A novel assembly for perfluorinated ion-exchange membrane-based sensors designed for electroanalytical measurements in nonconducting media

A perfluorinated ion-exchange membrane-based sensor suitable for electroanalytical measurements in electrolyte-free media is described, which is assembled following a novel design enabling an easier preparation procedure. It is fabricated by inserting the terminal portion of a working wire electrode into a Nafion tubing of suitable diameter and welding the wire thus wrapped to the bottom of a cell body by an insulating epoxy resin. The remainder upper Dan of the working electrode is covered by a Teflon tubing to avoid the electrical contact with the internal electrolyte introduced into the cell body, which is equipped with a counter and a reference electrode. As a result of this configuration, the actual working-electrode surface is the wire circumference contacted by the polyelectrolyte material at the bottom of the assembly which is exposed to the sample. The performance of this sensor has been tested by cyclic voltammetry, amperometric monitoring and now injection analysis for the electroanalysis of a series of prototype analytes either dissolved in electrolyte-free water (hydrogen peroxide, hydroquinone, ferricyanide, iodide and blomide ions) or present in nitrogen atmospheres (triethylamine and oxygen). Detection limits for these analytes have been estimated for a signal-to-noise ratio of 3, together with the corresponding ranges within which the responses display a linear dependence on the analyte concentration. The results obtained point out that the novel assembly is profitable only for the analysis in electrolyte-free liquid samples, while for the analysis of gaseous atmospheres, especially for flowing gases, ion-exchange membrane sensors prepared by the more usual procedure based on the use of working electrode materials embedded into a moist polyelectrolyte membrane should be preferred

Characterization studies and cytotoxicity assays of Pt(II) and Pd(II) dithiocarbamate complexes by means of FT-IR, NMR spectroscopy and mass spectrometry

The precursors [M(ESDTM)Cl-2] (M = Pt(II), Pd(II); ESDTM EtO2CCH2(CH3)NCS2Me, S-methyl(ethylsarcosinedithiocarbamate)) were synthesized as previously reported [J. Inorg. Biochem. 83 (2001) 31] and used to obtain [M(ESDT)Cl],, (ESDT = ethylsarcosinedithiocarbamate anion) species. The complexes formed through reaction between [M(ESDT)Cl],, and the two chiral amino-alcohols synephryne (Syn) and norphenylephrine (Nor) have been synthesized, with the ultimate goal of preparing mixed dithiocarbamate/amino metal complexes of the type [M(ESDT)(Am)Cl] (Am = Syn, Nor). These compounds have been isolated, purified and characterized by means of FT-IR, mono- and bidimensional NMR spectroscopy and mass spectrometry ESI/ MS (electronspray mass spectra). The experimental data suggest that in all cases coordination of the dithiocarbamate ligand (ESDT) takes a place through the two sulfur atoms, the -NCSS moiety acting as a symmetrical bidentate chelating group, in a square-planar geometry around the M(11) ion, while the other two coordination positions are occupied by the chlorine atom and the amino-alcohol ligand, respectively. In particular, synephrine and norphenylephrine appear to be bound to the metal atom through the amino nitrogen atom by means of a dative bond. Finally, the biological activity of the new complexes has been studied by MTT (tetrazolio salt reduction) test and by detecting the inhibition of DNA synthesis and of clonal growth in various cancer cell lines. All Pd(II) derivatives showed a noticeable activity very close to that of cisplatin, used as reference drug. Moreover, they showed significantly reduced cross-resistance to cisplatin in a pair of cell lines (2008/C13*) with known acquired cisplatin resistance mechanisms

Comparative evaluation of geochemical and geological properties of the surface sediments in selected sities of the Lagoon of Venice

Work carried out under the Project F-ECTS Feed-backs of Estuarine circulation and transport of sediments on phytobenthosConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Osservazioni al SEM della struttura esterna ed interna del tubo calcareo di due famiglie di Serpuloidei (Serpulidae e Sprorbidae)

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal