Zur Thermodynamischen Begründung der Kovats'schen Retentionsindizes

Chromatographia - Ausgehend von den thermodynamischen Grundlagen wird die Siedepunktsabhängigkeit der Retentionszeiten diskutiert. Über eine Formel vonKlages, nach der sich das Quadrat...     

Gas chromatographic determination of estrone,estradiol and estriol in non-pregnancy plasma

Summary A gas Chromatographic method for the determination of estrone, estradiol and estriol in plasma of normal females is described. Purification is done by means of TLC of the free compounds and the acetates and quantitation is achieved by electron capture-gas chromatography of the estrogen heptafluorobutyrates. Experiments on the validation of the method are described along with some examples of its application.

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Zusammenfassung Eine gaschromatographische Methode zur Bestimmung von Östron, Östradiol und Östriol im normalen weiblichen Plasma wurde beschrieben. Die Reinigung erfolgte durch Dünnschichtchromatographie der freien Verbindungen und ihrer Acetate. Die quantitative Bestimmung wurde gaschromatographisch mit Hilfe eines Elektroneneinfangdetektors an Hand der Östrogenheptafluorobutyrate bewerkstelligt. Versuche zur Bewertung dieser Methode sowie Beispiele für ihre Anwendung wurden beschrieben.

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Supported by USPHS Grants AM 09908 and RCDA 5 K 3-AM-31, 321 (S. K.) and a grant from the Ford Foundation.     

Acetals of lactams and acid amides. 35. Synthesis of condensed two- and three-ring pyridine systems on the basis of enamino amides

The synthesis of 2,3,5,6-tetrahydropyrrolo[3,2-c]pyrid-6-one was accomplished by rearrangement of 8H,1-cyano-8-dimethylaminomethylene-2,5,6,7-tetrahydropyrrolo[1, 2-c]pyrimidine. Pyrrolo[3,2-c]pyrimidine, 1,6-naphthyridine, and pyrimido[4,3-b]-azepine derivatives were synthesized on the basis of enamino dinitriles. The hydrolysis of 8H,1-cyano-8-dimethylaminomethylene-2,5,6,7-tetrahydropyrrolo[1,2-c]-pyrimidine in 50% CH₃COOH leads to a pyrrolo[1,2-c]pyrido[4,3-d]pyrimidine derivative. A similar dipyrido[4,3-d-1,2-c]pyrimidine derivative was obtained from 1-cyano-9-dimethylaminomethylene-2,5,6,7,8,9-hexahydropyrido[1,2-c]pyrimidine under these conditions, and 3,4-dioxo-3,4,7,8,9,10-hexahydropyrido[1,2-c]pyrano[4,3-d]-pyrimidine was synthesized bytreatment with a 1 N solution of HCl.See [1] for Communication 34.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 518–522, April, 1982.     

Two types of kinetics of membrane potential of water plant leaves illuminated by ultraviolet light

The effects of ultraviolet-B (UV-B) radiation on plasma membrane of water plant (Elodea canadensis, Vallisneria spiralis) cells were investigated by using microelectrode methods. A fast and reversible depolarization of membrane potential occurs initially during exposure of leaf cells to UV on a white light background, after which a slow phase of depolarization sets in. On action series, UV is pulsed for 15 s, with dark interval of 3 min, no monotonous response of systems on the UV excitation is observed. The action spectrum of the fast UV response lies in the interval of 300-330 nm and that of the slow phase-in the interval of 280-300 nm. The input impedance of membranes remains unchanged during the period of exposure. It is concluded that the H(+)-extruding complex of plant cell plasma membranes really consists of two types of interrelated electronic H(+)-pumps: an H(+)-pump of redox-active nature and the H(+)-pump of the H(+)-ATPase enzyme complex. Clearly, during the exposure of leaf cells to UV light, initially, the H(+)-pump of redox-active nature and then H(+)-ATPase are inhibited. It is proposed that the initial chromophore of UV-B light on plasma membrane can be one of the components of H(+)-pump of redox-active nature. It is probably the molecular of quinone.     

Vibrational circular dichroism: a new spectroscopic tool for biomolecular structural determination

Vibrational circular dichroism (VCD) in the past two decades has developed into a powerful new structural tool. A concise review of the applications of VCD to determine the structures of various biological molecules, namely peptides and proteins, nucleic acids and carbohydrates, is provided.     

Gradient elution capillary electrochromatography and hyphenation with nuclear magnetic resonance

Coupling of gradient capillary electrochromatography (gradient CEC) and capillary zone electrophoresis (CZE) with nuclear magnetic resonance spectroscopy (NMR) was performed using a recently developed capillary NMR interface. This technique was applied for the analysis of pharmaceuticals and food. An analgesic was investigated using isocratic and gradient continuous-flow CEC-NMR. Comparison of the results demonstrated the superiority of gradient CEC over isocratic CEC. Aspartame and caffeine, both ingredients of soft beverages, were separated and analyzed by continuous flow CZE-NMR. The order of elution could be reversed by altering the pH. This reversal led to an increased sample concentration in the NMR detection cell, thus allowing the acquisition of a totally correlated spectroscopy (TOCSY) two-dimensional (2-D) spectrum of the synthetic peptide aspartame.