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Selectivity Coefficients (selectivity + coefficient)
Selected AbstractsThe Current Usage of Selectivity Coefficients for the Characterization of Ion-Selective Electrodes.ELECTROANALYSIS, Issue 12 2003A Critical Survey of the 2000/2001 Literature Abstract The articles describing new ion-selective electrodes published during the years 2000/2001 in eight leading analytical chemistry journals have been surveyed. Compliance with the IUPAC recommendations of the procedures used for characterizing the selectivity of the new electrodes has been checked. It was found that the information accompanying the selectivity data obtained according to the procedures recommended by IUPAC or their variations was frequently insufficient for interpreting of the electrode behavior and comparing with other sets of data, thus reducing the significance of the values provided. Some criteria for improving the communication between researchers in the field are suggested. [source] Novel Potentiometric Sensors of Molecular Imprinted Polymers for Specific Binding of ChlormequatELECTROANALYSIS, Issue 2 2008Ayman Abstract Molecularly imprinted polymers (MIP) were used as potentiometric sensors for the selective recognition and determination of chlormequat (CMQ). They were produced after radical polymerization of 4-vinyl pyridine (4-VP) or methacrylic acid (MAA) monomers in the presence of a cross-linker. CMQ was used as template. Similar non-imprinted (NI) polymers (NIP) were produced by removing the template from reaction media. The effect of kind and amount of MIP or NIP sensors on the potentiometric behavior was investigated. Main analytical features were evaluated in steady and flow modes of operation. The sensor MIP/4-VP exhibited the best performance, presenting fast near-Nernstian response for CMQ over the concentration range 6.2×10,6,1.0×10,2,mol L,1 with detection limits of 4.1×10,6,mol L,1. The sensor was independent from the pH of test solutions in the range 5,10. Potentiometric selectivity coefficients of the proposed sensors were evaluated over several inorganic and organic cations. Results pointed out a good selectivity to CMQ. The sensor was applied to the potentiometric determination of CMQ in commercial phytopharmaceuticals and spiked water samples. Recoveries ranged 96 to 108.5%. [source] Influence of Aprotic Solvent on Selectivity of an Amperometric Sensor with Nafion MembraneELECTROANALYSIS, Issue 5 2006B. Chachulski Abstract This paper presents the results of investigation on selectivity of the sulfur dioxide amperometric sensor with Nafion membrane in the presence of carbon monoxide and nitrogen dioxide as the interferents. There have been compared selectivity coefficients, for the sensors containing the following internal electrolytes: solution of sulfuric acid (concentration 5,mol dm,3) in pure water (A) and solution of sulfuric acid (concentration 5,mol dm,3) in mixed solvent dimethylsulfoxide-water with an DMSO: H2O mole ratio of 1,:,2 (B). Values of the selectivity coefficients have been calculated based on the calibration curves. Analysis of both calibration curves and selectivity coefficients plays a significant role in optimization of a working point of a particular sensor. The investigated sensor operates in a three-electrode system, where the working and counter electrodes are vacuum sublimation deposited on the membrane surface. [source] Numeric Simulation of Ion-Site Association Effects in Ion-Selective Electrode ResponseELECTROANALYSIS, Issue 15-16 2003Konstantin Abstract Effects in ion-selective electrode response and selectivity, caused by ion-site association in membranes are studied by means of numeric simulations based on a generalized model, which does not rely on a certain degree of the dissociation of electrolytes in membranes. The variability of the experimental values of the potentiometric selectivity coefficients is considered in view of the association in membranes. The reasons why the "dissociation approach" often fits experimental data are also discussed. A novel version of segmented sandwich membrane method is proposed for direct potentiometric measurements of ion-site association constants in membranes, and preliminary experimental results are presented. [source] Ion imprinted polymer particles for separation of yttrium from selected lanthanidesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9 2006Ramakrishnan Kala Abstract Lanthanide(III) (Dy, Gd, Tb and Y) ion imprinted polymer (IIP) materials were synthesized via single pot reaction by mixing lanthanide imprint ion with 5,7-dichloroquinoline-8-ol, 4-vinylpyridine, styrene, divinylbenzene and 2,2,-azobisisobutyronitrile in 2-methoxyethanol porogen. The imprint ion was removed by stirring the above materials (after powdering) with 6 mol/L HCl to obtain the respective lanthanide IIP particles. Y-Dy, Y-Gd and Dy-Gd polymer particles were obtained by physically mixing equal amounts of the respective leached individual lanthanide(III) particles. Control polymer (CP) particles were similarly prepared without imprint ion. Application of the above synthesized polymer particles was tested for separation of Y from Dy, Gd and Tb employing batch and column SPE methods using inductively coupled plasma atomic emission spectrometry for the determination. Optimization studies show that Y present in 500 mL can be preconcentrated using Dy-Gd IIP particles and eluted with 20 mL of 1.0 mol/L of HCl, providing an enrichment factor of , 25. Dy-Gd IIP particles offer higher selectivity coefficients for Y over other lanthanides compared to other IIP particles and commercial liquid,liquid extractants. Selectivity studies for Y over other coexisting inorganic species (other than lanthanides) were also conducted and the results obtained show a quantitative separation of Y from other inorganics other than Cu(II) and Fe(III). Furthermore, both batch and column studies indicate the purification of yttrium concentrate from 55.0 ± 0.2 to 65.2 ± 0.2% in a single stage of operation. [source] | ||||||||||