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Marked Selectivity (marked + selectivity)
Selected AbstractsFlow-Through Assay of Quinine Using Solid Contact Potentiometric Sensors Based on Molecularly Imprinted PolymersELECTROANALYSIS, Issue 24 2009Ayman Abstract Miniaturized potentiometric membrane sensors for quinine incorporated with molecular imprinted polymer (MIP) were synthesized and implemented. Planar PVC based polymeric membrane sensors containing quinine-methacrylic and/or acrylic acid-ethylene glycol methacrylate were dispensed into anisotropically etched wells on polyimide wafers. The determination of quinine was carried out in acidic solution at pH,6, where positively charged species predominated prevalently. The suggested miniaturized planner sensors exhibited marked selectivity, sensitivity, long-term stability and reproducibility. At their optimum conditions, the sensors displayed wide concentration ranges of 4.0×10,6,1.0×10,2mol L,1 and 1.0×10,5,1.0×10,2 mol L,1 with slopes of about 61.3,55.7,mV decade,1; respectively. Sensors exhibit detection limits of 1.2×10,6 and 8.2×10,6 mol L,1 upon the use of methacrylic and acrylic acid monomers in the imprinted polymer, respectively. Validation of the assay method according to the quality assurance standards (range, within-day repeatability, between-day variability, standard deviation, accuracy, and good performance characteristics) which could assure good reliable novel sensors for quinine estimation was justified. Application of the proposed flow-through assay method for routine determination of quinine in soft drinks was assayed and the results compared favorably with data obtained by the standard fluorimetric method. [source] An In Situ Copper Plated Boron-Doped Diamond Microelectrode Array for the Sensitive Electrochemical Detection of NitrateELECTROANALYSIS, Issue 20 2005Sarah Ward-Jones Abstract The first example of using a copper microelectrode array for use in electroanalysis is explored and exemplified with the electroanalytical quantification of nitrate. The analytical approach is based upon the in situ deposition of copper at a boron-doped diamond (BDD) microelectrode array. The immobilized copper layer is electrocatalytic for nitrate reduction and exhibits an analytically useful range from 1.2 to 124,,M with a marked selectivity for nitrate ion over nitrate, with a limit of detection of 0.76,,M. The analytical applicability was examined through standard addition determinations of nitrate in drinking and river water samples. [source] Properties of ion channels in the protoplasts of the Mediterranean seagrass Posidonia oceanicaPLANT CELL & ENVIRONMENT, Issue 3 2004A. CARPANETO ABSTRACT Posidonia oceanica (L) Delile, a seagrass endemic of the Mediterranean sea, provides food and shelter to marine organisms. As environment contamination and variation in physico-chemical parameters may compromise the survival of the few Posidonia genotypes living in the Mediterranean, comprehending the molecular mechanisms controlling Posidonia growth and development is increasingly important. In the present study the properties of ion channels in P. oceanica plasma membranes studied by the patch-clamp technique in protoplasts obtained from the young non-photosynthetic leaves were investigated. In protoplasts that were presumably originated from sheath cells surrounding the vascular bundles of the leaves, an outward-rectifying time-dependent channel with a single channel conductance of 58 ± 2 pS which did not inactivate, was selective for potassium and impermeable to monovalent cations such as Na+, Li+ and Cs+ was identified. In the same protoplasts, an inward-rectifying channel that has a time-dependent component with single channel conductance of the order of 10 pS, a marked selectivity for potassium and no permeation to sodium was also identified, as was a third type of channel that did not display any ionic selectivity and was reversibly inhibited by tetraethylammonium and lanthanum. A comparison of Posidonia channel characteristics with channels identified in terrestrial plants and other halophytic plants is included. [source] Oxidation of Aromatic Alcohols in Irradiated Aqueous Suspensions of Commercial and Home-Prepared Rutile TiO2: A Selectivity StudyCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2008Vincenzo Augugliaro Prof. Abstract The photocatalytic oxidation of benzyl alcohol (BA) and 4-methoxybenzyl alcohol (MBA) has been performed in pure water by using commercial TiO2 samples (Sigma-Aldrich, Merck, Degussa P25) and rutile TiO2 prepared from TiCl4 at low temperature. Particular attention has been devoted to the identification of the produced aromatic compounds along with the formed CO2. Oxidation products such as the corresponding aromatic aldehyde and acid, as well as mono- and dihydroxylated aldehydes have been detected. The home-prepared rutile sample showed a marked selectivity towards the formation of the aromatic aldehyde (38 and 60,% for BA and MBA, respectively), resulting in a three- to sevenfold improvement relative to commercial samples, with the only byproduct being CO2. This catalyst was found to be the most selective in the formation of aldehyde in water. By using the commercial or the calcined home-prepared samples, many hydroxylated aromatic compounds were detected besides the aldehyde and the acid. This finding points to a higher selectivity performance of the home-prepared rutile relative to the commercial TiO2 samples. Some of the home-prepared samples were also dialysed to check the influence of the presence of Cl, species on catalyst reactivity and selectivity. We have attempted to explain the different reaction rate and selectivity observed for MBA and BA. [source] | ||||||||||