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291.
Simultaneous determination of perhexiline and its monohydroxy metabolites in biological fluids by gas chromatography-electron-capture detection 总被引:2,自引:0,他引:2
R G Cooper G Harper A H Price D A Evans D Lockhart 《Journal of chromatography. A》1986,381(2):305-314
A rapid and sensitive method for the simultaneous determination of perhexiline and its cis-4-axial and trans-4-equatorial monohydroxy metabolites (M1 and M3, respectively) in human plasma, urine and bile is described. The assay utilises a single diethyl ether extraction, heptafluorobutyric acid anhydride derivatisation and separation and detection by gas chromatography-electron-capture detection. The limits of detection are 0.1 microgram/ml for perhexiline and 0.025 microgram/ml for the M1 and M3 metabolites. This method has been used in a five-day kinetic study of three healthy adult males who ingested a single 300-mg dose of perhexiline maleate. One of these volunteer subjects exhibited elevated plasma perhexiline and markedly reduced plasma and urinary M1 concentrations together with profoundly prolonged plasma and urinary M1 elimination times when compared with the other two subjects. These differences are thought to be of genetic origin. There were also obvious differences in urinary M3 concentrations which were discussed. 相似文献
292.
Harper JK Barich DH Hu JZ Strobel GA Grant DM 《The Journal of organic chemistry》2003,68(12):4609-4614
Relative stereochemistry is predicted for ambuic acid using a novel solid-state NMR approach. This NMR technique entails a comparison of measured shift tensor principal values with computed values for all diastereomers, allowing the selection of a best-fit structure. The proposed method extends previous solution NMR structural data by simultaneously modeling with high statistical probability hydrogen-bonding arrangements and molecular conformation at two positions. A dimeric structure is proposed for ambuic acid based on the initial poor fit of the carboxyl carbon tensors to a monomeric model. The dimer model, consisting of hydrogen bonding between pairs of neighboring carboxyl groups, reduces the root mean square error at the carboxy tensor by a factor of 2.7. Lattice details are thus also described by the proposed approach. The structural characterization method presented is of general applicability and may be especially useful for characterizing difficult to crystallize or hydrogen-poor materials. 相似文献
293.
Ioannis Papadakis Lutgart Van Nevel Caroline Harper Yetunde Aregbe Philip D. P. Taylor 《Accreditation and quality assurance》2007,12(2):105-111
The International Measurement Evaluation Programme (IMEP) is an interlaboratory comparison scheme, founded, owned and co-ordinated
by the Institute for Reference Materials and Measurements (IRMM) since 1988. IMEP-12, for the fourth time in the series, focused
on trace elements in water and it was designed specifically to support European Commission directive 98/83/EC. Reference values
for the concentration of ten elements were established with expanded uncertainties according to GUM. In total, 348 laboratories
from 46 countries in five continents participated in the comparison and the degree of equivalence between the results of the
laboratories and the reference values is presented graphically. Samples from the same batch were distributed to ten laboratories
from European Countries, which represented their country in the framework of the EUROMET project 528. Participation in this
comparison was offered to the European Co-operation for Accreditation (EA) for participation of accredited laboratories from
all over Europe in the framework of the collaboration between IRMM and EA and to laboratories from the EU new member states
and acceding countries in the frame of IRMM’s ‘Metrology in Chemistry support program for EU new member states and acceding
countries.’ 相似文献
294.
295.
296.
H. Neubauer A. Kuke K. Solon A. Némec N. W. Lobanow A. M. Sweschnikow F. Brüne Th. Arnd E. Günther A. Poock H. Niklas H. Poschenrieder A. Hock J. Trischler M. Miller L. E. Kießling P. Lohmann K. Ihle W. Stollenwerk S. Gericke E. Doktor W. Sauerlandt W. Lesch A. A. J. v. Śigmond O. Arrhenius J. Lanik Anna Koppová W. R. G. Atkins R. G. Warren A. J. Pugh L. Dworak E. Becker H. Visser F. S. Ssobolew O. Franck G. Sundelin C. Larson S. Osugi S. Yoshie N. Nishigaki P. L. Hibbard H. J. Harper E. Truog B. Dirks F. Scheffer Naehring W. Wöhlbier K. Naumann 《Analytical and bioanalytical chemistry》1935,101(3-4):146-154
297.
298.
This is the first of two papers dealing with the structural solution of physical systems based on infinite periodic minimal
surfaces (IPMS), such as surfactant, lipid-water, and block copolymer systems. In the first paper, the mathematics of minimal
surfaces is briefly reviewed and details of the construction of the associate D, P, and G IPMS are described. Electron density
models of lipid-water systems based on these IPMS are then constructed. The resulting models are then Fourier transformed
to calculate the amplitudes of the first few Fourier terms. These amplitudes are then used to reconstruct the electron density
which is examined and discussed. The subsequent paper will utilize the modeling results to aid in solving the structure of
several real physical systems based on the D surface.
Received 15 January 1999 and Received in final form 20 October 1999 相似文献
299.
Paula P. Bachelor David V. Jordan Warren W. Harper Bret D. Cannon Erin C. Finn 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):873-876
Nitrogen fluorescence induced by radiation can be used to detect the presence of radioactive contamination in the environment.
Contamination quantification from the fluorescence signal requires: the source’s effective alpha spectrum; the specific radiation
quantum fluorescence efficiency; optical attenuation length in air of the fluorescence signal; the absolute throughput and
quantum efficiency of the optical instrumentation; calibration of the instrumentation; and radiation transport modeling of
the “effective” array exposure rate given the alpha particle spectrum. Field testing conducted on optical instrumentation
measured the nitrogen fluorescence yield generated by 241Am alpha emissions. Laboratory studies of 241Am via alpha spectrometry determined whether the presence of solids on source surfaces produced sufficient self-absorption
to decrease fluorescence. Results from the laboratory studies provided correction to the effective alpha-source activity values
in a model of the earlier optical-sensor field measurements, and determined the air fluorescence efficiency of alpha particles
generated by the 241Am sources used in the field experiments. 相似文献
300.
H. F. Wiebe D. R. Harper L. Holborn F. Henning H. L. Callendar E. H. Griffiths C. W. Waidner G. K. Burgess A. L. Day R. B. Sosman L. H. Adams J. Johnston G. Moeller F. Hoffmann W. Meissner J. G. L. Stern Th. W. Richards R. C. Wells W. Meissner Th. W. Richards F. G. Jackson C. Kellner H. F. Wiebe P. Hebe P. Hebe und M. Freund 《Fresenius' Journal of Analytical Chemistry》1913,52(5):304-308
Ohne Zusammenfassung 相似文献