentrations of 0.01 to 0.05 mM and to less than 1% for cysteine concentrations of 0.5 to 20 mM. The response time ranged from about 100 s for cysteine concentrations of 0.01 to 0.1 mM to 30 s at higher cysteine concentrations. The standard curve reproducibility was the best at cysteine concentrations from 0.1 to 20 mM. In a reaction medium containing cysteine and copper(II)-histidine complex ([His-Cu]2+) solution in 55 mM phosphate buffer pH 7.4 the electrode adequately responded to changes in cysteine concentration. Beside cysteine, the silver-mercury electrode responded also to thiol groups of homocysteine and glutathione, however, the Nernst equation slope was about half of that for cysteine.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Characteristics of carbon nanomaterials and their application in the construction of potentiometric sensors – review
Autorzy:: Pietrzak, Karolina
Wardak, Cecylia
Tematy:: potentiometry
ion-selective electrodes
potentiometric sensors
nanoparticles
carbon nanomaterials; Pokaż więcej
Wydawca:: Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Powiązania:: https://bibliotekanauki.pl/articles/2079906.pdf Link otwiera się w nowym oknie
Opis:: Carbon nanomaterials have been very popular in the scientific community in recent years, because of their unusual physical and chemical properties. Their high electrocatalytic activity, very good electrical conductivity and mechanical resistance mean that scientists are constantly looking for new technological solutions to take advantage of the opportunities offered by nanomaterials in many areas of human activity. One of such area are potentiometric sensors. There are many publications in which scientists describe methods of construction, analytical parameters and practical applications of new sensors obtained using carbon nanomaterials, and often also describe methods of synthesis of new original nanomaterials. The purpose of this work was to characterize carbon-based nanomaterials and their application in the construction of ion-selective electrodes.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Some micro- and trace elements in selected bottled natural waters from the Polish market evaluated by electrochemical methods
Autorzy:: Opoka, W.
Szlósarczyk, M.
Maślanka, A.
Rojowski, J.
Stopa, K.
Borkowska, I.
Muszyńska, B.
Tyszka-Czochara, M.
Tematy:: natural waters
stripping voltammetry
potentiometry
trace elements
microelements; Pokaż więcej
Wydawca:: Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Powiązania:: https://bibliotekanauki.pl/articles/1190181.pdf Link otwiera się w nowym oknie
Opis:: Although beneficial properties of mineral waters are acknowledged by law in many countries, the use of water for medicinal purposes is not universally accepted. Notably numerous waters (especially mineral and curative ones) have high concentrations of mineral and trace elements. These mineral waters are common on the market and their availability is not regulated by law. Due to the hazard of overdosing, quantification of trace elements and minerals seems to be necessary. The World Health Organization, European Standards and Polish Standards recommend different methods for elemental determination, i.e. spectrometry, photometry for zinc determination, colorimetry or spectrometry for copper, and ionic chromatography for calcium, chloride and fluoride. In this paper, alternative, electrochemical methods have been applied to determine zinc, copper, calcium, chloride and fluoride in most popular natural and curative waters from southern Poland. The determined elemental content varied between 3.85-33.54 μg L-1 for zinc, 85-15.33 μg L-1 for copper, 2.8-2433.63 mg L-1 for chloride, 0.4-1.66 mg L-1 for fluoride and 11.05-478.48 mg L-1 for calcium. The voltammetric method was tested according to the validation procedures, taking into account the following parametes: linearity range, limit of detection and limit of quantification and precision. The results show that the applied electroanalytical methods are suitable for determination of the selected elements in waters of natural origin, ensuring low instrumental and analysis costs while providing results comparable with ones achieved with recommended methods.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Potentiometric detection of the metabolic activity of human tumor cells
Autorzy:: Kwapiszewska, K.
Stępień, K.
Sendys, P.
Chudy, M.
Brzózka, Z.
Tematy:: cancer
in vitro cell culture
potentiometry
cell culture monitoring; Pokaż więcej
Wydawca:: Fundacja na Rzecz Młodych Naukowców
Powiązania:: https://bibliotekanauki.pl/articles/115519.pdf Link otwiera się w nowym oknie
Opis:: Monitoring of cellular viability is a key part of toxicological assays in vitro. On-line monitoring of metabolic activity would be particularly useful for evaluation of responses to potential therapeutic compounds. Current assays are mostly based on fluorescent dyes and optical detection methods. These methods offer high sensitivity and specificity, however are not suitable for long-term on-line observations. Electrochemical methods can be an alternative for current protocols. Electrochemical detection is low cost and label-free, therefore suitable for long-term cell culture monitoring. In this work investigations on human cancer cells viability will be presented. Cells were cultured as two-dimensional monolayer or three-dimensional spheroids. Different cell culture media were examined. Potentiometric detection was used for continuous monitoring of cell culture as well as end-point investigations. Different growth phases were identified using applied method. Finally, response to an anticancer drug was successfully observed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Single-piece all-solid-state Co(II) ion-selective electrode for cobalt monitoring in real samples
Autorzy:: Wardak, C.
Grabarczyk, M.
Tematy:: cobalt(II) ion-selective electrode
ionic liquids
solid contact
potentiometry; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Agrofizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2082867.pdf Link otwiera się w nowym oknie
Opis:: A novel single-piece all-solid-state ion-selective electrode for Co2+ determination has been prepared. The PVC membrane was modified by the addition of ionic liquid. The effect of various ionic liquids was studied in detail and improved performance was observed. The best performance exhibited by the electrode was achieved with a membrane containing 1-ethyl- 3-methyl imidazolium chloride, having a slope of 31.8 mV/ decade in a wide concentration range of 1×10-7 – 1×x10-1 mol L-1. The limit of detection was 5.6×10-8 mol L-1. The response time of the proposed sensor was less than 10 s and the lifetime was at least three months. The proposed sensor showed good selectivity towards the Co2+ ion in comparison with some alkali, alkaline earth, transition and heavy metal ions. It was successfully applied for the direct determination of cobalt ions in real sample solution.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Effect of structure and properties of membrane active substance on analytical performance of ion-selective electrodes
Autorzy:: Wardak, Cecylia
Grabarczyk, Małgorzata
Lenik, Joanna
Tematy:: ion-selective electrode
acidic chelating ionophore
PVC membrane
potentiometry
spectrophotometry; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/110902.pdf Link otwiera się w nowym oknie
Opis:: The potential creating properties of a group of acidic chelating compounds are presented. The studies have been carried out by the constructing of new ion-selective electrodes based on PVC membranes doped with the studied compounds, and determining the basic analytical parameters of the electrodes. The usefulness of eight out of nine investigated compounds in the preparation of the membrane phase electrodes selective for cobalt, zinc and cadmium has been shown. It has been also found that the acidic properties of ionophore have an essential influence on the analytical parameters of the constructed electrodes. The response mechanism of the obtained electrodes has been investigated by simultaneous spectrophotometric-potentiometric measurement of membranes used in electrodes. It has been found that during the conditioning of electrode, a complex of active substance with primary ion is formed in the membrane phase, then the membrane composition is established and remains unchanged in the next measurements.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Probing the electronic transport on the reconstructed Au/Ge(001) surface
Autorzy:: Wojtaszek, Mateusz
Kaspers, Mark R.
Jany, Benedykt
Bernhart, Alexander M.
Möller, Rolf
Krok, Franciszek
Nikiel, Marek
Indyka, Paulina
Bobisch, Christian A.
Opis:: By using scanning tunnelling potentiometry we characterized the lateral variation of the electrochemical potential $\mu _{ec}$ on the gold-induced Ge(001)-c(8 × 2)-Au surface reconstruction while a lateral current flows through the sample. On the reconstruction and across domain boundaries we find that $\mu _{ec}$ shows a constant gradient as a function of the position between the contacts. In addition, nanoscale Au clusters on the surface do not show an electronic coupling to the gold-induced surface reconstruction. In combination with high resolution scanning electron microscopy and transmission electron microscopy, we conclude that an additional transport channel buried about 2 nm underneath the surface represents a major transport channel for electrons.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 9.

Tytuł:: Analysis of the Fibroin Solution State in Calcium Chloride/Water/Ethanol for Improved Understanding of the Regeneration Process
Analiza stanu roztworu fibroiny w chlorku wapnia/wodzie/etanolu w celu lepszego zrozumienia procesu regeneracji
Autorzy:: Ngo, H.-T.
Bechtold, T.
Tematy:: fibroin
calcium chloride
potentiometry
complex formation
regeneration
dissolution
chlorek wapnia
potencjometria
kompleksowanie
regeneracja
rozpuszczanie; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Powiązania:: https://bibliotekanauki.pl/articles/232222.pdf Link otwiera się w nowym oknie
Opis:: Shaping of fibroin protein from Bombyx mori from calcium chloride/water/ethanol solution is of high interest for the manufacturing of biocompatible structures. Potentiometric titration experiments of the dissolved state permit new insight into the solution state of fibroin as a basis for improved regeneration. Titration experiments and infrared spectroscopy of the solution state support the model of an ion-rich hydration layer and interaction of the solvent with charged and polar groups of the fibroin, rather than through formation of defined calcium complexes. The potentiometric titration curves indicate the formation of calcium complexes at pH values above 9, most probably through involvement of basic amino acids and phenolic groups of tyrosine. After regeneration by the addition of methanol, the regenerated protein was characterised by FTIR, nitrogen and calcium analysis. The analysis of supernatants for their residual protein content indicated minor losses of protein, most probably low molecular weight proteins. The results contribute to an improved understanding of the solution state as a basis for larger scale regeneration, e.g. for the coating of textile fibres with regenerated fibroin.
Fibroiny z Bombyx mori z roztworu chlorku wapnia/wody/etanolu są bardzo interesujące z punktu widzenia wytwarzania biokompatybilnych struktur. Eksperymenty potencjometryczne z miareczkowaniem pozwalają na nowy wgląd w roztwór fibroiny jako podstawy do lepszej regeneracji. Miareczkowanie i spektroskopia w podczerwieni roztworu wspierają model bogatej w jony warstwy hydratacyjnej i oddziaływanie rozpuszczalnika z naładowanymi i polarnymi grupami fibroiny. Potencjometryczne krzywe miareczkowania wskazują na tworzenie się kompleksów wapnia przy wartościach pH powyżej 9, najprawdopodobniej poprzez zaangażowanie podstawowych aminokwasów i grup fenolowych tyrozyny. Po regeneracji przez dodanie metanolu, zregenerowane białko scharakteryzowano za pomocą analizy FTIR, azotu i wapnia. Analiza pod kątem zawartości białka resztkowego wykazała niewielkie straty białka, najprawdopodobniej tego o niskiej masie cząsteczkowej. Wyniki przyczyniły się do lepszego poznania roztworu jako podstawy do regeneracji na większą skalę, np. do powlekania włókien tekstylnych regenerowaną fibroiną.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Towards automation of measurement processes of surface water parameters by a remote-controlled catamaran
Autorzy:: Wiora, A.
Kozyra, A.
Wiora, J.
Tematy:: measurement automation
remote controlled boat
environmental water analysis
potentiometry
automatyka pomiarowa
zdalnie sterowana łódź
analiza środowiska wodnego
potencjometria; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/201946.pdf Link otwiera się w nowym oknie
Opis:: This paper describes a way of determining selected water parameters using a prototype of a remote-controlled catamaran. The remote controlling allows to steer the boat and to manage the measurement process from the shore. It is possible to monitor the water parameters online as well as to store them and analyze them afterwards. The measured parameters are determined mainly using potentiometric methods and include several ion concentrations. The system is orientated towards monitoring breeding ponds or other similar surface waters. The mechanical construction of the catamaran, its electronic circuits and implemented software are described in detail in the paper. Conclusions obtained from preliminary tests are also included. The described construction allows analysts to perform simple and inexpensive remote measurements or assessments of water quality and reduces the time of such analysis in comparison to traditional sampling.
Dostawca treści:: Biblioteka Nauki

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