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  • Analytical Chemistry and Spectroscopy  (100)
  • Physical Chemistry  (8)
  • NMR  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Tutorial to robust statistics (1991)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 5 (1991), S. 1-20 
    Details
    ISSN: 0886-9383
    Keywords: Averaging ; Median ; Outliers ; Regression ; Residuals ; Robustness ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this tutorial we first illustrate the effect of outliers on classical statistics such as the sample average. This motivates the use of robust techniques. For univariate data the sample median is a robust estimator of location, and the dispersion can also be estimated robustly. The resulting ‘z-scores’ are well suited to detect outliers. The sample median can be generalized to very large data sets, which is useful for robust ‘averaging’ of curves or images. For multivariate data a robust regression procedure is described. Its standardized residuals allow us to identify the outliers. Finally, a survey of related approaches is given. (This review overlaps with earlier work by the same author, which appeared elsewhere.)
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180050103
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  • 2
    Electronic Resource
    Electronic Resource
    Physical properties of matrices used for fast atom bombardment (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 492-497 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Physical and chemical properties of common matrices are tabulated, with aims of facilitating rational matrix selection and providing input for fundamental studies of matrix-assisted ionization. The rationale for selecting tabulated properties is discussed.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180708
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  • 3
    Electronic Resource
    Electronic Resource
    1H NMR structure of an antifungal γ-thionin protein SIα1: Similarity to scorpion toxins (1998)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 32 (1998), S. 334-349 
    Details
    ISSN: 0887-3585
    Keywords: antifungal ; thionin ; NMR ; structure ; scorpion ; toxins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The three-dimensional structure of the Sorghum bicolor seed protein γ-thionin SIα1 has been determined by 2D 1H nuclear magnetic resonance (NMR) spectroscopy. The secondary structure of this 47-residue antifungal protein with four disulphide bridges consists of a three-stranded antiparallel sheet and one helix. The helix is tethered to the sheet by two disulphide bridges which link two successive turns of the helix to alternate residues i, i + 2 in one strand. Possible binding sites for antifungal activity are discussed. The same fold has been observed previously in several scorpion toxins. Proteins 32:334-349, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Silanes on magnesium chloride studied by solid-state 29Si-NMR spectroscopy (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2835-2838 
    Details
    ISSN: 0887-624X
    Keywords: NMR ; MAS ; silanes ; Ziegler-Natta ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 29Si cross-polarisation NMR was used to study the interaction between silanes and MgCl2 when co-milled. Large changes are seen for the 29Si chemical shift of the silane between the silane in solution and in the solid complex. Interpretation of the differences in chemical shift are hindered by the absence of an adequate semi-empirical theory. The 29Si chemical shift tensors confirm a strong interaction between the silane and MgCl2. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080311121
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanism of radiation degradation of polyisobutylene (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 971-984 
    Details
    ISSN: 0887-624X
    Keywords: radiation ; polyisobutylene ; NMR ; GC/MS ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: GC, GC/MS, GPC, and Solution NMR spectra were used to study the γ radiolysis of polyisobutylene (PIB) in vacuum to different total doses (0-900 kGy) and at different temperatures (77-423 K). NMR spectra show a large number of new resonances with relatively narrow line widths, and a variety of NMR techniques have been employed to determine and quantify the structures associated with these new resonances. Chemical shift assignments were made by comparison with those for small molecule model compounds and predictions based upon calculations according to several different schemes. Chain-end structures have been proposed that account well for the majority of the new resonances, all being the result of an initial chain scission reaction initiated by the radiation. These assignments support some previous proposals for the mechanism of radiation degradation of polyisobutylene and exclude others. For example, NMR provides no evidence for the formation of ethyl chain ends and some of the main chain unsaturated structures previously proposed. NMR also indicate that at higher doses the chain end products formed during initial stages undergo secondary reactions. GC/MS data show the formation of oligomers during irradiation, which may be due to a backbitting mechanism. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Automated sample cleanup using on-line coupling of size exclusion chromatography to high resolution gas chromatography (1994)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 411-414 
    Details
    ISSN: 0935-6304
    Keywords: Size exclusion chromatography ; Gas chromatography ; Coupled LC-GC ; Cleanup and analysis ; Automation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fully automated on-line sample cleanup system based on the coupling of size exclusion chromatography to high resolution gas chromatography is described. The transfer technique employed is based on fully concurrent solvent evaporation using a loop-type interface, early vapor exit and co-solvent trapping. Optimization of the LC-GC transfer was done visually via an all-glass oven door. To circumvent the problem of mixing within the injection loop, an adaptation was made to the standard loop-type interface. The determination of a series of additives in a polymer matrix is presented as one example of the vast range of applications opened up by this technique.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240170607
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of complex hydrocarbon mixtures using on-line coupling of size-exclusion chromatography and normal-phase liquid chromatography to high-resolution gas chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 125-130 
    Details
    ISSN: 0935-6304
    Keywords: Size-exclusion Chromatography ; Normal-phase liquid chromatography ; Gas Chromatography Coupled LC-LC ; Coupled LC-GC ; Cleanup and analysis ; Group-type separations ; Automation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An on-line coupling of size-exclusion Chromatography (SEC), normal-phase liquid Chromatography (NPLC), and gas Chromatography (GC) for the characterization of complex hydrocarbon mixtures is described. The hyphenated system separates according to size, polarity, and boiling point. The use of size exclusion as the first separation step allows for the direct injection of complex (“dirty”) samples withont prior clean-up. SEC-NPLC coupling was realized using an on-line solvent evaporator based on fully concurrent solvent evaporation (FCSE) using a modified loop-type interface, vapor exit and co-solvent trapping. Complete reconcentration of the analytes was realized by the introduction of a cryogenic cold trap. For the subsequent hydrocarbon group-type separation an ammo-silica column with n-heptane as eluent was used. The NPLC-GC coupling was based on an on-column interface using partially concurrent solvent evaporation (PCSE) and an early vapor exit. Initial results obtained on the analysis of a residue from the atmospheric crude-oil distillation (a so-called long residue) are presented as an example of the enormous separation power of the SEC-NPLC-GC system. The application of the system for quantitative analysis has not yet been studied.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240200302
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  • 8
    Electronic Resource
    Electronic Resource
    Proper Tuning of Comprehensive Two-Dimensional Gas Chromatography (GC×GC) to Optimize the Separation of Complex Oil Fractions (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 182-188 
    Details
    ISSN: 0935-6304
    Keywords: Comprehensive two-dimensional gas chromatography ; GC×GC ; thermal modulation ; oil analysis ; petroleum analysis ; analysis of middle-distillate oil fractions ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Comprehensive two-dimensional gas chromatography (GC×GC) is an utterly suitable separation technique for the analysis of complex samples, such as oil fractions. Once the two columns and the operating conditions are properly tuned, the technique is able to provide a detailed characterization of such materials. Some considerations applying to the tuning of a GC×GC system for a specific separation are presented and discussed. The authors present a number of different column sets and conditions which allow the separation of a non-aromatic hydrocarbon solvent, a kerosene, the light end of a crude oil, and an olefinic fraction, respectively. The highly structured GC×GC chromatograms, together with chemical knowledge about the samples, provide a much more comprehensive characterization of the samples than hitherto possible.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Computerized multiple input chromatography. M. Kaljurand and E. Küllik. Ellis Horwood, Chichester, 1989, 225 pp., ISBN 0-7458-0120-X/0-470-21228-4 (1991)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 14 (1991), S. 566-566 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240140813
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  • 10
    Electronic Resource
    Electronic Resource
    Fast, high precision fingerprinting of fatty acids in milk (1991)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 14 (1991), S. 802-807 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; Sample preparation ; Automation ; Methylation ; Dairy ; Milk ; Lipid ; FAME ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A rapid, precise method has been developed for the determination of the fatty acid profile of small samples of milk fat. Lipids are extracted from milk with n-hexane, triglycerides are trans-esterified with sodium methoxide, and free fatty acids are esterified with methanolic hydrochloric acid. The methyl esters are separated on a narrow-bore, 5% phenyl polydimethylsiloxane capillary column. The fatty acid profile is precise: for the various acids the coefficients of variation of peak area are between 6.7% and 9.7%, with a mean of 8.1%, and the coefficients of variation of peak percentage area are between 0.3% and 5.5% with a mean of 1.8%. The nature of the sample preparation procedure does not limit throughout.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240141205
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