Nafion® as advanced immobilisation substrate for the voltammetric analysis of electroactive microparticles: the case of some artistic colouring agents

Voltammetry of microparticles is applied to characterise and to identify solid analytes of interest in the field of cultural heritage. Nafion® is used for the immobilisation of solid microparticles onto the surface of a glassy carbon electrode by exploiting the deposition onto the electrode surface of a micro-volume of a suspension of the microsample in polymeric solution. Cyclic voltammetry and square wave voltammetry are applied to characterise and to identify the microparticles immobilised in the Nafion® coating. The analyte studied in this work is Prussian Blue as a typical inorganic pigment, with a relatively simple electrochemical behaviour. The proposed method is applied to a sample of Venetian marmorino plaster. The performance of Nafion® for this analysis is compared with that of the polymer Paraloid B72

Study of the stability of phenol's parenteral solutions

En esta publicación preliminar comunicamos las técnicas analíticas desarrolladas: titulación volumétrica, espectrofotometría UV, colorimetría, separación por cromatografía en capa fina y extracción líquida, a los efectos de controlar la concentración de soluciones parenterales de fenol realizadas entre 2 y 5%In this preliminary publication we impart the analytical techniques performed: volumetric titration, spectrophotometry, colorimetry, separation by thin-layer chromatography and liquid extraction, in order to check the concentration of phenol's parenteral solutions made in 2 to 5%Colegio de Farmacéuticos de la Provincia de Buenos Aire

Study of the stability of phenol's parenteral solutions

En esta publicación preliminar comunicamos las técnicas analíticas desarrolladas: titulación volumétrica, espectrofotometría UV, colorimetría, separación por cromatografía en capa fina y extracción líquida, a los efectos de controlar la concentración de soluciones parenterales de fenol realizadas entre 2 y 5%In this preliminary publication we impart the analytical techniques performed: volumetric titration, spectrophotometry, colorimetry, separation by thin-layer chromatography and liquid extraction, in order to check the concentration of phenol's parenteral solutions made in 2 to 5%Colegio de Farmacéuticos de la Provincia de Buenos Aire

Study of the stability of phenol's parenteral solutions

En esta publicación preliminar comunicamos las técnicas analíticas desarrolladas: titulación volumétrica, espectrofotometría UV, colorimetría, separación por cromatografía en capa fina y extracción líquida, a los efectos de controlar la concentración de soluciones parenterales de fenol realizadas entre 2 y 5%In this preliminary publication we impart the analytical techniques performed: volumetric titration, spectrophotometry, colorimetry, separation by thin-layer chromatography and liquid extraction, in order to check the concentration of phenol's parenteral solutions made in 2 to 5%Colegio de Farmacéuticos de la Provincia de Buenos Aire

How the morphology of nafion-based membranes affects proton transport

This work represents a systematic and in-depth study of how Nafion 1100 membrane preparation procedures affect both the morphology of the polymeric film and the proton transport properties of the electrolyte. The membrane preparation procedure has non-negligible conse-quences on the performance of the proton-exchange membrane fuel cells (PEMFC) that operate within a wide temperature range (up to 120 °C). A comparison between commercial membranes (Nafion 117 and Nafion 212) and Nafion membranes prepared by three different procedures, namely (a) Nafion-recast, (b) Nafion uncrystallized, and (c) Nafion 117-oriented, was conducted. Electrochemical Impedance Spectroscopy (EIS) and Pulsed-field gradient nuclear magnetic reso-nance (PFG-NMR) investigations indicated that an anisotropic morphology could be achieved when a Nafion 117 membrane was forced to expand between two fixed and nondeformable surfaces. This anisotropy increased from ~20% in the commercial membrane up to 106% in the pressed membrane, where the ionic clusters were averagely oriented (Nafion 117-oriented) parallel to the surface, lead-ing to a strong directionality in proton transport. Among the membranes obtained by solution-cast, which generally exhibited isotropic proton transport behavior, the Nafion uncrystallized membrane showed the lowest water diffusion coefficients and conductivities, highlighting the correlation between low crystallinity and a more branched and tortuous structure of hydrophilic channels. Fi-nally, the dynamic mechanical analysis (DMA) tests demonstrated the poor elastic modulus for both uncrystallized and oriented membranes, which should be avoided in high-temperature fuel cells