Identification of low molecular vaporizable components in silicone resins using gas chromatography/mass spectrometry

An experimental set-up for the detection of elemental chlorine in chlorinated hydrocarbons (CHCs) is described based on a miniaturized system, which could be used for on-line monitoring of chlorinated compounds. With an optimized time-resolved detection chlorine from CHCs like CCl₄ can be determined by Laser-Induced-Breakdown-Spectroscopy (LIBS) with g/g-detection limits in the gas phase. The application of a miniaturized Nd : YAG laser resulted only in a minor loss in performance, hence it could be used for designing a rugged and small on-line sensor. In addition, preliminary results for the detection of chlorine via the formation of CuCl in the plasma formed by focussing the laser on a copper surface are reported. Utilizing the luminescence of the CuCl D-system at 440 nm, a tenfold improvement in the detection limits was obtained. It appears that the formation of ad hoc selected, small molecules in a laser plasma could be a promising alternative for the selective and sensitive analysis of gaseous chlorinated and other species.     

Bestimmung wasserlöslicher Polyelektrolyte in Polyurethan-Dispersionen

Zusammenfassung Die Bestimmung wasserlöslicher Polyelektrolyte, die bei der Synthese segmentierter Polyurethanionomerer entstehen, erfolgte durch konduktometrische und potentiometrische Titrationsverfahren nach Abtrennung des Serums durch Ultrazentrifugieren oder Ausfrieren des Polymeren bzw. Abtrennung der wasserlöslichen Elektrolyte mit einem gemischten Ionenaustauscher. Diese Elektrolyte enthielten abhängig von der Rezeptur zwischen 25 und 72% der vorgegebenen Ionenkonzentration. Unterstellt man glatte, kugelförmige Latexpartikeln, so beträgt die Fläche pro festhaftende ionische Gruppe nur 60–170 Ų, wodurch eine erhebliche gegenseitige Beeinflussung der Ionen resultiert.Herrn Prof. Dr. Ing. Dr. h.c. mult. H. Zahn zum 65. Geburtstag gewidtmet (O. L.).     

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The preparation and homogeneity study of synthetic multi-element standards (SMELS) for QC/QA of k0-NAA

Three new synthetic multi-element standards (SMELS) were developed for testing the performance of the k ₀-standardization neutron activation analysis (k ₀-NAA) method when implemented in a laboratory. SMELS consist of a phenol-formaldehyde polymer matrix spiked with different groups of elements according to the half-lives of the formed radionuclides. They are classified as Type I for short-, Type II for medium- and Type III for long-lived radionuclides. This article presents the preparation of SMELS including different aspects such as choice of the matrix and spiking elements, chemical compounds, target concentrations, purity of the matrix and spiking procedure and the homogeneity study for all the spiked elements in order to demonstrate the quality of the produced materials.     

Antimicrobial activity studies of the binuclear metal complexes derived from tridentate Schiff base ligands

Three novel tridentate Schiff base ligands derived fromthe 3-hydroxysalicylaldehyde (H₂L¹), 4-hydroxysalicylaldehyde (H₂L²) and 5-bromosalicylaldehyde (H₂L³) with a new amine N-(pyridyl)-2-hydroxy-3-methoxy-5-aminobenzylamine (2) have been prepared. The ligands and their metal complexes have been characterized by elemental analyses, conductivity and magnetic susceptibility measurements, i.r., electronic absorption and ¹H and ¹³C n.m.r. spectroscopy. All complexes are binuclear and, in some, the H₂O molecules are coordinated to the metal ion. Antimicrobial activities of the ligands and their complexes have been tested against to the Bacillus subtilis IMG 22 (bacteria), Micrococcus luteus LA 2971 (bacteria) Saccharamyces cerevisiae WET 136 (yeast), and Candida albicans CCM 314 (yeast). Thermal properties of all complexes have been studied by t.g. and d.t.a techniques.     

Das Grenzflächenverhalten von Carboxymethylcellulose an Baumwolle

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