Die automatisierte Bestimmung von Kohlenstoff und Wasserstoff. IV

Zusammenfassung Ein Gemisch von-Naphthylisocyanat mit etwa 6 1,4-Diazabicyklo-[2,2,2]-oktan (10–15 ml) reagiert quantitativ und sofort mit mg-Mengen Wasser unter Bildung von Kohlendioxid, das anschließend automatisch titriert wird. Wassermengen von etwa 0,3–3 mg lassen sich in etwa 8 min mit einer Standardabweichung von 0,8% rel. bestimmen.

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The automatic determination of carbon and hydrogen. IV

Summary A mixture of about 10–15 ml of-naphthylisocyanate with about 6%. 1,4-diazabicyclo [2,2,2]-octane reacts instantaneously and quantitatively with water in mg quantities. The resulting carbon dioxide is automatically titrated. Amounts of water of about 0.3–3 mg were determined within 8 min. with a standard deviation of 0.8% rel.

     

Potentiometric determination of fluoride in geological and biological samples following pyrohydrolytic decomposition

A method for the determination of fluoride in coal, coal fly ash, phosphate rock, limestone, mineral clay, fossilised materials, oyster tissue and vegetation using pyrohydrolysis for sample decomposition is proposed. A specific apparatus was constructed and the influence of vanadium pentoxide (V₂O₅) as a catalyst for the pyrohydrolysis reaction was investigated. It was verified that V₂O₅ does not influence the release of fluoride from the vegetation, oyster tissue, coal and coal fly ash matrices analysed. However, the catalyst was necessary for the phosphate rock, fossil bone, mineral clay and limestone samples. Certified and noncertified samples were analysed using an ion selective electrode (ISE) for the analyte detection. Precise (relative standard deviation—R.S.D.<7%) and accurate (recovery in accordance to certified values) results were obtained. The limit of quantification (LOQ) of the method was 5.0 μg g⁻¹ of fluoride using 20 mg of sample and a final dilution to 10 ml. The sample frequency was five samples per hour.     

Activation analysis of geological material using ruthenium as a multiisotopic comparator

The isotopes⁹⁷Ru,¹⁰³Ru and¹⁰⁵Ru, produced by reactor irradiation of elemental ruthenium, were applied as triple comparators in the activation analysis of rock FU-41, a basanitoid from Fuerteventura, Canary Island. The concentrations of the following elements were determined: Sm, Sc, Fe, Co, Na, La, Hf, Eu, Th and Cr. The aim of this work was the experimental control of the error theory of the multiple comparator method as well as the experimental check of the accuracy. Presented at the 3rd Symposium on the Recent Developments in Neutron Activation Analysis, Cambridge (U.K.), 2–4 July 1973.     

Photoreactivity of tiaprofenic acid and suprofen using pig skin as an ex vivo model

The skin is repeatedly exposed to solar ultraviolet radiation. Photoreaction of drugs in the body may result in phototoxic or photoallergic side effects. Non-steroidal anti-inflammatory drugs, such as tiaprofenic acid (TPA) and the closely related isomer suprofen (SUP) are frequently associated with photosensitive disorders; they may mediate photosensitised damage to lipids, proteins and nucleic acids. Using ex vivo pig skin as a model, we investigated the photodegradation of TPA and SUP, and photobinding of these drugs to protein by means of HPLC analysis and drug-directed antibodies. Both with keratinocytes, which were first isolated from the pig skin and thereafter exposed to UVA and with keratinocytes which were isolated from pig skin after the skin was UVA exposed, time-dependent photodegradation of TPA and SUP was found, beside photoadduct formation to protein. The results of this work show that: (a) TPA and SUP were photodecomposed with similar efficiency; major photoproducts detected were decarboxytiaprofenic acid (DTPA) and decarboxysuprofen (DSUP), respectively. (b) Both drugs form photoadducts, as concluded from recognition by drug-specific antibodies. Pig skin appears to be a good model for studying the skin photosensitising potential of drugs.     

Relaxivity and water exchange studies of a cationic macrocyclic gadolinium(III) complex

We conducted relaxometric and water exchange studies of the cationic [Gd((S,S,S,S)-THP)(H2O)]3+ complex (THP 1,4,7,10-tetrakis(2-hydroxy-propyl)-1,4,7,10-tetraazacyclododecane). While the NMRD profiles obtained are typical for DOTA-like complexes (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate), variable-temperature 7O NMR investigations revealed a relatively high water exchange rate (k(298)(ex) = 1.89 x 10(7) s(-1)). These results differ from those reported for other cationic tetraamide macrocyclic Gd(III) complexes, which exhibit characteristically low exchange rates. Since the low exchange rates are attributed partially to the geometry of the M isomer (square antiprismatic) in the tetraamide derivatives, the atypical water exchange rate observed in [Gd((S,S,S,S)-THP-(H2O)]3+ may result from a twisted square antiprismatic structure in this complex and from the relatively high steric strain at the water coordination site as a result of the presence of methyl groups at the alpha-position with respect to the Gd(III)-bound O atoms of THP.     

Effects of Solar UV Radiation on Diatom Assemblages of the Mediterranean

Abstract— Three UV treatments (PAR; PAR + UVA; PAR + UVA + UVB) were performed by placing different UV-ab-sorbing Alters over communities developing on ceramic tiles in a natural marine habitat near Korinthos, Greece. The experiment was repeated at three depths (0.5 m, 1 m, 1.5 m) below the surface of the sea. Differences in community structure due to UV radiation exposure were more pronounced during the early stages of community development. After the first 3 weeks of growth, the productivity of the PAR + UVA + UVB treatment was significantly lower than the PAR + UVA but not than the PAR treatment. This difference did not persist thereafter. At 5 weeks of growth, the productivity at 0.5 m was significantly lower that at 1.0 m. No other significant differences were observed. The findings of the present study suggest that periphytic communities occurring at the upper layers of the euphotic zone may be capable of adjusting to changes in environmental stresses such as by increased solar UVB irradiance.     

An animal model for extracorporeal photochemotherapy based on contact hypersensitivity.

Recently, photopheresis was introduced as a specific immune suppressor in several T cell mediated disorders. In order to study photopheresis, animal models are indispensable. This report describes an easy to handle model for this purpose. It concerns the Wistar-derived rat with contact hypersensitivity (CHS), also a T cell mediated disorder that has already been studied extensively in several other fields of research. After subsequent exposure to 8-methoxypsoralen (8-MOP) and ultraviolet A radiation (UVA), white blood cells from CHS rats were intravenously injected into other syngeneic rats suffering from the same disorder. This treatment appears to be very efficacious in suppressing the immunological response against the applied contact allergen, 2,4-dinitrofluorobenzene (DNFB). Cells subsequently exposed to UVA and 8-MOP did not have any effect.     

Azepines.I : The formation and reactivity of the anion of 2-diethylamino-5-phenyl-3H-azepine

Deprotonation of 2-diethylamino-5-phenyl-3$\text{H}$-azepine with strong bases affords a highly coloured anion, which reacts with deuterium oxide or with an appropriate electrophile to give an azepine bearing the new substituent at C-3.