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Ion Selective Electrode (ion + selective_electrode)

Distribution by Scientific Domains

Medical Sciences	25%

Selected Abstracts

Solid Contact Micropipette Ion Selective Electrode for Potentiometric SECM

ELECTROANALYSIS, Issue 10 2007
Gergely Gyetvai
Abstract New solid contact ammonium micropipette electrodes (ISE), well applicable in scanning electrochemical microscopy are reported. The solid contact was made of a PEDOT nanowire coated carbon fiber, lowered down close to the orifice, and dipped inside the cocktail being in the pipette tip. This configuration provided low electrical resistance and good potential stability. Submicron tip size, usual in case of micropipette ISE-s easily can be fabricated in this way. The applicability of the electrode in SECM has been proved in SG/TC mode imaging urease enzyme active spots in urea solutions. [source]

Analysis of Simulated Martian Regolith Using an Array of Ion Selective Electrodes

ELECTROANALYSIS, Issue 15-16 2005
Stefan
Abstract A prototype miniature array of polymer membrane and solid state ion selective electrodes was developed for the purpose of performing an in-situ analysis of the soluble ionic species in Martian regolith (soil). The array contains a total of 27 electrodes for K+, Na+, Ca2+, Mg2+, NH, Ba2+, NO, Cl,, and Li+, each in triplicate. Barium electrodes were used to indirectly monitor sulfate through precipitation by the addition of barium chloride while the lithium electrodes served as a reference for the array by having a constant lithium concentration as a background for all solutions. The array was tested with several types of simulants, soils, and sawdust from a Mars meteorite, all with varying salt content, meant to approximate the various hypotheses regarding the ionic composition of the Martian soil. The activities of anions and cations determined with the array were compared to ion chromatography data. [source]

Evaluation of Cu,Ethylenediamine Metal Ion Buffers as Calibrants for Ion-Selective Electrode Measurement of Copper in Fresh Water Systems

ELECTROANALYSIS, Issue 10 2005
Ling Zeng
Abstract An investigation was made into the accuracy of cupric ion selective electrode (ISE) measurement of Cu in solutions approximating acidic freshwaters with Cu-ethylenediamine buffers used as the calibrants. This method overestimates the free Cu compared with calibration using Cu(NO3)2 standards, the standard addition method, and speciation modelling calculations. Statistical tests showed a small, but significant, difference between the intercepts of the linear Nernstian regressions of the calibration plots of Cu-en buffer standardisation and direct calibration with Cu(NO3)2 standards in matrix that matches the samples. The difference in the intercepts, which corresponds with Eo values of the electrode, is not well understood, but is possibly caused by potentially interfering cations such as Fe2+. The results of this study showed that down to 10,8,M Cu2+, where a linear Nernstian response is possible, the Cu ISE is probably better calibrated using Cu standards prepared in the same matrix as the sample solutions to avoid potential matrix effects. [source]

Ion-Selective Electrodes for Thiocyanate Based on the Dinuclear Zinc(II) Complex of a Bis- N,O -bidentate Schiff Base

ELECTROANALYSIS, Issue 12 2004
Philippe Bühlmann
Abstract An ion selective electrode based on the dinuclear complex formed by two zinc(II) ions and two molecules of the bis- N,O -bidentate Schiff base 2,2,-[methylenebis(4,1-phenylenenitrilomethylidyne)]bisphenol exhibits thiocyanate selectivity with a good discrimination of nitrite, nitrate, and azide. The selectivities of electrode membranes with various compositions indicate that this potentiometric selectivity is based on the formation of a 1,:,1 complex between the thiocyanate anion and the dinuclear ionophore. The 2,:,1 ratio of thiocyanate ions and the dinuclear ionophore that results from higher ratios of cationic sites and ionophore worsens the selectivity, suggesting that binding of a thiocyanate to both zinc(II) centers of the dinuclear ionophore is not favorable. Interestingly, the selectivity patterns of these electrodes differ radically from that of a highly sulfate selective electrode based on a compound reported previously to be the analogous mononuclear 1,:,1 complex of zinc(II) and the same Schiff base. It is suggested that the previously reported 1,:,1 complex with zinc(II) may indeed have been a polymer of the same elemental composition. [source]

Stimulated whole salivary flow rate and composition in menopausal women with oral dryness feeling

ORAL DISEASES, Issue 3 2007
F Agha-Hosseini
The aim of this study was to compare stimulated whole saliva flow rate and composition of menopausal women with/without oral dryness (OD) feeling. A case,control study was carried out in 42 selected menopausal women aged 52,73 years with or without OD feeling (21 as case and 21 as control) conducted at the Clinic of Oral Medicine, Tehran University of Medical Sciences. Paraffin-stimulated saliva samples were obtained by expectoration. The stimulated whole saliva composition was measured by a spectrophotometer [magnesium (Mg+2), calcium (Ca+2), chloride (Cl,), inorganic phosphate (Pi) and total protein], flame-photometry [sodium (Na+)] and ion selective electrode (ISE) [potassium (K+)] methods. No significant differences were found in stimulated whole saliva flow rate, Mg+2, Cl,, Pi, Na+, K+ and total protein concentrations between the two groups, but the mean calcium concentration was significantly higher in cases than in controls (P = 0.003). It seems that the level of salivary calcium concentration may be higher in menopausal women with OD feeling than in the control group. [source]

Nitrite-Induced Methemoglobinaemia Affects Blood Ionized and Total Magnesium Level by Hydrolysis of Plasma Adenosine Triphosphate in Rat

BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2009
Md. Mizanur Rahman
This study was performed on male Sprague,Dawley rats to which NaNO2 was injected (10 mg/kg i.p.) to induce methemoglobinaemia. Methemoglobin (MetHb) in blood was measured before (0 min.) and after 10, 30, 60 and 120 min. of NaNO2 injection. At respective time points, the tMg2+, blood ions and gases were measured by atomic absorption spectrometry and ion selective electrode, respectively. Haematological parameters were checked by automatic blood cell count, and blood films were observed under light microscope. Plasma ATP was measured by bioluminescence assay using a luminometer, and plasma proteins were measured by an automatic analyser. Blood cell count (RBC, WBC and platelet), haematocrit, and haemoglobin were found to be decreased with the advancement of MetHb concentration. With the gradual increase of MetHb concentration, the plasma ATP decreased and blood iMg2+ and plasma tMg2+ increased significantly as time passed by in comparison with the pre-drug values. A significant decrease of the ratio of ionized calcium to iMg2+, Na+ and increase of K+ was observed. In conclusion, NaNO2 -induced methemoglobinaemia is a cause of hydrolysis of plasma ATP which is responsible for the increase of blood iMg2+ and plasma tMg2+ in rats. [source]

Solid Contact Micropipette Ion Selective Electrode II: Potassium Electrode for SECM and In Vivo Applications

ELECTROANALYSIS, Issue 17-18 2009
Gergely Gyetvai
Abstract Micropipette ion selective electrodes are very small, but fragile, short-life time sensors with very high resistance. Their high resistance is a draw back considering application in scanning electrochemical microscopy (SECM) and in life sciences. New, low resistance potassium micropipette electrodes were prepared, and applied. The electrode contains solid internal contact made of a carbon fiber lowered down all the way close to the orifice of the micropipette. The internal contact potential was kept constant by applying a doped, electrochemically prepared PEDOT coating on the fiber surface. The electrode performed well in in vivo experiments both in plant and animal tissue without capacitance neutralization and in SECM. [source]