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61.
62.
63.
de la Vaissiere C Luth V Abrams GS Amidei D Baden AR Barklow T Boyarski AM Boyer J Breidenbach M Burchat P Burke DL Butler F Dillon JW Dorfan JM Feldman GJ Gidal G Gladney L Gold MS Goldhaber G Golding LG Hanson G Haggerty J Herrup D Himel T Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Klein SR Lankford AJ Larsen RR LeClaire BW Levi ME Lockyer NS Matteuzzi C Nelson ME Ong RA Perl ML Richter B Ross MC Rowson PC Schaad T Schellman H Schmidke WB Sheldon PD Trilling GH Yelton JM Wood DR 《Physical review letters》1985,54(19):2071-2074
64.
A. Henrion Gunther Dube Wolfgang Richter 《Analytical and bioanalytical chemistry》1997,358(4):506-508
The uncertainty budget of the determination of cholesterol in a reference material (freeze-dried human serum) by isotope
dilution mass spectrometry (IDMS) was evaluated. Measurements were run on a GC/quadrupole MS. A nested experimental design
combined with a corresponding model for the analysis of variance (ANOVA) revealed the components making up the total uncertainty
of the determinations. The coefficient of variation (CV) of the sole GC/MS-step was 0.47%, while that of the sample preparation
including hydrolyzation, extraction and derivatization was 0.84%. This made the in-laboratory (overall) CV 0.96%. In addition,
there was a vial-to-vial effect of 1.00% probably due to both inhomogeneity of the pooled material and lack of reproducibility
of the filling procedure (including freeze drying) of the supplier as well as the reconstitution prior to use in the laboratory.
These contributions sum up to an overall CV of a single determination of about 1.4%.
Received: 17 October 1996/Revised: 14 November 1996/Accepted: 18 November 1996 相似文献
65.
66.
Structure of N-Benzoylthiobenzamide N-Benzoylthiobenzamide forms two polymorphic modifications of which the crystal and molecular structures have been determined by X-ray structure analysis. In both modifications the molecules exist as NH tautomeres, but there are differences with regard to their rotameric configurations. In the monoclinic modification both symmetry independent molecules have a Z,Z′ configuration. The triclinic modification also contains two symmetry independent molecules, but now a Z,Z′ and an E,Z′ configuration exist. All four molecules deviate appreciably from planarity. The results of both structure determinations are compared with each other and with the structure of monothiodibenzoylmethane. 相似文献
67.
68.
W. Koenig F. -W. Richter J. Ch. Bode B. Meinel 《Journal of Radioanalytical and Nuclear Chemistry》1980,58(1-2):327-339
Multi-element-analysis by PIXE in respect to medical applications is discussed. Examples of trace-element determinations in
liver tissues are given, demonstrating the applicability and usefulness of this rather new analytical technique.
相似文献
69.
The introduction of selected fractions from a liquid chromatograph into a gas chromatograph has been described; however, analyses were performed by off-line experiments requiring collection and reinjection of the separate fractions or by on-line procedures where disadvantageously, only a fraction of the separated peak or a well resolved component in a mixture could be introduced into a gas chromatograph. This disadvantage is overcome by the apparatus and method described in this paper, which utilizes a multidimensional chromatography system employing a high efficiency, packed capillary LC column coupled on-line to a capillary gas chromatograph. The liquid chromatograph (so designed) can act as a highly efficient clean-up or chemical class fractionation step prior to introduction into the gas chromatograph, significantly reducing sample preparation times in many applications. Thus minor components in a complex matrix can be determined without prior sample clean-up, an example of which is the determination of polychlorinated biphenyls in a complex hydrocarbon matrix. 相似文献
70.
W. Richter 《Accreditation and quality assurance》1997,2(8):354-359
Primary methods of measurement have a central function in metrology. They are an essential component in the realisation of
the SI units and therefore are indispensable for establishing traceability of measurements of all kinds of physical quantities
to the corresponding SI units. This is also true for chemical analysis. Gravimetry, titrimetry, coulometry, and isotope dilution
mass spectrometry (IDMS) are evaluated with regard to their potential to be primary methods according to a general definition
of primary methods recently given by the Comité Consultatif pour la Quantité de Matière (CCQM). Optical absorption spectrometry
and methods based on colligative properties are also considered. A general scheme for establishing traceability of chemical
measurements to the SI units using primary methods is discussed.
Received: 17 April 1997 · Accepted: 9 August 1997 相似文献