Use of membranes for equivalence point indication-VIII Electrochemical characterization of BaSO(4)-parchment membrane-electrode

Some new aspects of the electrochemical characterization of the BaSO(4)-parchment membrane-electrode are discussed. The electrode function E vs. pH is strongly affected by the ionic strength of the external solution. The electrode is mainly selective for hydrogen, and without interference from sodium ions. The basis of operation of the electrode is selective diffusion. This conclusion is supported by the temperature coefficient, the response rate, and the impedance measurements.     

Spectrophotometric study of the reaction of Hg(II) with cadion A and cadion 2B

The reaction between Hg(II) and Cadion A and Cadion 2B has been studied. Methods are suggested for the determination of Hg(II) in the 0.1-4 ppm range with Cadion A and in the 0.2-8 ppm range with Cadion 2B. Of the 49 ions studied only Hg(I), Sn(II), Br(-), I(-), MnO(-)(4), EDTA, SCN(-), CN(-) and S(2-) interfere. The combination ratios and instability constants of the Hg-Cadion complexes were determined. The structural formulae of the complexes were deduced from the infrared spectra and elemental and thermogravimetric analyses.     

Thermo-indicating paint for damage warning

Thermal analysis coupled with the measurement of temperatures at which colour changes are observed in situ was used to test various inorganic pigments with the aim of introducing them into the compositions of thermo-indicating paints. Through a reversible or irreversible modification of the colour these can indicate an undesired increase in temperature of a fluid in a metallic enclosure. Three such pigments are described, which indicate temperatures of 110, 300 and 400°C. The paint contains the thermo-indicator pigment, soluble glass as binder and either ultrafine silica or silica gel, or a mixture of Na₂SiF₆ and finely-ground sand as hardener. Such paints are used for damage warning.     

Time Evolution of Optical Emission Spectrum of a Hg-HID Lamp Exposed to X-ray

Time variation of optical emission lines for Hg, and other elements detected in a mercury HID lamp before and during X-ray irradiation were analyzed. Various irradiation conditions are causing differences in time dependencies of all Hg spectral line intensities (including that of 253.73 nm resonance line not completely self-absorbed). The X-ray optical depths are smaller in the case of Hg gas compared with burner wall glass. The free electrons generated during X-ray exposure (photoelectrons, Auger electrons) contribute to changes in plasma characteristics (e.g. plasma temperature, density, etc.) in transitory regime. In quasi-stable regime there are practically no differences between electron temperatures for normal and irradiated lamp. A qualitative explanation in the framework of Beer-Lambert law is given.     

Plans for implementation of a quality system in the control laboratory of the Romanian National Medicines Agency

This paper describes the practical implementation of a quality system in the control laboratory of the National Medicines Agency, Romania, the main aim being the alignment of the requirements of the control of drugs in Romania with European Union standards. Activity in this field is relatively new in Romania, however, it is of great importance to Romania’s compliance with international standards. Received: 13 September 2000 Accepted: 19 February 2001     

Beiträge zur Kenntnis der Kolloidchemie der Systeme: Seifen - Kresol - Wasser

Ohne Zusammenfassung Uebersetzt von Hans Erbring (Leipzig).