Flow injection analysis for calcium in serum,water and waste waters by spectrophotometry and by ion-selective electrode

The Flow Injection technique is shown to provide fast, reliable and sensitive methods for the determination of calcium in various aqueous as well as serum samples; spectrophotometric or potentiometric detection can be used. At sampling rates of 100–110 samples per hour, with 30-μl sample injections, high reproducibility of measurement and low reagent consumption are achieved in both methods. In the spectrophotometric method, the analytical readout is available within 12 s after sample injection at a total reagent consumption of 0.75 ml per analysis. The potentiometric measurement of the calcium activity in serum is placed on a reliable basis by alternating measurements of serum samples and aqueous standards without incurring any non-reproducible changes in potential between aqueous and serum solutions. This permits the simultaneous determination of pH and pCa, the analytical readout being available within XXX s of sample injection. The good agreement between the results obtained with the Flow Injection method and those attained by atomic absorption and EDTA titrations as well as pCa stat-measurements show that the new methods are potentially suitable for routine analysis.     

Untersuchungen an einigen Einkristallen des Systems CuxHg1–xCr2Se4

Study of Some Single Crystals of the Cu_xHg_1–xCr₂Se₄ System Single crystals of the Cu_xHg_1–xCr₂Se₄ for 0 ≤ x ≤ 0.077 were prepared by the chemical transport method. The crystals were analyzed and investigated by X-rays. Some electric and magnetic properties of the single crystals were determined and the results obtained are discussed.     

Spectrophotometric determination of ruthenium after extraction of perruthenate with benzyltributylammonium chloride

A simple and convenient extractive spectrophotometric method for the determination of ruthenium has been developed. It is based on the oxidation of the different ruthenium (II, III or IV) species to perruthenate with potassium periodate at pH 7.8. The perruthenate is then extracted with benzyltributylammonium chloride in chloroform followed by direct spectrophotometric measurements at 342 and 380 nm. The optimum concentration range was found to be 0.1–5 mg l^–1, the standard deviation ±2.1%. The method has been successfully applied to the determination of ruthenium in organoruthenium compounds.     

Porphyrin acids

The structural change from the porphyrin free base to monoacid and diacid by successive protonation has been studied by the IR, visible and NMR spectroscopy. The results have indicated that the cation and anion of the porphyrin diacid are strongly associated through H-bonding. The far IR spectra show especially marked differences in the free base, monoacid, and diacid due to the changes of the inner core of the porphyrin ring.     

Über Reaktionen von Nitrosophenolen, 4. Mitt.: Reaktion von Nitrosonaphtholen mit Naphtholen

Zusammenfassung Die Reaktion von 1-Nitroso-2-naphthol mit 1-und 2-Naphthol sowie die Reaktion von 2-Nitroso-1-naphthol mit 2-Naphthol in Äthanol und in Äther bei Anwesenheit von HNO₃ gibt 5H-Dibenzo[a,j]phenoxazon-(5) (I), 5H-Dibenzo[a,j]phenoxazon-(5)-14-oxid (II), 5H-Dibenzo[a,h]phenoxazon-(5) (III) sowie 5H-Dibenzo[a,h]phenoxazon-(5)-14-oxid (IV). Es wurde ein Reaktionsmechanismus vorgeschlagen und die Konstitution der hergestellten Verbindungen spektrophotometrisch und potentiometrisch bestimmt.

---

The reaction of 1-nitroso-2-naphthol with 2-and 2-naphthol and the reaction of 2-nitroso-1-naphthol with 2-naphthol in ethanol or ether in the presence of nitric acid have been studied. The main reaction products isolated were the dibenzophenoxazones I–IV. The reaction mechanism for their formation is proposed.

---

---

Mit 4 Abbildungen     

Investigations of aromatic polyesters with polynaphthalene systems in the main chain—VI: NMR studies of the structure of the aromatic copolyesters

Nuclear magnetic resonance spectra of several kinds of terephthalic copolyesters of 4,4′dihydroxydinaphthyl 1,1′ and 2,2 bis(4-hydroxyphenyl) propane were recorded. Proton signals of the terephthalic acid unit corresponding to heterolinkages and homolinkages could be observed in the range from 8.23 to 8.53 ppm. The average sequence lengths and the degrees of randomness in the copolyesters were calculated from the intensities of these signals.     

Solid state spin densities in triplet-exciton TCNQ salts

The combination of molecular spin densities and of structural data is shown to provide a sensitive test for the fine structure splittings and principal axes of triplet spin excitons in organic ion-radical crystals, in support of weakly-perturbed molecular sites in these solids. The exchange pathway in Rb(TCNQ) and the occurrence of dimer radicals, with fractional charges, in several tetrameric (TCNQ)₄^2? stacks illustrate the comparisons afforded by computations of fine structure parameters for triplets states in the solid.     

Air-gap sulfide sensor with super-nernstian response in the low concentration range

An air-gap sulfide sensor is presented which operates on the basis of selective extraction of H₂S from an acidified sample into a small alkaline electrolyte film containing the dicyanoargentate (I) complex. This complex is partly decomposed during the measurement by the absorbed sulfide, and the potential of a silver sulfide-based indicator electrode which is in direct contact only with the electrolyte, then depends on the sulfide concentration of the sample. Because of the extraction and dissociation equilibria, the sensor responds in the low sulfide concentration range with a slope four times larger than that of a normal sulfide electrode. The lower limit of linearity is 10^?8 mol l^?1, because sulfide accumulates in the electrolyte film.     

Greffage radiochimique de l'acrylonitrile dans la masse de films de PTFE

Acrylonitrole can be grafted in the bulk of PTFE films provided the monomer is allowed to diffuse into the grafted zones. For a given radiation dose, the amount of grafting is higher the lower the dose-rate. Even higher grafting efficiencies are reached under conditions of discontinuous irradiations, the reacting mixture being stored in the dark in a thermostat between successive irradiations. The grafting yield is higher the higher the storage temperature. The bulk grafting involves a progressive swelling of the grafted polyacrylonitrile branches by acrylonitrile monomer via a dipole-dipole association of the -CN groups of the monomer with the -CN groups in the polymer.