Application of Laser-ICP-MS in environmental analysis

Laser sampling inductively coupled plasma mass spectrometry has been used for the quantitative determination of trace elements in samples of environmental significance. Solid sampling in environmental analysis is a very demanding type of application: in fact, the instrumental conditions must be carefully chosen and optimized to minimize signal fluctuations, the vaporized material introduced into the plasma should be representative to the composition of the whole sample and a suitable calibration method must be developed. The analytical problems addressed are: determination of elements in plant ash and their direct determination in growth rings of oaks.     

Synthesis of 6S, 7S-anhydro-serricornine.

Diastereoselective and enantioselective reduction of the β-ketoester $\text{3}$ by yeast to $\text{4}$ provided the chiral starting material for a synthesis of 4RS,6S,7S-serricornine, having the same configuration as the natural product. This material was converted into optically active and diastereomerically pure 6S,7S-anhydro-serricornine ($\text{2}$).     

Bis(diphenylphosphano)alkan- und 1-(Diphenylphosphano)-2-(2-pyridino)ethan-N-Arylsulfinylamin-Nickel(0)-Komplexe

Bis(diphenylphosphano)alkane- and 1-Diphenylphosphano-2-(2-pyridino)ethane-N-arylsulfinylamine Nickel(0) Complexes Synthesis and properties of the bis(diphenylphosphano)alkane-N-phenyl-sulfinylamine-nickel(0) complexes [Ni{Ph₂P(CH₂)_nPPh₂}(PhNSO)] (n = 2 dppe, n = 3 dppp, n = 4 dppb) as well as of the 1-(diphenylphosphano)-2-(2-pyridino)ethane nickel(0) complexes [Ni(dpppe)₂], [Ni(dpppe)(p-TolNSO)] and [Ni(dpppe)(PPh₃)₂] are described. These compounds have been characterized by i. r. and ³¹P n.m.r. spectroscopy. The N-arylsulfinylamine ligands are η²-(N, S)-side on coordinated.     

Synchrotron radiation circular dichroism spectroscopy of ribose and deoxyribose sugars, adenosine, AMP and dAMP nucleotides.

Synchrotron radiation circular dichroism (SRCD) spectra of ribose and deoxyribose sugars, adenosine, AMP and dAMP nucleotides and cyclic derivatives were measured in the vacuum ultraviolet region (down to 168 nm for sugars and 175 nm for adenine derivatives) and at different pH values (3, 6-7, 9-10) and temperatures (between 5 and 45 degrees C). The information content in the VUV region is important since the CD bands strongly depend on the chemical structure of the sugar, the presence and orientation of a phosphate group and the protonation state of adenine. On the other hand, single or double deprotonation of the phosphoric acid group has no influence on the spectra. We assign the vacuum ultraviolet (VUV) CD bands of the nucleoside and nucleotides to be due mainly to n-->pi* transitions in the adenine nucleobase based on a comparison with the absorption spectra. The CD bands of the sugars are due to n(O -->sigma*) transitions and are much smaller than the CD signal from the nucleotides in the VUV region. Bands are assigned to both pyranose and open-chain forms.     

Über Eigenschaften und Reaktivität von Aluminiumtrichlorid · Ethanthiol und Galliumtrichlorid · Ethanthiol

On Some Properties and the Reactivity of Trichloroaluminium · Ethanthiol and Trichlorogallium · Ethanthiol Complexes The synthesis of aluminiumtrichloride · ethanthiol as well as galliumtrichloride · ethanthiol is given. The reactions of these 1:1-adducts with the Lewis bases N(CH₃)₃. P(CH₃)₃, O(C₂H₅)₂ and S(CH₃)₂ and with the compounds (CH₃)₃SiSCH₃ and Pb(SCH₃)₂ are discussed, the reaction products are investigated. Spectra as well as some chemical and physical properties of the starting material and the products are reported.     

Zur Stabilisierung der S?ule elektrischer Lichtb?gen in der Spektralanalyse

Zusammenfassung Es wird ein Überblick über die verschiedenen Maßnahmen zur Stabilisierung von Lichtbögen gegeben. Die einzelnen Methoden werden erläutert und dabei die Unterschiede zwischen magnetischer Stabilisierung und Wandstabilisierung erklärt. Auf ihre Anwendungen in der Spektralanalyse wird eingegangen. Die vom Maecker-Bogen ausgehende, zum scheibenstabilisierten Lichtbogen für die Lösungsanalyse führende Entwicklung wird an zwei Typen dieser Art gezeigt und der grundsätzliche Unterschied in der Aerosolzuführung beider Geräte betont. Die für die Spektralanalyse wichtigen und neuartigen Eigenschaften des scheibenstabilisierten Bogens werden genannt und auf die bis jetzt gewonnenen ausgezeichneten analytischen Erfahrungen hingewiesen.

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Summary The different methods for stabilizing electric arcs are reviewed and explained, and the differences between magnetic stabilization and wall stabilization are elucidated. The application in spectral analysis is dealt with. The development, starting from the Maecker arc and leading to the disc-stabilized arc for the analysis of solutions, is demonstrated with two types of this kind and the fundamental difference in the aerosol supply of both devices is emphasized. The new and for spectral analysis important properties of the disc-stabilized arc are described and the hitherto excellent analytical experiences are pointed out.

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Herrn Prof. Dr. H.Kaiser zum 60. Geburtstag gewidmet.     

Magnetische Protonenresonanz als Hilfsmittel in der Strukturanalyse

Zusammenfassung Mit Hilfe eines größeren Anschauungsmaterials werden die Prinzipien der kernmagnetischen Resonanzspektroskopie für die Protonenresonanz in Hochauflösung dargestellt. Es werden meßtechnische Voraussetzungen aufgeführt, die zu berücksichtigen sind, damit reproduzierbare und eindeutige Ergebnisse erhalten werden. Aus der Praxis werden Beispiele für die Anwendung vor allem unter Hinzuziehung einer zuverlässigen Intensitätskontrolle durch Signalintegration gegeben.Der Verfasser hat Fräulein H. Bracher für die Hilfe bei der Aufnahme von Spektren, vor allem aber Herrn G. Schroth für seine unermüdliche Unterstützung bei der Austestung des Gerätes, der Aufnahme und Auswertung von Spektren und der Zusammenstellung dieser Arbeit herzlich zu danken.Besonderer Dank gilt dem Direktor des Instituts, Herrn Prof. Dr. K. Ziegler, der dieser neuen Methode zu einer Zeit seine uneingeschränkte Förderung hat zuteil werden lassen, als ihre Anwendungsbreite noch nicht ohne weiteres auf der Hand lag.     

Crystal structure of 1-hydroxy-1,2,3-benzotriazolium diphenyl phosphate reveals strong NHO and OHO hydrogen bonds

The structure of 1-hydroxy-1,2,3-benzotriazolium diphenyl phosphate (HOBt/DPP) has been investigated by X-ray analysis. The compound crystallizes in the monoclinic space group P2₁/n with Z = 4 and the following lattice parameters: a = 11.711(2), b = 12.727(2) and c = 12.794(3) Å, β = 105.12(2)°, V = 1840.9(6) ų. The structure was solved by direct methods and refined on F² to R values of wR2 = 0.084 and R1 = 0.034 for 1985 observed reflections. HOBt/DPP has an ionic structure with very short OHO and NHO hydrogen bonds linking the different ions. Owing to these hydrogen bonds, infinite screw-shaped chains which are twisted parallel to the y-axis are formed.