Neutron activation analysis of rhenium in rocks and sediments by extraction chromatography on a pyridine-Kel-F column

A simple method for the determination of rhenium in rocks and sediments has been established. After a neutron-irradiated sample was decomposed by NaOH−Na₂O₂ fusion, the alkaline solution was fed onto a column of the mixed solvent pyridine-benzene (7:3 v/v) supported on Kel-F powder. By passage through the column of 4, 5N NaOH solution which had been equilibrated with the solvent mixture, perrhenate ion remained on the column but other nuclides were eluted. Subsequently, the perrhenate ion on the column could be eluted with a small amount of distilled water, and precipitated as tetraphenylarsonium perrhenate for counting the γ-activity of¹⁸⁶Re. By the present method 0.1 ng of rhenium could be determined with a recovery of 90–95% and an error of ±10%. A part of this work was performed at the Research Reactor Institute, Kyoto University.     

Permeation of high-pressure gases in poly(ethylene-co-vinyl acetate)

A previously proposed theoretical treatment to elucidate the pressure dependence of gas permeability is improved in order to apply it to polymer-gas systems in which gas dissolution follows the Flory-Huggins equation. Permeation rates of N₂, CH₄, and CO₂ in poly(ethylene-co-vinyl acetate) are measured in the pressure range below 90 atm at 10–40°C, and the effect of pressure on permeability is found for each gas. The data are analyzed using the improved method to estimate the contributions of concentration and hydrostatic pressure to the pressure dependence of permeability. The concentration effect decreases with increasing temperature, whereas the hydrostatic-pressure effect is almost independent of temperature. Crystallinity dependence of the concentration effect is discussed in connection with high-pressure permeation data of other semicrystalline polymers reported elsewhere. © 1993 John Wiley & Sons, Inc.     

Sorption,diffusion, and partial molar volumes of C4 hydrocarbons in rubbery polymers

Sorption and dilation isotherms and diffusion coefficients for seven hydrocarbons (n-butane, isobutane, 1-butene, cis-2-butene, trans-2-butene, isobutylene, and 1,3-butadiene) in two rubbery polymers, 1,2-polybutadiene (PB) and poly(ethylene-co-vinyl acetate) (EVAc), were measured at 25°C. Dissolution parameters (Henry's law coefficient and Flory-Huggins interaction parameter), partial molar volumes, and diffusion coefficients were determined. PB exhibited greater affinity and lower diffusivity than EVAc to the C₄ gases, although the gases showed nearly the same partial molar volumes in the two polymers. The diffusivity of such elongated molecules as trans-2-butene in both polymers was higher than that of bulky molecules with similar partial molar volume, such as cis-2-butene and isobutylene. Pressure-dependent permeabilities of PB and EVAc films to the hydrocarbons were predicted and discussed based on the dissolution parameters and the diffusivities. © 1995 John Wiley & Sons, Inc.     

Determination of antimony in solder alloy by hydride generation followed by graphite furnace atomic absorption spectrometry

Summary Antimony was determined in solder alloy (NBS; SRM 1276) by a combination of hydride generation with reducing tube, graphite furnace atomization and atomic absorption detection. Stibines were generated in a horizontal glass tube, in which a pellet of sodium borohydride was placed. 1.2–1.3 1/min of argon flow rate, 2,300° C of atomization temperature and 1.2–2.5 M of acids concentration were the best experimental conditions. The strong supression of the antimony signal by nickel, cobalt and copper was effectively eliminated with 1,10-phenanthroline. A detection limit of 1.2 ng was obtained with a precision of 4–5%. The reducing tube used in this technique is extremely simple and can be connected to all the types of graphite furnaces. Furthermore, this technique can be used for the determination of mercury [1].

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Bestimmung von Antimon in Lotlegierung durch Hydriderzeugung mit nachfolgender Atomisierung im Graphitrohr und AAS-Detektion

Zusammenfassung Antimon wurde nach diesem Verfahren in Lotlegierung NBS (SRM 1276) bestimmt. Die Stibine wurden in einer horizontalen Glasröhre erzeugt, die gekörntes Natriumborhydrid enthielt. Der Argonfluß betrug 1, 2–1,3 l/min, die Atomisierungstemperatur 2300° C und die Konzentration an Säure 1,2–1,5 M. Die starke Unterdrückung des Sb-Signals durch Ni, Co und Cu konnte erfolgreich mit Hilfe von 1,10-Phenanthrolin verhindert werden. Die Nachweisgrenze lag bei 1,2 ng, die Präzision betrug 4–5%. Die benutzte Reduktionsröhre ist sehr einfach und kann an alle Typen von Graphitöfen angeschlossen werden. Das Verfahren läßt sich auch zur Quecksilberbestimmung [1] einsetzen.

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Paper read at the meeting of the Japan Society for Analytical Chemistry, October 1983