Neue Wege der Analytik durch Kombination der direkten quantitativen Dünnschicht-Chromatographie mit elektronischer Datenverarbeitung

A computer program for direct evaluation of thin-layer chromatograms, which already was described earlier [3] has been tested with a laboratory and some technical formulations of a pesticide. Results have been compared with those obtained by two conventional methods. Mean relative standard deviation calculated from results compiled by electronic data processing (method A) is about 6%, compared to 10% received by graphic method (method C) which is employed by most investigators. In addition, overall time of analysis is 34% higher if graphic method is used. Method A saves time and expense especially in routine analysis because working of the process is easier and may be performed even by assistent personal. The proposed method is suitable for the determination of different active ingredients and impurities even in difficult technical products.     

A study of thin surface layers by multilayer Mössbauer spectroscopy /MMS/

A stacking Mössbauer technique, MMS has been applied for studying thin surface layers. The surface layers formed on the⁵⁷Fe film in aqueous solutions of corrosion inhibitors, such as zinc phosphate and barium metaborate, and in distilled water was studied by this method. It has been found that the corrosion is much slower in the presence of zinc phosphate and barium metaborate. XPS analysis suggests the formation of a mixed iron zinc phosphate on the surface of the⁵⁷Fe film after corrosion in a zinc phosphate solution.     

Über die Reproduzierbarkeit der turbidimetrischen Bestimmung von Phosphorspuren mit Strychninmolybdostickstoff(V)säure

Microchimica Acta - Mit der turbidimetrischen Strychninnitrat-Methode für Phosphorspurenbestimmung nach der Version von Hegedüs und Dvorszky kann man nur dann ausgezeichnete...     

Radionuclide X-ray fluorescence determination of Cr, Fe, Cu, Zn and Pb in industrial wastewaters after preconcentration of determined elements

Radionuclide X-ray fluorescence analysis was used for the determination of Cr, Fe, Cu, Zn and Pb in industrial wastewaters (from surface treatment of metals and glasses) after precipitation of determined elements by 8-hydroxyquinoline.     

Zur Kenntnis von Natrium-hexafluoromanganat(III)

Sodium hexafluoromanganate(III) has been synthesized by heating equimolecular quantities of Na₂MnF₅ and NaF in argon atmosphere. The compound is monoclinic witha=5.56 (1) Å,b=5.84 (1) Å,c=8.10 (2) Å, =90.7 (2) andZ=2. It is a high spin complex with _eff and the deformation of the octahedra is evident from its IR-spectra. Two enantiotropic transitions (at 562 and 653°C) and the melting point at 800°C have been observed.

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8. Mitt.: Mh. Chem.106, 483 (1975).     

Thermal degradation of copolymers of styrene and methyl-vinyl-silane by pyrolysis gas chromatography

Pyrolysis gas chromatographic investigations have been carried out on copolymers of styrene with trimethyl-vinyl-silane and of styrene with dimethyl-phenyl-vinyl-silane, in order to study the mechansims of thermal degradation and the copolymer structures. We have identified the pyrolysis products and measured their relative amounts. The experiments show that the controlling factor in the mechanism of the degradation is the nature of the side-group attached to the carbon atom at which chain scission occurs. If this side-group is phenyl, the main degradation process is depropagation; if it is if it is trimethyl-silyl or dimethyl-phenyl-silyl, intramolecular hydrogen abstraction followed by β scission becomes more important than depropagation. From the point of view of degradation mechanism, the nature of the side-group attached to the carbon atom from which the hydrogen is abstracted is of minor importance.We estimated the average copolymer block length from the amounts of products containing both comonomers as well as from the amounts of trimer composed of the same monomer.     

Discussion on the method for the measurement of the flexural modulus of coupled materials and reasons of the shifts of theQ −1 maxima caused by coupling

Summary When measuringQ ^–1 and the flexural resonance frequency of bars clamped at one end, constituted by a viscoelastic polymeric material glued to a rigid support of modulusE ₁, it is possible to calculate the componentsE ₂ andE ₂ of the complex elastic modulus of the polymeric material examined. In this work the minimum (critical) value of the ratioa=E ₂ /E ₁=a _c and the values of the ratioQ ₂ ^–1/Q ^–1=F ₁ are evaluated beyond which no exact calculation ofE ₂ and ofQ ₂ ^–1 is possible.Within the confidence limits of the linear viscoelasticity theory, these values depend on the accuracy of measurement of both frequency and resonance curve, as well as on the instrument employed, on the operating temperature and on the ratio between the thicknesses of the two coupled materials.In order to keep outside the critical conditions, the most convenient method involves the use of measurements of coupled test-pieces having different ratiosz between their thicknesses and of supports having different modulusE ₁, depending on the field of temperature of the analysis ofE ₂ and tg ₂ concerning and E.P.R. elastomer and a vulcanized cis-1,4 polyisoprene in very wide ranges of temperature comprising the glass transition. Moreover, it is demonstrated by analysis the shift on the temperature axis of the tg maximum of the composite test-piece with respect to the position of the tg maximum of the polymeric material alone.With 11 figures and 1 table