Die IR-Spektren der Komplexe einiger zweiwertiger Metalle mit 8-Hydroxychinolin

Ohne Zusammenfassung     

Zur gaschromatographischen Bestimmung von ges?ttigten Kohlenwasserstoffen aus Extraktionsbenzin

Ohne Zusammenfassung     

Zur coulometrischen Titration von Phenothiazin in Acetonitril

Ohne Zusammenfassung     

Thermal Cyclization of 2-Acyl-1-azido-3-phenalenones to Phenaleno[1,2-c]isoxazol-7-ones

1-Azido-3-phenalenones 5 with acyl substituents in position 2, obtained by acylation and azidation of 1-hydroxy-3-phenalenones 1 , cyclized by thermolysis to give phenaleno[1,2-c]isoxazol-7-ones 9 . The thermolysis conditions were studied by differential scanning calorimetry.     

?quidensitometrie—eine methode zur beurteilung der struktur von plasmen—X. Untersuchung der zeitlichen und r?umlichen Teilchenverteilung in unipolaren Bogenplasmen1

The axial distribution of the emission and the particle densities of chemical elements was investigated in a pulsed, unipolar arc. The following parameters were varied: polarity and position of the electrodes, electrode gap, ionization potential by using different elements, and the absence or presence of the easily ionizable element Li (as the carbonate). As the method of investigation the authors used poly- and monochromatic photography in connection with photographic equidensitometry. In addition some plasma parameters, such as temperature and electron pressure, were determined. The evaluation was performed partly using photographs that covered integrations over a long period of time and partly with photographs pertaining to separate pulses. A detailed discussion is given of the results, which clearly demonstrate that the directed motion of the ions in the electric field principally governs the axial particle density distribution.     

AAS-Untersuchungen über Verdampfungs- und plasmaprozesse in der Graphitrohrküvette Zur Optimierung der Bestimmungen von Cd-, Zn- und Mn-Spuren in AIIIBV-Halbleiter-Matrices

As a basis for optimizing the analysis conditions for the determination of traces of Cd, Zn and Mn in A^III B^V semiconductor samples by graphite furnace atomic absorption spectrometry (AAS), the authors made a systematic investigation of the matrix effects. The evaporation behaviour of the matrices was studied to assess the possibility of thermal separation of trace element and matrix. Absorption spectra of Ga³⁺ and In³⁺ matrices in 1 N HCl and 1 N HNO₃ between 190 and 330 nm were measured to explain unspecific absorption effects. Intense absorption bands were identified as originating from the diatomic molecules GACl, InCl, GaO and InO. Absorbance vs time curves were determined to study the effects of the matrices on the AA signals. It was established that the formation of diatomic molecules in the gaseous state is a major cause of signal depressions. This effect occurs when the analytes and the matrices or their anionic components evaporate concomitantly. Strong signals depressions were found when the matrices were present in hydrochloric acid (formation of CdCl, ZnCl and MnCl), but not when nitric acid was used. The eventually adopted analytical conditions were chosen so as to make an optimum use of the thermal hydrolysis of the matrices. A detailed discussion of the results is presented and it is shown that direct trace determinations with nitric acid solutions are feasible below the ppm (μg/g) level with a sample size of 0.01 to 0.2 mg.     

Untersuchungen von verdampfungs- und plasmaprozessen in der graphitrohrküvette zur optimierung von AA-bestimmungen—II. Molekülabsorptions-spektrometrische und atomabsorptions-spektrometrische untersuchungen an wäßrigen Lösungen und organischen extrakten des galliums und indiums

The authors compared the sensitivities achieved in the determination of Ga and In by AAS with electrothermal atomization in graphite cuvettes in dependence on the solvent, i.e. some acids and organic extracts. The best sensitivity was found in an HNO₃ environment. Signal depressions were observed especially in the presence of halides and with solvents containing halogens. The results of the investigations showed that the principal cause of the depressions is the formation of stable molecules of the type MX (M = Ga or In; X = Cl or Br) in the gaseous state. A second cause is the evaporation. The temperature, in particular that prevailing during the ashing step affects the X-concentration in the gaseous state because of thermal hydrolysis of unstable salts or evaporation of the organic solvents.     

Atomabsorptionsspektralphotometrische bestimmung von zink in galliumarsenid und galliumaluminiumarsenid

The determination by atomic-absorption spectroscopy of zinc in gallium arsenide and gallium aluminium arsenide is described. In 5–20 mg of sample, 0·1–3 μg of zinc can be determined. The coefficient of variation is 4·5%. The influence of the matrix is described and discussed.