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Wyświetlanie 1-3 z 3
Tytuł:
Jonoselektywne sensory potencjometryczne i optyczne : podobne materiały konstrukcyjne, różne możliwości analityczne
Ion-sective potentiometric and optical sensors : similar construction materials, different analytical possibilities
Autorzy:
Michalska, A.
Maksymiuk, K.
Powiązania:
https://bibliotekanauki.pl/articles/172786.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
elektrody jonoselektywne
oktody
czujnik fluorymetryczny
nanosensory
ion-selective electrodes
optode
fluorimetric sensors
nanosensors
Opis:
Ion-selective electrodes are a routine tool of chemical analysis, characterized by beneficial analytical parameters, simple operation principle and low apparatus cost. In this group of sensors particularly advantageous are those with plastified poly- (vinyl chloride) based membranes, containing ionophore – interacting selectively with some cations [1]. From the practical point of view all-solid-state constructions became very useful. However, in this case, a solid contact should be added between the substrate electrode and the membrane, enabling reversible charge transfer on the electrode / solid contact and solid contact / membrane interfaces. On the other hand, an advantageous alternative for membrane material, instead of poly(vinyl chloride), are polyacrylates which can be easily obtained by photopolymerization and provide lower detection limits due to lower ion mobility in the membrane. Membranes of similar composition (containing ionophore) can be also applied in ion-selective optodes, where a solid contact is not needed, but additional membrane component is a dye (chromoionophore) of different colours of the protonated and deprotonated forms. Such optodes can be also obtained as microspheres, thus they can be introduced into a medium of low volume, e.g. living cells. The next step towards sensitivity increase and miniaturization is recording fluorescence intensity instead of absorbance, by using appropriate fluorophores, e.g. pyrene, and production of nanosensors, e.g. as micelles obtained from cross-linked alternative polymers. Appropriate modification of the surface phase of such nanosensors, affecting the permeability of analyte ions into the nanospheres, enables tailoring of the shape of analytical characteristics – from sigmoidal (high sensitivity, narrow linear response range) to linear dependence of the signal on logarithm of analyte concentration (low sensitivity, but wide linear response range).
Źródło:
Wiadomości Chemiczne; 2015, 69, 9-10; 687-699
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie elektrochemicznej absorpcji wodoru w palladzie i jego stopach przy użyciu elektrod o ograniczonej objętości
Study on electrochemical absorption of hydrogen in palladium and its alloys using limited volume electrodes
Autorzy:
Łukaszewski, M.
Grdeń, M.
Powiązania:
https://bibliotekanauki.pl/articles/172630.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
pallad
absorpcja wodoru
elektrody o ograniczonej objętości
stopy
palladium
hydrogen absorption
limited volume electrodes
alloys
Opis:
The review summarizes the results of the electrochemical studies on hydrogen absorption in Pd and Pd alloys prepared in the form of thin deposits on a hydrogen -neutral matrix. This kind of electrodes, called Limited Volume Electrodes (LVE), enables to limit and control the amount of absorbed hydrogen inside a Pd sample and makes it possible to study the process of hydrogen absorption under electrochemical conditions. The amount of absorbed hydrogen, phase transition potentials, hysteresis effect and the rate of hydrogen absorption/desorption can be determined using cyclic voltammetric, chronoamperometric and chronopotentiometric techniques. The mechanism of the interactions of hydrogen with Pd-LVE is presented. The influence of electrode potential, temperature and Pd layer thickness on the process of hydrogen absorption is discussed. The behavior of Pd alloys towards hydrogen is summarized. The interrelation between hydrogen absorption and surface processes is described. The examples of the use of LVE in applied electrochemistry are given.
Źródło:
Wiadomości Chemiczne; 2016, 70, 3-4; 219-252
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Współczesne podejścia elektrochemiczne do oznaczania arsenu
Recent approaches to electrochemical determination of arsenic
Autorzy:
Ozimek, W.
Rutkowska, I. A.
Cox, J. A.
Kulesza, P. J.
Powiązania:
https://bibliotekanauki.pl/articles/172485.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
arsen
oznaczenia elektrochemiczne
woltamperometria strippingowa
elektrokataliza
elektrody modyfikowane
nanocząstki metali
nanocząstki tlenków metali
arsenic
electrochemical determinations
stripping voltammetry
electrocatalysis
modified electrodes
metal nanoparticles
metal oxide nanoparticles
Opis:
There has been growing interest in development of new methods for the determination of arsenic due to its high toxity and increasing population in the environment. At present, chromatographic (separation) and spectroscopic (detection) approaches are the most common. Although, they are characterized by high sensitivity and low detection limits, the experimental procedures often require generation of toxic AsH3. Electrochemical methods for the determination of arsenic can be considered as complimentary because they are fairly simple and they are subject to different selectivity criteria. In this respect, various stripping voltammetric procedures are becoming popular. The actual stripping voltammetric measurement consists of two steps in which preconcentration of an analyte at the electrode surface is followed by the so called „stripping” step involving electrode reaction recorded in a form of the voltammetric peak. A representative approach involves reduction of the analyte anions upon application of the sufficiently negative potential to form As(0) on the electrode (e.g. gold) surface; this step is followed by voltammetric oxidation (anodic stripping) of the deposit (to As(III)). In a case of so called cathodic stripping voltammetry, the stationary Hanging Mercury Drop Electrode (HMDE) is often used. During the preconcentration step, an insoluble salt is produced on the electrode surface. To facilitate its formation, copper or selenium species are used as mediators. Under such conditions, insoluble Cu3As2 is generated together with copper amalgam on the surface of HMDE. Because sensitivity and detection limit in electroanalytical determinations strongly depend on the current densities measured, there is a need to search for specific catalytic materials that would induce otherwise highly slow and irreversible redox processes of As(III) (oxidation) and, in particular, As(V) (reduction). Designing effective electrocatalytic materials would be of importance to the development of more sensitive stripping methods and monitoring of arsenic under chromatographic and flow conditions. Representative examples of catalytic systems are provided and discussed here. Some attention is also paid to application of enzymes to sensing of arsenic. Electrochemical determination of arsenic(III) is generally better described in literature. Direct determination of As(V) typically requires its binding into chemical compounds. It is reasonable to expect intense research in future aiming at the developing of new electroanalytical methods for direct selective determination of As(V).
Źródło:
Wiadomości Chemiczne; 2015, 69, 9-10; 809-822
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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