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51.
Max H. Feinberg Christian J. Ducauze 《Fresenius' Journal of Analytical Chemistry》1991,339(9):604-607
Summary Chemometrics have been described as effective tools for exploring chemical data, and many software packages are now available on micro-computers. This work evaluate their suitability for environmental analytical chemistry. Guidelines for multivariate method selection are proposed. They are based on the type of variables and the goal of the study. Two examples are proposed to illustrate these methods and their efficiency. Firstly it is shown that a global assessment of Rhine basin mercuric pollution in the Alsace region is possible with Multiple Correspondence Factor Analysis. Several goals are simultaneously reached: a mapping of pollution, a detection of pollution changes during the study period and an evaluation of bio-accumulation as a function of fish species. Secondly the modeling of industrial soil pollution by heavy metals is studied by Multiple Linear Regression. It demonstrates that chemometrics provide us with necessary tools for environmental analytical chemistry but also for toxicological studies or ecosystem modeling. 相似文献
52.
Karlheinz Ballschmiter Rainer Bacher Angela Mennel Regina Fischer Ulrich Riehle Max Swerev 《Journal of separation science》1992,15(4):260-270
High resolution gas chromatography, with mass selective detection, has been used for the analysis of PCB on methyl 50 % octyl polysiloxane (SB 50 Octyl), methyl octadecyl polysiloxane, and a smectic polysiloxane (SB Smectic); and for the analysis of polychlorodibenzodioxins and polychlorodibenzofurans with 1 to 8 chlorine substituents on 100 % cyanopropyl siloxane (SP 2331), smectic polysiloxane (SB Smectic), a new polar stationary phase (DB-Dioxin). The analysis has also been performed by column coupling. 相似文献
53.
J.Georges Duboudin Michel Petraud Max Ratier Bruno Trouve 《Journal of organometallic chemistry》1985,288(1):C6-C8
Flash pyrolysis of alkyltributyltin acetates, at high temperatures (600–850° C) under a moderate vacuum provides a convenient route to vinyltin derivatives. 相似文献
54.
Lalith Perera Max L. Berkowitz 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,26(1):166-168
We describe here molecular dynamics computer simulations performed to study the solvation of ions (Cl? and Na+) in water clusters. Our simulations show that the calculated structure and dynamics of the clusters is very sensitive to the potential model which is used to describe the interactions. From the comparison with thermodynamic data and data from the photoelectron spectra we conclude that in Cl?(H2O)n (n≤20) clusters the ion is located on the surface of the cluster. 相似文献
55.
Hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, and dodecanoic acid are components of the trail pheromone of the ant species Lasius fuliginosus. The acids were extracted from the contents of the rectal ampullae and identified by the mass spectra and gas chromatographic retention times of the corresponding methyl esters. 相似文献
56.
Max Reckziegel und Gotthard Staats 《Fresenius' Journal of Analytical Chemistry》1965,211(3):173-178
Zusammenfassung Es wird über die Störung der emissionsspektrometrischen Analyse von mineralischen Stoffen durch die Kombination einer Bezugs- und Analysenlinie mit unterschiedlichen Konzentrationsempfindlichkeiten berichtet. Die Störung kann beseitigt werden, wenn die Summe der Atomkonzentrationen der metallischen Komponenten im Aufschluß konstant gehalten wird. Das führt zu einer Variation der Verhältnisse Probe-/Puffermenge, durch die flüchtige Bestandteile und die Summen der Atomkonzentrationen der Proben berücksichtigt werden.
Herrn Dr. O. G. Koch danken wir für freundliche Diskussionen, Herrn L. Krämer für die sorgfältige Ausführung der Versuche. 相似文献
Summary When mineral samples are being analysed by an optical emission method different concentration sensitivities of the element and internal standard lines give rise to a systematic error. To eliminate this error it is necessary to maintain the sum of atomic concentrations of the metallic constituents in the fuse constant by varying the ratio sample size/fluxing agent according to volatile components and the sums of atomic concentrations of the samples.
Herrn Dr. O. G. Koch danken wir für freundliche Diskussionen, Herrn L. Krämer für die sorgfältige Ausführung der Versuche. 相似文献
57.
The intramolecular dynamic behavior of the tetrahedrane-type cluster [Fe2(CO)6(μ-SNH)] 1 was studied by 13C NMR spectroscopy. The 57Fe chemical shift of 1 and the coupling constants 1
J(57Fe,13C) were measured. These NMR parameters, and also 1
J(57Fe,15N), were found to be in good agreement with data calculated by using density functional theory (DFT) methods (B3LYP), based on the geometry calculated at the 6-311+G(d,p) level of theory. The isolobal replacement of the Fe(CO)3 with BH fragments leads to the tetrahedranes [Fe(CO)3(BH)(μ-SNH)] 2 and [(HB)2(μ-SNH)] 3. Both were identified by calculations as minima on the respective potential energy surface (PES). However, the tetrahedrane-type structure of 3 is much higher in energy when compared with the planar cyclic isomers 3a and 3b. 相似文献
58.
The synthesis of 1,2-dihydro[1]benzofuro[2,3-d]pyridazin-1-one and 3,4-dihydro [1]benzofuro[2,3-d]pyridazin-4-one was accomplished by the eyclization of appropriately carbonyl-substituted benzofuran derivatives. Another successful synthetic route was provided using 1,2,3,4-tetrahydro[1]benzofuro[2,3-d]pyridazine-1,4 dione and 1,2,3,4-tetrahydro[1]benzofuro[2,3-d]pyridazin-4-one. The structure of a nitrobenzofuropyridazin-4-one was established using nmr and the nuclear Overhauser effect. 相似文献
59.
Total Synthesis of Natural α-Tocopherol A short and efficient route to optically pure (+)-(3 R, 7 R)-trimethyldodecanol ( 14 ) is demonstrated, 14 serving as side chain unit in the preparation of natural vitamin E. The synthesis of 14 is based on the concept of using a single optically active C5-synthon of suitable configuration and functionalization to introduce both asymmetric centres in 14 . (?)-(S)-3-Methyl-γ-butyrolacton ( 1 ) and ethyl (?)-(S)-4-bromo-3-methylbutyrate ( 2 ), respectively, is used in a sequence of either two Grignard C,C-coupling reactions 5 → 8 and 12 → 13 or two Wittig reactions 17a → 18 and 20 → 21 to achieve this goal. 14 is converted to (2 R, 4′R, 8′R)-α-tocopherol (= vitamin E) by coupling with a chroman unit in known manner. Optical purity of products and intermediates is established. 相似文献
60.
Optimum Obtention of Proferrorosamine A from Pseudomonas roseus fluorescens J. C. MARCHAL 1937. We have developed the best conditions for the culture of Pseudomonas roseus fluorescens, and a quantitative isolation of the Proferrorosamine A produced in the culture solution, in order to study the incorporation of 1-[14C]-glycerol in this propigment. 相似文献