1,10-Phenanthroline: a versatile building block for the construction of ligands for various purposes

Ionophore incorporated PVC membrane sensors are well-established analyticaltools routinely used for the selective and direct measurement of a wide variety of differentions in complex biological and environmental samples. Potentiometric sensors have someoutstanding advantages including simple design and operation, wide linear dynamic range,relatively fast response and rational selectivity. The vital component of such plasticizedPVC members is the ionophore involved, defining the selectivity of the electrodes' complexformation. Molecular recognition causes the formation of many different supramolecules.Different types of supramolecules, like calixarenes, cyclodextrins and podands, have beenused as a sensing material in the construction of ion selective sensors. Schiff's bases andcrown ethers, which feature prominently in supramolecular chemistry, can be used assensing materials in the construction of potentiometric ion selective electrodes. Up to now,more than 200 potentiometric membrane sensors for cations and anions based on Schiff's bases and crown ethers have been reported. In this review cation binding and anioncomplexes will be described. Liquid membrane sensors based on Schiff's bases and crownethers will then be discussed.

/pdf/schiff-s-bases-and-crown-ethers-as-supramolecular-sensing-437qw0j6rx.pdf

Schiff's Bases and Crown Ethers as Supramolecular Sensing Materials in the Construction of Potentiometric Membrane Sensors

There is a growing production and application of silver nanoparticles (AgNPs) (e.g., in cosmetics products, food technology, textiles and fabrics, and medical products and devices). The rapid growth in the commercial use of AgNPs will inevitably increase exposure to silver in the environment and among the general population. Compared to the vast application of silver, information on the fate, the transformation and the toxicity of AgNPs is very limited. Lack of proper techniques to trace AgNPs in complex matrixes hinders investigation. Thus, development of methods for analysis of AgNPs is very important to achieve detailed insights into the fate, the transport and exposure of AgNPs in environment. This review presents state-of-the-art methods for separation, identification, characterization and quantification of AgNPs. We also discuss perspectives on future developments. (C) 2012 Elsevier Ltd. All rights reserved.

Methods for separation, identification, characterization and quantification of silver nanoparticles

Polymer inclusion membranes: The concept of fixed sites membrane revised

One or two gram aliquots of twelve reference materials with low platinum-group element (PGE) abundances (Ir concentrations ranging from 30 to 510 pg g-1) were analysed by isotope dilution ICP-MS using an on-line chromatographic matrix separation after acid digestion in a high pressure asher (HPA-S) to determine the concentrations of Ru, Pd, Re, Ir and Pt. Osmium concentrations were determined via ID-ICP-MS but as volatile OsO4, whereas Rh concentrations were calculated by comparing the peak areas of the chromatographic peak with that of a standard solution. Validation of the method was performed and the concepts of traceability and measurement uncertainty were applied to assure comparability. The reference materials BCR-2, BHVO-1, BHVO-2, BIR-1, DNC-1, EN026 10D-3, MAG-1, RGM-1, SCo-1, SDO-1, TDB-1 and W-2 were investigated to test for their usefulness for certification. The use of TDB-1 is highly recommended because it is homogeneous at the two gram level and many values based on several different analytical procedures have been published. It is recommended that our efforts should focus on the certification of this reference material to reduce the uncertainties of its currently certified values (Pd and Pt only) and to assign certified values to the other PGE and Re. It is necessary to have at least one well-characterised RM for validation of methods applied to the analysis of PGE and Re in low abundance samples, although the matrix of TDB-1 might not completely match those of many samples.



Des aliquotes de un ou deux grammes de douze materiaux de reference ayant des concentrations basses en elements de la mine du platine (PGE) (concentrations en Ir entre 30 et 510 pg g-1) ont ete analyses par ICP-MS et dilution isotopique, avec separation chromatographique en ligne, dans le but de determiner les concentrations de Ru, Pd, Re, Ir et Pt. Cette analyse etait consecutive a la mise en solution des echantillons par attaque acide dans un creuset a haute pression (HPA-S). Les concentrations en Osmium ont ete determinees par ID-ICP-MS aussi, mais sous la forme volatile OsO4 tandis que les concentrations en Rh etaient calculees en comparant les surfaces des pics chromatographiques a ceux obtenus sur une solution standard. La validation de la methode a ete faite et les concepts de tracabilite et d'incertitude analytique ont ete appliques afin de garantir la comparabilite des resultats. Les materiaux de reference BCR-2, BHVO-1, BHVO-2, BIR-1, DNC-1, EN026 10D-3, MAG-1, RGM-1, SCo-1, SDO-1, TDB-1 et W-2 ont ete testes quant a leur utilite pour une certification. Il en ressort que l'utilisation de TDB-1 est hautement recommandee car il est homogene au niveau de prises de deux grammes et parce que beaucoup de donnees acquises par des procedures analytiques differentes ont dejaete publiees. Il est recommande de focaliser nos efforts sur la certification de ce materiau de reference pour reduire les incertitudes sur les valeurs certifiees actuelles (Pd et Pt seulement) et pour fournir des valeurs certifiees pour les autres PGE et Re. Il est necessaire en effet d'avoir au moins un materiau de reference (RM) bien caracterise pour la validation des methodes appliquees a l'analyse des PGE et de Re dans les echantillons a faible concentration, bien que la matrice de TDB-1 ne soit pas parfaitement representative de celle de beaucoup d'echantillons.

Platinum‐Group Element and Rhenium Concentrations in Low Abundance Reference Materials

Selective transport of silver ion through a supported liquid membrane using some mixed aza-thioether crowns containing a 1,10-phenanthroline sub-unit as specific ion carriers

Highly selective and efficient transport of mercury(II) ions across a bulk liquid membrane containing tetrathia-12-crown-4 as a specific ion carrier

A new PVC membrane electrode for UO 2 2+ ion based on 2,2'-[1,2-ethanediyl bis (nitriloethylidene)]bis(1-naphthalene) as a suitable ionophore was prepared The electrode exhibites a Nernstian response for UO 2 2+ ion over awide concentration range (10 x 10 - 1 -10 x 10 - 7 M) with a slope of 285 ′ 08 mV/decade The limit of detection is 70 x 10 - 8 M The electrode has a response time of < 20 s and a useful working pH range of 3-4 The proposed membrane sensor shows good discriminating abilities towards UO 2 2+ ion with regard to several alkali, alkaline earth transition and heavy metal ions It was successfully used to the recovery of uranyl ion from, tap water and, as an indicator electrode, in potentiometric titration of UO 2 2+ ion with Piroxycam

UO 2 2+ Ion-Selective Membrane Electrode Based on a Naphthol-Derivative Schiff's Base 2,2'-[1,2-Ethandiyl bis(nitriloethylidene)]bis(1-naphthalene)

A facile supported liquid membrane (SLM) system for the selective and efficient transport of silver ion is introduced. The SLM used is a thin porous polyvinyldifluoride membrane impregnated with hexathia-18-crown-6 (HT18C6) dissolved in nitrophenyloctyl ether. HT18C6 acts as a specific carrier for the uphill transport of Ag+ ion as its picrate ion paired complex through the SLM. In the presence of thiosulfate ion as a suitable stripping agent in the strip solution, transport of silver occurs almost quantitatively after 4 h. The selectivity and efficiency of silver transport from aqueous solutions containing other Mn+ cations such as Mg2+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, Hg2+, Fe3+ and Cr3+ ions were investigated.

Gholamhasan Azimi

Papers

Selective transport of silver ion through a supported liquid membrane using some mixed aza-thioether crowns containing a 1,10-phenanthroline sub-unit as specific ion carriers

Highly selective and efficient transport of mercury(II) ions across a bulk liquid membrane containing tetrathia-12-crown-4 as a specific ion carrier

UO 2 2+ Ion-Selective Membrane Electrode Based on a Naphthol-Derivative Schiff's Base 2,2'-[1,2-Ethandiyl bis(nitriloethylidene)]bis(1-naphthalene)

Selective Transport of Silver Ion through a Supported Liquid Membrane Using Hexathia-18-Crown-6 as Carrier

Selective transport of zinc as Zn(SCN)42− ion through a supported liquid membrane using K+-dicyclohexyl-18-crown-6 as carrier