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  • Analytical Chemistry and Spectroscopy  (1,785)
  • Physical Chemistry  (334)
  • Wiley-Blackwell  (2,119)
  • American Institute of Physics (AIP)
  • American Meteorological Society
  • Cell Press
  • 1995-1999  (451)
  • 1990-1994  (1,668)
  • 1999  (132)
  • 1997  (319)
  • 1992  (1,668)
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  • Wiley-Blackwell  (2,119)
  • American Institute of Physics (AIP)
  • American Meteorological Society
  • Cell Press
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  • 1995-1999  (451)
  • 1990-1994  (1,668)
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  • 1
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    Details
    ISSN: 0886-9383
    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/cem.1180060201
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  • 2
    Electronic Resource
    Electronic Resource
    Diary (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. i 
    Details
    ISSN: 0886-9383
    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/cem.1180060202
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  • 3
    Electronic Resource
    Electronic Resource
    Editorial (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 63-64 
    Details
    ISSN: 0886-9383
    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/cem.1180060204
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  • 4
    Electronic Resource
    Electronic Resource
    A new receptor model: A direct trilinear decomposition followed by a matrix reconstruction (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 65-83 
    Details
    ISSN: 0886-9383
    Keywords: Trilinear decomposition ; Receptor modeling ; Source identification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In many cases, monitoring data for ambient airborne particles can be organized in the form of a three-way data table with one way for chemical species, one for sampling periods and one for sites. A direct trilinear decomposition followed by a matrix reconstruction (DTDMR) is developed to analyze such a data table as a whole. The three-way data set is composed into three two-way matrices by a direct trilinear decomposition (DTD). The column vectors of each of the matrices are called ‘source profiles’, ‘emission patterns’ and ‘site coefficients’ respectively. Particulate sources are identified by examining both their source profiles and emission patterns. After the sources have been identified, emission patterns and site coefficients are used to produce a three-way matrix that gives estimates of mass contributions of sources to the samples collected at every site in every period. By simulation study, not only has the method been verified, but a good indicator has been found that shows the number of factors (i.e. sources) in the system. Unlike other receptor models, DTDMR does not require source profile data and does not involve trial-and-error procedures. Since DTDMR identifies sources based on variations in two dimensions, it has a higher potential to distinguish two sources that have similar chemical compositions. The DTDMR model has provided excellent results with simulated data and has been applied in a real world three-way data set.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180060205
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  • 5
    Electronic Resource
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    The chemometrics group, University of Bergen, Norway (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 113-116 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180060209
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  • 6
    Electronic Resource
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    In memoriam: Herman Wold, pioneer of PLS (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 117-118 
    Details
    ISSN: 0886-9383
    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/cem.1180060303
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  • 7
    Electronic Resource
    Electronic Resource
    Wavelength selection in multicomponent near-infrared calibration (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 151-161 
    Details
    ISSN: 0886-9383
    Keywords: NIR spectroscopy ; Wavelength selection ; Interaction effects ; Multicomponent mixtures ; Partial least squares ; Generalized least squares ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modern scanning (near-)infrared reflectance/absorption (NIR) spectroscopes measure the absorptions or reflectances at a sequence of around 1000 wavelengths. Training data may consist of 10-100 carefully designed sample mixtures for which the true composition of the mixture is either known by formulation or accurately determined by wet chemistry. In future one wishes to predict the true composition from the spectrum. In this paper we compare a simple wavelength selection approach with methods which retain all the wavelengths. It offers a powerful yet simple technique for choosing those wavelengths that are specific to each pure component as against the other components (including the medium) for the varying compositions. In the presence of a defined range of ingredients in thus chooses wavelengths which are highly selective for each particular component. It has the added advantage of selecting wavelengths which are little effected by interaction effects and consequent non-linearities.The calibration data used consist of 125 observations of three sugars, each varying at five levels in a full 53 design. The validation set consists of 21 further samples specially selected to have compositions outside the range of the training sample. The selection methods perform much better on this prediction set than methods which retain all the wavelengths, 700 in this case. The leave-one-out cross-validation internal to the calibration data would point to the opposite finding and suggests that such crossvalidations may be overly flattering to techniques such as partial least squares and may encourage overfitting. After selection, simple straightforward least squares methods may be used, eschewing the need for ‘shrinkage’ methods such as partial least squares or ridge regression.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060306
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  • 8
    Electronic Resource
    Electronic Resource
    Data analysis with minimal assumptions (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 247-255 
    Details
    ISSN: 0886-9383
    Keywords: Analysis of variance ; Assumptions ; Graphics ; Models ; Validation of model ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The computer has made it possible to scrutinize data rapidly by means of graphics. This should be done prior to the application of any model to the data, since the model must be validated before using it as a means of analyzing the data. The procedure is illustrated in terms of two examples of real experimental data.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060504
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  • 9
    Electronic Resource
    Electronic Resource
    Design and optimization in organic synthesis, Rolf Carlson, Elsevier, Amsterdam ISBN 0-444-89201-X, No. of pages: 552, price: 330 f1 (1992) (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 284-285 
    Details
    ISSN: 0886-9383
    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/cem.1180060508
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  • 10
    Electronic Resource
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    Quadratic PLS regression (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 307-334 
    Details
    ISSN: 0886-9383
    Keywords: Non-linear PLS ; Quadratic regression ; Non-linear models ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We treat here an extension of linear PLS regression to include regression on quadratic PLS components. The quadratic regression can be viewed as a natural extention of linear PLS regression to quadratic PLS according to the H-principle of mathematical modelling. The numerical implementation is treated in detail. It is shown that this approach can be used for models with large numbers of variables. Some modelling strategies are discussed depending on the purpose of the modelling. Applications of this approach are treated.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180060603
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  • 11
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    Software Review (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 357-357 
    Details
    ISSN: 0886-9383
    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/cem.1180060606
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  • 12
    Electronic Resource
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    Masthead (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    Details
    ISSN: 0886-9383
    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/cem.1180060101
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  • 13
    Electronic Resource
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    Window factor analysis: Theoretical derivation and application to flow injection analysis data (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 29-40 
    Details
    ISSN: 0886-9383
    Keywords: Factor analysis ; Window factor analysis ; Multicomponent analysis ; Flow injection analysis ; Self-modeling curve resolution ; Bismuth chloride complexes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Window factor analysis (WFA) is a self-modeling method for extracting the concentration profiles of individual components from evolutionary processes such as flow injection, chromatography, titrations and reaction kinetics. The method takes advantage of the fact that each component lies in a specific region along the evolutionary axis, called the window. Theoretical equations are derived. The method is used to extract the concentration profiles and spectra of seven bismuth species from data obtained by Gemperline and Hamilton, who injected bismuth perchlorate into a flowing stream of hydrochloric acid.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060104
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  • 14
    Electronic Resource
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    The relationship of closure, mean centering and matrix rank interpretation (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 57-62 
    Details
    ISSN: 0886-9383
    Keywords: Closure ; Baseline ; Mean centering ; Rank ; Exploratory data analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes an investigation into the relationship of closure, a baseline offset and mean centering to the interpretation of matrix rank. The equivalence of a certain type of closure to a constant baseline (i.e. a simple numerical offset which may vary between response channels but is constant over all samples) is demonstrated. A systematic approach to the interpretation of the rank of a matrix is given.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060106
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  • 15
    Electronic Resource
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    Ranking principal components to reflect group structure (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 97-102 
    Details
    ISSN: 0886-9383
    Keywords: Between-group variances ; Canonical variate criterion ; Eigenvalues ; Eigenvectors ; Orthogonal projection ; Within-group variance ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Canonical variate analysis is the appropriate descriptive technique for multivariate data which have an a priori group structure, but problems arise with this technique when there are more variables than within-group degrees of freedom because of singularity of matrices. In such cases it is shown through illustrative examples that principal component analysis is a viable substitute provided that the principal components are ranked according to the canonical variate criterion (ratio- of between- to within-group variances) rather than the usual criterion of total variance. This ranking can also be used to select components for subsequent discriminant analysis.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060207
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  • 16
    Electronic Resource
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    Masthead (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    Details
    ISSN: 0886-9383
    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/cem.1180060301
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  • 17
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    Classification of mass spectra (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 119-133 
    Details
    ISSN: 0886-9383
    Keywords: Mass spectra ; Classification ; Structure description ; Fragmentation ; Ion series ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to investigate correlations between the functionality of compounds and the classification of their mass spectra, low-resolution spectra of monofunctional compounds have been classified by four supervised classification methods. The new classes are characterized by structural features and the correlation between functionality and classification is explained by fragmentation rules. Systematic misclassifications show that low-resolution mass spectra alone are not suitable for reliable identification of functionality.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060304
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  • 18
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    Multiple-correspondence analysis optical microscopy for determination of starch granules (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 163-175 
    Details
    ISSN: 0886-9383
    Keywords: Multiple-correspondence analysis ; Starch granule description ; Image analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raw starch is composed botanically of characteristic granules of various sizes and shapes, so that each kind of starch may be characterized by the population of its granules. In the present study ten commercial starch species were studied: wheat, rice, manioc, potato, arrowroot, amylomaize, normal maize, waxy maize and two different banana species. Six variables measuring the size and shape of granules were obtained by image analysis. The objective was to find a method to describe and compare the granule populations of the ten species. For such a study, multiple-correspondence analysis (MCA) was applied. MCA makes it possible to draw similarity maps of categories and objects. For each starch species the frequency distributions (histograms) of the six variables were assessed and each granule was characterized by its species and the classes of histograms to which it belonged. MCA was applied to the granule table and a description of the histogram classes and the granules was obtained. From the variables description a general typology of the granules was deduced. The similarity maps showed considerable scatter of the granules for all species except rice. A particular species could therefore not be identified by a single granule, but the granule distribution seemed to be characteristic. MCA was an appropriate method to analyse these data because it points out non-linear relationships between quantitative and qualitative variables.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060307
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  • 19
    Electronic Resource
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    Estimation of prediction error for samples within the calibration range (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 177-188 
    Details
    ISSN: 0886-9383
    Keywords: PLS ; Prediction error ; Background constituents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modification of a technique proposed by Lorber and Kowalski for the estimation of prediction errors is presented. The method is applied to five data sets. The results show that for some data sets the estimated prediction errors are close to the actual prediction errors for samples within the calibration range, while samples outside the calibration range must be background corrected before quantification of the prediction error.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060403
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  • 20
    Electronic Resource
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    A robust PLS procedure (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 189-198 
    Details
    ISSN: 0886-9383
    Keywords: Robust regression ; Partial least squares ; QSAR ; Perturbation study ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A robust partial least squares (PLS) regression algorithm is developed. This is achieved by substitution of the univariate regression steps in the iterative PLS2 algorithm by a robust alternative. The angle between loading vectors from both perturbed and unperturbed solutions is used as a measure of robustness. By means of a perturbation study on a structure-activity data set, it is demonstrated that the stability of the robust method is superior to standard PLS.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060404
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  • 21
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    Sequential simplex optimization, Fredrick H. Walters, Lloyd R. Parker Jr., Stephen L. Morgan and Stanley N. Deming, CRC Press, Boca Raton, FL, 1991, 325 pages, ISBN-8493-5894-9, $49.95 (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 227-227 
    Details
    ISSN: 0886-9383
    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/cem.1180060407
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  • 22
    Electronic Resource
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    Masthead (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    Details
    ISSN: 0886-9383
    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/cem.1180060501
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  • 23
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    Genetic algorithms as a strategy for feature selection (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 267-281 
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    ISSN: 0886-9383
    Keywords: Genetic algorithms ; Feature selection ; Multivariate analysis ; Optimization methods ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Genetic algorithms have been created as an optimization strategy to be used especially when complex response surfaces do not allow the use of better-known methods (simplex, experimental design techniques, etc.). This paper shows that these algorithms, conveniently modified, can also be a valuable tool in solving the feature selection problem. The subsets of variables selected by genetic algorithms are generally more efficient than those obtained by classical methods of feature selection, since they can produce a better result by using a lower number of features.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060506
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  • 24
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    Mathematical model for the optimization of the reaction between 2,3-bis(m-tolyl)quinolizinium bromide and piperidine using a factorial design (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 1-10 
    Details
    ISSN: 0886-9383
    Keywords: Derivatization reaction ; Factorial design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of nucleophiles have been successfully identified and quantified using the Kröhnke reaction with 2,3-diphenyl derivatives of quinolizinium salts. Optimization of the reaction conditions by means of a mathematical model involving analysis of the response surface has led to a better understanding of the factors exerting an influence on the above reaction.The parameters chosen were temperature, reaction time, base concentration, water concentration and nucleophile concentration. The reaction was developed in polar aprotic solvents (acetone, acetonitrile). To facilitate the nucleophilic attack, the presence of an organic base (triethylamine) was necessary, although concentrations in excess of 0·15M did not alter the development of the reaction. Since pharmaceutical solutions are often aqueous, the influence of water on the reaction was studied. Low water volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilic reagent. However, when the water proportion exceeded that of the organic solvent, the fluorescence intensity was lower than expected. Development of the fluorescent reaction product was first detected 5 min after the reaction started. The fluorescence intensity reached its optimum value after 138 min.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060102
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    Announcements (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. i 
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    ISSN: 0886-9383
    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/cem.1180060203
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  • 26
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    Computer-generated multicomponent calibration designs for optimal analysis sample predictions (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 85-96 
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    ISSN: 0886-9383
    Keywords: Optimization ; Calibration ; Simulated annealing ; Experimental design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper utilizes variable step size generalized simulated annealing (VSGSA) to design multicomponent calibration samples for spectroscopic data. VSGSA is an optimization procedure which is capable of converging to exact positions of global optima located on multidimensional continuous functions. On the basis of analysis sample response vectors, optimally designed calibration concentration matrices are obtained assuming knowledge of components present. The complexity of response surfaces established by the optimization criteria is described.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060206
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  • 27
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    The effect of mean centering on prediction in multivariate calibration (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 103-111 
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    ISSN: 0886-9383
    Keywords: Mean centering ; Preprocessing ; Multivariate calibration ; Error propagation ; Principal component regression (PCR) ; Partial least squares (PLS) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Traditionally, one form of preprocessing in multivariate calibration methods such as principal component regression and partial least squares is mean centering the independent variables (responses) and the dependent variables (concentrations). However, upon examination of the statistical issue of error propagation in multivariate calibration, it was found that mean centering is not advised for some data structures. In this paper it is shown that for response data which (i) vary linearly with concentration, (ii) have no baseline (when there is a component with a non-zero response that does not change in concentration) and (iii) have no closure in the concentrations (for each sample the concentrations of all components add to a constant, e.g. 100%) it is better not to mean center the calibration data. That is, the prediction errors as evaluated by a root mean square error statistic will be smaller for a model made with the raw data than a model made with mean-centered data. With simulated data relative improvements ranging from 1% to 13% were observed depending on the amount of error in the calibration concentrations and responses.
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    URL: http://dx.doi.org/10.1002/cem.1180060208
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  • 28
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    Diary (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. i 
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    ISSN: 0886-9383
    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/cem.1180060302
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  • 29
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    Multivariate analysis of 2D surfaces: Folding and interpretation (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 135-150 
    Details
    ISSN: 0886-9383
    Keywords: 2D surface ; Multivariate analysis ; Non-congruent ; Unfolding ; Folding ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of latent variable projection for analysis of non-congruent 2D surfaces is presented. We give a formal description of the folding/unfolding process. A simulated 2D oscillator evolving in time is studied in detail to illustrate interpretation aspects of the method.
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    Diary (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. i 
    Details
    ISSN: 0886-9383
    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/cem.1180060402
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    MARS: A tutorial (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 199-216 
    Details
    ISSN: 0886-9383
    Keywords: MARS ; Splines ; Multivariate calibration ; Non-linear ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This tutorial paper presents a simplified view of one of the more recently published multivariate calibration methods particularly suited to dealing with non-linear data sets. The method is referred to as MARS and stands for multivariate adaptive regression splines. Simple examples are provided to explain the workings of the method.
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    URL: http://dx.doi.org/10.1002/cem.1180060405
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    Chemometrics: Applications of mathematics and statistics to laboratory systems, R. G. Brereton, Ellis Horwood, Chichester, ISBN-0-13-131350-9, 307 pp., £54.50, (1990) (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 228-228 
    Details
    ISSN: 0886-9383
    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/cem.1180060408
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    Software news (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 229-229 
    Details
    ISSN: 0886-9383
    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/cem.1180060409
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    On the integration of kinetic models using a high-order taylor series method (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 231-246 
    Details
    ISSN: 0886-9383
    Keywords: Integration methods ; Taylor series method ; Optimization methods ; Kinetic mechanisms ; Kinetic determinations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general equation to derive kinetic models up to any order is given. This equation greatly facilitates the application of the Taylor series method to the integration of kinetic models up to very high orders. When dealing with non-stiff models, computing time is always reduced by increasing the integration order, at least up to the 20th order. When the model is stiff, the integration order should be optimized; however, a twelfth order is recommended to integrate weakly stiff models. The use of an algorithm which permits the immediate calculation of the integration step size required to maintain a given accuracy leads to further reductions in computing time. When implemented as recommended here, a high-order Taylor series method is more rapid and accurate than Runge-Kutta and predictor-corrector methods and can be advantageously used in combination with optimization methods to perform mechanism studies and in multicomponent kinetic determinations.
    Additional Material: 6 Ill.
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    Three-dimensional chemical structure handling, Peter Willett, Research Studies Press, Taunton, Somerset, UK, 1991, ISBN 00 86380 121 8 (Wiley Inc. 0 471 93108 X), 241 pp (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 283-284 
    Details
    ISSN: 0886-9383
    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/cem.1180060507
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    A review of three-dimensional chemical structure retrieval systems (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 289-305 
    Details
    ISSN: 0886-9383
    Keywords: Chemical structure database ; Conformational searching ; Similarity searching ; Substructure searching ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper presents a review of the rapid developments that have taken place over the last few years for the searching of databases of three-dimensional (3D) molecules. The geometric arrangement of the atoms in a 3D molecule is described by an interatomic distance matrix. This is a form of labelled graph that can thus be searched using the subgraph-isomorphism algorithms that are widely used for searching databases of two-dimensional (2D) molecules. Several in-house and commercial systems have been developed for 3D database searching that are based on such techniques. These systems are reviewed and their effectiveness demonstrated by examples of their use in the discovery of novel, biologically active molecules. Current systems represent a molecule by one or a small number of low-energy conformations and there is hence much interest in the development of representational techniques and searching algorithms that account for the full set of geometric arrangements that can be adopted by a flexible molecule.
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    Masthead (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    Details
    ISSN: 0886-9383
    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/cem.1180060601
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    Predictive ability of regression models. Part II: Selection of the best predictive PLS model (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 347-356 
    Details
    ISSN: 0886-9383
    Keywords: GOLPE ; PLS ; Regression ; SDEP ; Variable selection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure called GOLPE is suggested in order to detect those variables which increase the predictivity of PLS models. The procedure is based on evaluating the predictive power of a number of PLS models built by different combinations of variables selected according to a factorial design strategy. Examples are given of the efficiency of this variable selection procedure, which shows how these predictive PLS models are better than those obtained by all variables and better than the corresponding ordinary regression models.
    Additional Material: 3 Ill.
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    Simple validatory tools for judging the predictive performance of parafac and three-way PLS (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 11-28 
    Details
    ISSN: 0886-9383
    Keywords: Three-way PLS ; PARAFAC ; Unfolding ; Validatory tools ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methods PARAFAC and three-way PLS are compared with respect to their ability to predict reversed-phase retention values. Special attention is paid to simple validatory tools, the meaning and use of which are explained.
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    Principal variations in the chemical composition of peat: Predictive peat scales based on multivariate strategies (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 41-56 
    Details
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The principal properties, here called the ρ-scales, of peat have been calculated on the basis of chemical analysis. The scales were derived from quantitative contents of carbohydrates, Klason lignin, amino acids, amino sugars and conventional chemical peat measurements. The variation in the chemical parameters was compressed using principal component analysis (PCA). Partial least squares (PLS) regression was used for prediction of botanical, microbial, physical and dewatering data. A rapid estimation of the scales has been made from near-infrared (NIR) spectroscopy and offers, indirectly, rapidly obtainable, chemically interpretable, biological information. A reduced scale based on carbohydrate data was also tested. The ρ-scales offer an interface between different areas of peat research. Strategies are outlined for the selection of a subset of chemical measurements among the variables used for characterization. A multivariate strategy based on these ideas is discussed.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/cem.1180060105
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    Masthead (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992) 
    Details
    ISSN: 0886-9383
    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/cem.1180060401
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    Which principal components to utilize for principal component regression (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 217-225 
    Details
    ISSN: 0886-9383
    Keywords: Principal component regression ; Calibration ; Optimality ; Principal component selection ; Quantitative structure-activity relationship ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Principal components (PCs) for principal component regression (PCR) have historically been selected from the top down for a reliable predictive model. That is, the PCs are arranged in a list starting with the most informative (PC associated with the largest singular value) and proceeding to the least informative (PC associated with the smallest singular value). PCs are then chosen starting at the top of this list. This paper discusses an alternative procedure of treating PC selection as an optimization problem. Specifically, without any regard to the ordering, the optimal subset of PCs for an acceptable predictive model is desired. Five data sets are analyzed using the conventional and alternative approaches. Two data sets are spectroscopic in nature, two data sets deal with quantitative structure-activity relationships (QSARs) and one data set is concerned with modeling. All five data sets confirm that selection of a subset without consideration to order secures the best results with PCR. One data set is also compared using partial least squares 1.
    Additional Material: 7 Tab.
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    Diary (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. i 
    Details
    ISSN: 0886-9383
    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/cem.1180060502
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    Weighted analysis of principal components: Two approximations to statistical weightsPart of the Master of Science Thesis by D.P. (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 257-266 
    Details
    ISSN: 0886-9383
    Keywords: Principal factor analysis ; Factor analysis ; Eigenvalue analysis ; Multivariate analysis ; Weighted factor analysis ; Procrustean analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two approximate methods for weighted principal components analysis (WPCA) were devised and tested in numerical experiments using either empirical variances (obtained from replicated data) or assumed variances (derived from unreplicated data). In the first (‘spherical’) approximation each data vector was assigned a weight proportional to the geometrical mean of its variances in all dimensions. The arithmetical mean of variances was used instead in the other approximation. Both the numerical experiments with artificial data containing random errors of various kinds (constant, proportional, constant plus proportional, Poisson) and the analysis of two sets of Raman spectra clearly indicated the necessity of introducing statistical weights. The spherical approximation was found to be slightly better than the arithmetical one. The application of statistical weighting was found to improve the performance of PCA in estimation problems.
    Additional Material: 3 Ill.
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    Artificial intelligence in chemistry: Structure elucidation and simulation of organic reactions, Zdzislaw Hippe, Elsevier Science Publishers, Amsterdam, 1991, ISBN 0-444-98746-0 (Vol. 73), 278 pp., Price 240 f1 (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 286-287 
    Details
    ISSN: 0886-9383
    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/cem.1180060509
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    Predictive ability of regression models. Part I: Standard deviation of prediction errors (SDEP)Presented in part at the Euchem Conference held in Trieste, 1988, and at the Symposium on Chemometrics held in Holmsund, 1989. (1992)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 335-346 
    Details
    ISSN: 0886-9383
    Keywords: Predictive ability ; Regression ; PLS ; SDEP ; Cross-validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The standard deviation of prediction errors (SDEP) is used to evaluate and compare the predictive ability of some regression models, namely MLR, ACE and linear and non-linear PLS, the last being the best one. The parameter is determined by a cross-validation approach as an average of several runs obtained on forming groups in a random way. The variation in SDEP with the number of latent variables in PLS is also discussed.
    Additional Material: 3 Ill.
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    Chromatographic determination of low levels of chlorine in air (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 840-842 
    Details
    ISSN: 0935-6304
    Keywords: UV detection ; Fluorescence detection ; FID ; Mass spectrometry ; Air pollution ; Chlorine ; 1-Chloro-2-naphthol ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jhrc.1240151214
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    Determination of polar analytes in aqueous matrices by purge and trap (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 10-16 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Purge and Trap ; Flavors ; Wine ; Polar analytes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (not readable) fully autimated purge and trap system has been developed for (not readable) detemination of volatile wine components. The proposed system consists of sampler, a purge and trap instrument, and a GC, (not readable) steps, from the uptake of the infiltrated wine from the sampler (not readable) to the printout of the intergrated chromatograms, proceed(not readable), Typical problems occurring when analyzing polar analytes by the classical purse and trap approach have been specifically addressed. The system has been desiggned to handle such difficult (not readable) analytes. Efforts have been made to improve the reproducibility and the carry-over of these analytes. The measures adopted include: thorough rinsing and subsequent conditioning of the P + T parger; elimination of matrix effects by dilution and high salt (not readable); tight specification of purge relevant parameters; split-inter-(not readable) to improve GC retention time reproducibility.
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    Modified capillary GC/MS system enabling dynamic headspace sampling with on-line cryofocusing and cold on-column injection of liquid samples (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 24-28 
    Details
    ISSN: 0935-6304
    Keywords: GC-MS ; Headspace sampling ; On-column injection ; No column replacing ; Reversed carrier gas flow ; Honey aroma compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The paper describes a capillary GC/MS hardware arrangement allowong either:(a)on-line injection of sample of gases and vapors coming from dynamic headspace or purg & trap samplers and their subsequent cryofocusing/thermal desorption prior to the analytical capillary column (first column):(b)direct injection of liquid samples through a cold on-column injector into a second analytical column (counted in series with the first).Chromatographic profiles of acacia honey aromas provide condirmation of the suitability of this system.
    Additional Material: 4 Ill.
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    Micellar electrokinetic capillary chromatography of algal toxins (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 34-38 
    Details
    ISSN: 0935-6304
    Keywords: Micellar electrokinetic capillary chromatography, MECC ; Algal toxins ; Microcystin LR, YR, RR ; Nodularin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recent methods employed for the analysis of algal toxins have focused on high performance liquid chromatography. However these methods suffer from poor resolution, poor efficiency, and long analysis times. This study involves the investigation of a number of toxins including nodularin, microcystin LR, YR, and RR which are cyclic peptides produced by strains of blue-green algae. The electroseparation mode was micellar electrokinetic capillary chromatography (MECC) using a borate buffer containing sodium dodecyl sulfate (SDS) as the surgactant of choice. The method was optimized with standard toxin compounds and employed for the screening opf toxins in supercritical fluid extracts (SFE) of freeze-thawed algal scum samples.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200107
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    Comparison of on-column and splitless injection in capillary gas chromatography coupled with atomic emission detection (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 47-49 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Atomic emission detection ; On-column injection ; Splitless injection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200110
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    New stationary phases of conjugated π-electron systems for HPLC - characterization of structure and dynamics by solid state NMR spectroscopy (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 39-45 
    Details
    ISSN: 0935-6304
    Keywords: Solud-state NMR spectroscopy ; 1H MAS-only technique ; New stationary phases ; π-π interactions ; Separation of PAH's ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four new stationary phases for HPLC were prepared by modifying silica gel with a trifrnctional aminoalkyl silane. A conjugated π-electron system was linked to the amino group either directly or with a carboxylic anhydride as a spacer in between. Characterization and dynamic measurements of the new stationary phases were performed by solid state NMR spectroscopy. The results of the 29si and 13C CP/MAS techniques were compared with the recently developed 1H MAS-only technique. Despite strong homonuclear dipole-dipole interactions it was possible to obtain well resolved 1H MAS spectra of those stationaru phases with a high degree of crosslinking. Limited mobility of the aromatic ligand fragments is common for all examined stationaryu phases.The chromatographic properties of the new phases were tested by their ability tio sepatate a mixture of eight PAHS. It could be shown that the π-π interaction mechanism is responsible for the separation of the eight PAHs, because the elution order of the PAHs did not changem despite the use of both a nonpolar mobile phase (n-heptane) and a polar mobile phase (methanol/ water mixture).
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    Masthead (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997) 
    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.1240200201
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    Determination of artemisinin and artemisinic acid by capillary and packed supercritical fluid chromatography (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 62-66 
    Details
    ISSN: 0935-6304
    Keywords: Artemisinin ; Artemisinic acid ; Capillary supercritical fluid chromatography ; Packed supercritical fluid chromatography ; Evaporative light scattering detector ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Artemisinin (an antimalarial compound) and its bioprecursor artemisinic acid, present in the plant Atemisia annua L., were analyzed by supercritical fluid chromatography (SFS) using capillary and packed columns, coupled respectively with a flame ionization detector (FID) and an evaporative light scattering detector (ELSD). Both methods were optimized and validated with columns of different polarity in order to separate artemisinin and artemisinic acid. Analytical results were comparable, but the paced SFC-ELSD method was faster. Indeed, artemisinin and artemisinic acid were separated with an aminopropyl silica column in less than 8 minutes instead of about 25 minutes by capillary SFS. Contrary to conventional gas and liquid chromatography coupled to an UV-visible detector, SFS methods determined both compounds directly, without degradation and/or derivatization in the concentration range expected in the plant material. Results obtained on plant extracts by capillary SFS-FID and packed SFS-ELSD were confirmed by GC-MS.
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    Rapid analysis of unsaturated acidic xylooligosaccharides from kraft pulps using capillary zone electrophoresis (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 72-76 
    Details
    ISSN: 0935-6304
    Keywords: Capillary zone electrophoresis ; Alkaline borate buffer ; UV detection ; Unsaturated acidic xylooligosaccharides ; Alditol derivatives ; 4-Deoxy-L-threo-hex-4-enopyranosyluronic acid ; Hexenuronic acid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several acidic xylooligosaccharides containing unsaturated “hexenuronic acid” units, i.e. 4-deoxy-L-threo-hex-4-enopyranosy-lurinic acid (4-ΔU) units, were separated as their alditol derivatives by capillary zone electrophoriesis in 438 mM borate buffer (pH 10.3) and were detected selectively at the μM level on-column UV detection at 232 nm. These acidic oligosaccharides were obtained from birch and pine kraft pulps on enzymatic hydrolysis with endoxylanases and subsequent treatment with other Trichoderma reesei enzymes. Under the conditions empolyed, acidic 4-ΔU-containing xylooligosaccharides with a molecular size renging from trisaccharides up to nonasaccharides could be separated. Oligosaccharides with higher molecular mass were detected first. Two 4-ΔU-xylotetraose isomers, with the 4-ΔU-group linked to different xylose units in the iligosaccharide backbone, could be resolved from each other with a resolution of about 1. By using a disaccharide (4-ΔU α-(1 → 4) linked to N-acetyl glucosamine) as a model compound the minimum detectable concentration was determined as 10 μM.
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    Characterization and monitoring of amitraz degradation products in honey (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 81-84 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography-atomic emission detection (GC-AED) ; Gas Chromatography-mass spectrometry(GC-MS) ; Amitraz residues ; Hoeny ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary gas chromatography in combination with atomic emission and electron impact-chemical ionizaion mass spectrometry detectors have been used to detect amitraz degradation products in honey storage, characterize their structure, and evaluate their occurrence over a 100 day peroid. To this end, honey samples were extracted with an 8:2 v/v n-hexane/acetone mixture. Amitraz was found to be rapidly decomposed into five related compounds, of which N-(2,4-dimethylphenyl)formamide was the most abundant and persistent.
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    Whey proteins eluted reversed phase gradients (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 29-33 
    Details
    ISSN: 0935-6304
    Keywords: LSS model ; Whey proteins ; RP-HPLC of proteins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behavior of bovine whey proteins in Reversed-Phase High Performance Liquid Chromatography (RP-HPLC) systems has been investigated. The Linear Solvent Strength (LSS) model has been applied to the separation of these proteins studying how their retention time and band broadening change when different gradient parameters are modified. From our results it is deduced that the LSS model describes the behaviour of the whey proteins in RP-HPLC. Also, it seems that ts (the retention time for non-retained solutes) depends on the size of these proteins. The good fit observed between experimental data and the equations deduced from the LSS model allows the prediction of a gradient shape that permits a rapid analysis of the above mentioned proteins.
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    URL: http://dx.doi.org/10.1002/jhrc.1240200106
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    Gas chromatographic separation of chiral organochlorines on modified cyclodextrin phases and results of marine biota samples (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 85-93 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Modified cyclodextrin phases ; Chiral organochlorines ; Biological samples ; Enantiomeric ratios ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four chiral stationary phases containing modified cyclodextrines diluted in or chemically bonded to a non-chiral phase were used to resolve chiral organochlorine compounds such as α-hexachlorocyclohexane (α-HCH), perdeuterated α-HCH (α-PDHCH), β-and γ-pentachlorocyclohexene (PCCH), oxychlordane, cis-and trans-chlor- dane, cis- and trans-heptachlorepoxide, PCB 95, PCB 132, PCB 149, and Chiral tozaphenes.The elution order was determined by analyzing standards with known enantiomeric excesses.Furthermore, an internal standard was used to even out slight variations in the ratio of peak hights of enantiomers which were determined from injection to injection.None of the chiral stationary phases resolved all chiral organochlorine compounds. However, the β-TBDM(35% heptakis (6-O-t-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin in OV 1701) column allowed the separation of all compounds under investigation except for PCB 95 and chiral toxaphenes.Emphasis was placed on the separation of as many as possible enantiomers on a chiral phase by application of one temperature program and with respect to unambiguous quantitation of biological samples such as bludder and liver of marine and terrestrial mammals.
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    Troubleshooting in the separation sciences (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 122-122 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/jhrc.1240200214
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    Chromatography calendar (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 123-124 
    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.1240200215
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    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.
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    The characterization and quantitation of sulfur-containing compounds in (heavy) middle distillates by LC-GC-FID-SCD (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 131-137 
    Details
    ISSN: 0935-6304
    Keywords: LC-GC hyphenation ; Sulfur chemlluminescence detector ; Organo-sulfur compounds ; Hydrodesulfurizalion ; Middle distillates ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modified sulfur chemiluniinescence detector (SCO) has been interfaced to a HPLC-HRGC hyphenated system. This combination enables the full characterization and quantitation of the sulfur containing compounds in (heavy) middle distillate oil fractions (boiling range 150-450°C). The system is suited to identify and determine the various groups of orgaiio-sulfur structures such as: thiols + sulfides + thiophencs, benzothiophenes, dibenzothiophenes and benzo-naphthothiophenes. Within these groups a separation according to boiling point is accomplished. Therefore it allows the separation, identification and quantitation of a number of individual species, especially those which are refractory to hydrodesulfu-rization (HDS), such as 3-methyl-benzothiophene, 4-methyl-dibenzothiophene and -J,6-dimethyl-dibenzothiophene. The analysis of these groups and specific compounds is the key in understanding the kinetics of the chemistry involved in HDS. The complete instrumental set-up is fully automated by computer control. To suppress possible interferences and quenching of the sulfur response of the SCL from (large amounts of) hydrocarbons, it is aligned above the adapted flame ionization detector (FID) of the GC. This renders a sensitivity of the SCO for sulfur of 2 pg. s-1, which corresponds to a minimum detectable level for individual sulfur species in oil fractions for the complete system of 1 ppm (mg. kg-1) sulfur. Its linear dynamic range exceeds 105, which means that also untreated, high sulfur containing feedstocks can be analyzed directly. The selectivity of sulfur to carbon of the modified SCO exceeds 106. A number of HDS feedstocks and desulfurized products of different desulfurization levels have been analyzed with the system. From the analysis results the behavior of the refractory compounds in HDS can now be followed closely.
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    Standard equivalent chain length values of monoenic and polyenic (methylene interrupted) fatty acids (1997)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 143-158 
    Details
    ISSN: 0935-6304
    Keywords: High resolution gas chromatography ; Column reproducibility ; Equivalent chain length values ; Fatty acid methyl ester analysis ; Capillary columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equivalent chain length (ECL) values of the methyl esters of 83 defined fatty acids (FAs) have been determined by gas chromatog-raphy (GC) on three fused silica DB-WAX and three DB-1 columns. ECL values of further 46 FAs were calculated by different methods. Conditions of chromatography, methods of ECL values calculation and differences between ECL values on individual columns and between trans- and cis-isomers of corresponding FAs are also discussed.
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    Composition and Microstructure Determination of the Syndiotactic Copolymer of para-Methylstyrene and Styrene by Pyrolysis Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 11-16 
    Details
    ISSN: 0935-6304
    Keywords: Pyrolysis gas chromatography ; microstructure determination ; syndiotactic copolymers ; styrenes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The composition and microstructure of syndiotactic para-methylstyrene/styrene copolymer was determined by a pyrolysis gas chromatography (Py-GC) method. This method uses the styrene and para-methylstyrene monomer peak intensities to determine the styrene and para-methylstyrene composition in the copolymer. The number average sequence length of styrene was calculated by using the triad peak intensities. Because of the low concentration of para-methylstyrene in the copolymer, the number average sequence length of para-methylstyrene was determined with formulas that incorporate the copolymer composition and the number average sequence length of styrene. The distribution of para-methylstyrene defined by the terms “percent of single units” and “percent of desired distribution” was calculated by the number average sequence of para-methylstyrene. This method has been tested with copolymers containing up to 24 mole% of para-methylstyrene. The composition results from Py-GC of para-methylstyrene and styrene copolymers used in this study were in excellent agreement with 1H-NMR results.
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    Superior ECD Performance through Design and Application (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 24-28 
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    ISSN: 0935-6304
    Keywords: Gas chromatography ; ECD ; Micro-ECD ; GC detector ; organochlorine pesticides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new ECD, the HP 6890 Series Micro-ECD, was designed to address inherent deficiencies in classical electron capture detectors (ECD), especially with respect to sensitivity, linearity, dynamic range, and ruggedness. Several novel technologies were incorporated in the totally new design and were refined through practical testing and user feedback. Validation of the micro-ECD performance was accomplished through side-by-side testing of the Micro-ECD with previous ECDs following US EPA Contract Laboratory Program methods for pesticides and PCBs. In addition, extensive interviews were conducted with early users of the Micro-ECD who also had experience with other designs running a variety of ECD methods. The design and resulting performance improvements are described.
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    Experimentation with Chiral CE: The Application of Two Chiral Selectors and Partial Filling with Chiral Selector (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 33-38 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; chiral separation ; negatively charged chiral selectors ; capillary filling methods ; dual systems ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Data on the use of two chiral selectors, namely 18-crown-6 tetracarboxylic acid and a negatively charged cyclodextrin derivative (sulfated-β-cyclodextrin or carboxymethyl-β-cyclodextrin), in the same background electrolyte are presented. The use of such dual systems has a considerable influence on the resolution, as illustrated for the separation of tryptophan derivatives. Reduction of the consumption of chiral selector without significant loss in resolution was obtained by only partly filling the capillary and applying a run buffer without selector. This is illustrated for the chiral separation of tryptophan hydroxamate and the diastereomeric and enantiomeric separation of the dipeptide α/b-AspPhe-OMe.
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    Determination of Free Diterpenes in Green and Roasted Coffees (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 43-46 
    Details
    ISSN: 0935-6304
    Keywords: Green and roasted coffee ; diterpenes ; cafestol ; kahweol ; 16-O-methylcafestol ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The three coffee diterpenes cafestol, kahweol, and 16-O-methylcafestol are mostly esterified with fatty acids. Little has been published about the diterpenes occurring in the free form. By means of gel permeation chromatography on Bio Beads S-X3, it is now possible to simultaneously analyze and quantify the small amounts of these compounds by RP-HPLC. In this way, free kahweol was first proved to be an ingredient of Robusta coffee. Various Arabica and Robusta coffees - both green and roasted - were investigated. Free diterpenes were found in green coffees in amounts below 200 mg/kg dry matter. In comparison to the respective total diterpene content determined by the same HPLC method after saponification of the coffee oil, the proportion of free diterpenes ranged from 0.7 to 3.5 %. During the roasting process, the three uncombined diterpenes behaved similarly: free 16-O-methylcafestol, cafestol as well as kahweol were degraded with increasing roasting temperature.
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    Optimization through Factorial Planning of the Use of Ethanol : Water as a Mobile Phase for Reversed Phase HPLC (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 52-54 
    Details
    ISSN: 0935-6304
    Keywords: Ethanol ; mobile phase ; factorial planning ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Levels of Organotin Compounds in Burbot (Lota Lota) from Norwegian Lakes (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 177-180 
    Details
    ISSN: 0935-6304
    Keywords: Fresh water systems ; burbot ; organotin compounds ; speciation analysis ; GC-AED ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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    RP-HPLC and GC-MS Techniques for the Quantitative Analysis of Substituted 1,2,4-Trioxanes and their Thermolysis Products in Solution (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 67-69 
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    ISSN: 0935-6304
    Keywords: RP-HPLC ; GC-MS ; trioxanes ; thermolysis products ; quantitative analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    A Robust Thermal Modulator for Comprehensive Two-Dimensional Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 3-10 
    Details
    ISSN: 0935-6304
    Keywords: Multidimensional Gas Chromatography ; orthogonal separations ; GC×GC ; comprehensive two-dimensional chromatography ; characterization of gasoline ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---In comprehensive two-dimensional gas chromatography (GC×GC), two capillary columns are connected in series through an interface known as a “thermal modulator”. This device transforms effluent from the first capillary column into a series of sharp injection-like chemical pulses suitable for high-speed chromatography on the second column. Dramatic increases in the resolving power, sensitivity, and speed of the gas chromatograph result. This paper describes the development of a robust and reliable thermal modulator for GC×GC.
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    Effect of Mobile Phase Components on the Separation of Polypeptides Using Carbon Dioxide-Based Mobile Phases (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 74-78 
    Details
    ISSN: 0935-6304
    Keywords: Polypeptides ; subcritical fluid chromatography ; supercritical fluid chromatography ; carbon dioxide ; additives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The effect of mobile phase modifier and additive on the chromatographic properties of various small polypeptides was explored under subcritical conditions. A polymeric column was used to separate various enkephalin analogs, bradykinin, and oxytocin using a carbon dioxide-based mobile phase with either an ethanol or a 2-methoxyethanol modifier. The role of the modifier was found to be secondary to that of the mobile phase additive. As progressively stronger acidic mobile phase additives were used, the peak profiles of the various polypeptides improved and retention decreased. Heptadecafluorooctanesulfonic acid was found to be the most useful additive for these types of solutes under near-critical conditions, while the potassium salt of heptadecafluorooctanesulfonic acid failed to elute any of the polypeptides. At low temperatures, pressure gradients with a carbon dioxide/ethanol/heptadecafluorooctanesulfonic acid ternary mobile phase produced reasonably good peak profiles with the polymeric column.
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    γ(δ)-Thionolactones - Enantioselective Capillary GC and Sensory Characteristics of Enantiomers (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 89-92 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin ; heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin ; γ(δ)-thionolactones ; olfactometry ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The even numbered γ(δ)-thionolactones (C6-C12) were investigated, using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)- and heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as chiral stationary phases in capillary gas chromatography. The odor characteristics of γ(δ)-thionolactone enantiomers were investigated by enantioselective gas chromatography/olfactometry.
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    Programmable Temperature Vaporizer (PTV) Applied to the Triglyceride Analysis of Milk Fat (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 93-96 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; PTV and on-column injectors ; milk fat triglycerides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The PTV (Programmable Temperature Vaporizer) is a split/splitless injector which allows the sample to be introduced at a relatively low temperature, thus affording accurate and reproducible sampling. After injection the PTV is rapidly heated to transfer the vaporized components into the capillary column. This type of injector has proved to be an efficient tool for the evaluation of fatty acids, essential oils, and pesticides in food analysis. In this work the suitability of PTV for the analysis of milk fat purity by the Official EU method was evaluated. This method is based on the gas chromatographic determination of triglycerides only according to their total number of carbon atoms followed by the application of formulae deriving from multiple linear regressions. The analysis is currently carried out with a packed column or a short capillary column and an on-column injection system. Several samples of pure milk fat and mixtures of milk fat with foreign fat were analyzed with the same capillary column and by using both PTV and on-column injection systems. The results show that the gas chromatographic profile obtained by PTV is comparable with that obtained by the on-column injector, while repeatability and reproducibility data meet the requirements indicated in the Official Method. Therefore, this study demonstrates that it is possible to use the PTV instead of the on-column injector to determine the purity of milk fat with this method.
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    Study of the Linear Range in HPLC Analyses with UV Detection: Methodology and Experimental Application to the Influence of the Analyte UV Spectrum (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 217-221 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; UV detection ; linear range ; method validation ; Beer-Lambert law ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Determination of the linear range is one of the main concerns in validation of an HPLC analysis method. It is particularly important since single point calibration will be then used routinely. We proposed an iterative methodology to handle this problem. The idea was, at each step, to test statistically whether the following point belonged to the same regression line. The methodology was then used to evaluate quantitatively the effect on linear range of a shift in detection wavelength or of the detector bandwidth. Although experimental results were globally in accordance with spectroscopic theory, magnitudes observed were rather large. So the linear range could vary by a factor of over 2 with changes in conditions that remained within the range of current practical values. Changes in detection wavelength were limited to about fifteen nm around λmax and the detector used was considered to be representative of modern high-performance UV detectors. The question of how to take consequences in method validation into account was raised. The solution proposed recommended that the validation was undertaken in conditions as close as possible to those where the method would be conducted routinely. This means with the same instrumentation and on the product of interest for analyses.
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    Equilibrium-Sorptive Enrichment: A Novel Technique for Trace Analysis in Air (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 231-234 
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    ISSN: 0935-6304
    Keywords: Trace analysis ; air samples ; BTX ; equilibrium-sorptive enrichment ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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    Theoretical Design Considerations for Multi-capillary Columns in Fast Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 119-122 
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    ISSN: 0935-6304
    Keywords: Fast gas chromatography ; multi-capillary column ; band broadening ; simulation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    GC-MS Determination of Kava-Pyrones in Alpinia zerumbet Leaves (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 129-130 
    Details
    ISSN: 0935-6304
    Keywords: GC-MS ; kava pyrones ; Alpinia zerumbet ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    On-Line Coupling of Separation Techniques to NMR (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 135-143 
    Details
    ISSN: 0935-6304
    Keywords: Chromatographic separation techniques ; High Performance Liquid Chromatography (HPLC) ; Gel Permeation Chromatography (GPC) ; Supercritical Fluid Chromatography (SFC) ; Capillary HPLC ; Nuclear Magnetic Resonance (NMR) spectroscopy ; hyphenation of chromatography with NMR spectroscopy ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The hyphenation of chromatographic separation techniques with NMR spectroscopy is one of the most powerful and time-saving methods for the separation and structural elucidation of unknown compounds and molecular compositions of mixtures. Most of the routinely used NMR flow-cells have detection volumes between 40-180 μL for conventional separations with analytical columns, and the newest designs employ detection volumes in the order of 200 nL for capillary separations. The low flow rates used in capillary chromatography permit the use of deuterated solvents. Unequivocal structural assignment of unknown chromatographic peaks is possible by two-dimensional stopped-flow capillary HPLC-NMR experiments.
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    Enhanced Resolution of Conjugated Linoleic Acid Isomers by Tandem-Column Silver-Ion High Performance Liquid Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 144-148 
    Details
    ISSN: 0935-6304
    Keywords: Conjugated linoleic acid (CLA) ; silver-ion high performance liquid chromatography (Ag+-HPLC) ; cheese ; analysis ; silver-ion chromatography ; tandem-column Ag+-HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A commercial mixture of conjugated linoleic acid (CLA) isomers, reportedly consisting of six components, was recently resolved into 12 peaks attributed to CLA isomers using silver-ion high performance liquid chromatography (Ag+-HPLC). In this study, the coupling of two analytical silver-ion high performance liquid chromatography columns (tandem-column Ag+-HPLC) in series led to the enhanced resolution of CLA isomers. Many CLA isomers were baseline resolved and the pair 18 : 2 8,10 c/t and 18 : 2 7,9 c/t found in cheese products, was resolved for the first time. In this work, a similar commercial CLA mixture was separated into 16 peaks, while CLA isomers from cheese also gave rise to 16 peaks. As expected, the CLA isomers were separated into three geometric groups in the order trans,trans, cis/trans, and cis,cis. Semi-preparative Ag+-HPLC, followed by gas chromatography-mass spectroscopy of the dimethyloxazoline derivatives, was used to confirm the identity of the newly resolved positional CLA isomers. The double bond configuration of CLA isomers was established by gas chromatography-Fourier transform infrared spectroscopy. Two minor t,t CLA isomers found in cheese, presumably 18 : 2 t6t8 and 18 : 2 t13t15, were also separated. The CLA isomeric composition of 16 commercial cheese products was determined.
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    The Importance of Solvent Venting to Reduce Memory Effects with On-Line LC-GC-AED (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 159-163 
    Details
    ISSN: 0935-6304
    Keywords: Multi-dimensional chromatography ; LC-GC ; AED ; memory effects ; fossil fuel ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Conventional operation of the GC Atomic Emission Detector (AED) system involves backflushing of the microwave induced plasma (MIP) during the elution of small volumes of solvent from the GC column. When performing multi-dimensional, on-line LC-GC-AED, significantly larger solvent volumes are introduced into the system and must subsequently be removed. Thus solvent venting procedures are required and the backflushing of the plasma must be extended to facilitate solvent but not solute removal. This study demonstrates the significance of memory effects imparted upon the MIP of the AED if solvent venting is incomplete. Comparison of conventional GC-AED and multi-dimensional LC-GC-AED is made with respect to a fossil fuel sample.
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  • 82
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    Multiresidue Analysis of Phenylurea Herbicides in Environmental and Drinking Water by Capillary Electrophoresis (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 171-176 
    Details
    ISSN: 0935-6304
    Keywords: Micellar electrokinetic chromatography (MEKC) ; solid phase extraction (SPE) ; phenylurea(s) ; herbicide(s) ; monuron ; linuron ; diuron ; isoproturon ; monolinuron ; drinking water ; environmental water ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The present paper describes the application of capillary electrophoresis in the micellar mode to the separation and quantitative determination of five phenylurea herbicides, viz. monuron, linuron, diuron, isoproturon, and monolinuron, in water samples. Using uncoated fused silica capillary and phosphate-borate buffer (pH 7.0) containing SDS, the five pesticides are resolved in less than 15 min and quantitatively determined by an ultraviolet detector at 244 nm. Method optimization and validation parameters are presented. Good linearity and repeatability were observed for all the compounds studied (correlation coefficients 0.999). The feasibility of the method developed was tested by simultaneous determination of these herbicides in environmental and drinking water samples at the minimum residue levels (MRLs) (0.1 μg/L) after solid-phase extraction (SPE) preconcentration procedure.
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    Solid Phase Microextraction and GC-MIP-AED for the Speciation Analysis of Organomercury Compounds (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 181-182 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; microwave induced emission spectrometry ; speciation ; mercury ; SPME, headspace SPME ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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    At-Line Solid-Phase Extraction Coupled to Capillary Electrophoresis: Determination of Amphoteric Compounds in Biological Samples (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 183-187 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; interfacing ; sample treatment ; serum ; solid-phase extraction ; sulfonamides ; urine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 85
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    Analysis of Mixtures of Fatty Acid Esters by Chromarod Chromatography/Flame Ionization Detection (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 191-194 
    Details
    ISSN: 0935-6304
    Keywords: TLC/FID ; simple and double migration ; triangle of solvent selectivity ; lipochemical media ; fatty acid esters ; esterification ; transesterification ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 3 Ill.
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  • 86
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    Determination of 1,4-Dioxane in Toluene by Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 201-204 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; flame ionization detection ; solvent effects ; aqueous injection ; toluene analysis ; dioxane ; sample preparation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A gas chromatographic method is presented for determining from 1 to 100 μg/mL of 1,4-dioxane in toluene with purities ranging from commercial to high-purity grades. This method relies on extracting 1,4-dioxane from toluene into water. The water extract is analyzed for 1,4-dioxane content by gas chromatography/flame ionization detection and a capillary column coated with a bonded polyethylene glycol stationary phase. Splitless injection is used to achieve a 1 μg/mL detection limit. Purging extracts with nitrogen after an initial analysis is suggested as an extract clean-up procedure and as a means to confirm the identification of 1,4-dioxane. However, for absolute identification of dioxane, gas chromatography/mass spectroscopy should be considered.
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    Flow Rate and Velocity of Ideal Gas in a Capillary Column with Uniform Permeability (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 213-216 
    Details
    ISSN: 0935-6304
    Keywords: Average velocity ; characteristic parameters ; flow rate ; high pressure drop ; low pressure drop ; outlet velocity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: When the column pressure drop is high, the average velocity of a carrier gas is proportional to the square root of the outlet velocity and the flow rate. Characteristic velocity, flow rate and pressure - the boundary conditions between low and high pressure drop regions - are introduced. Previously derived equations for average velocity vs. outlet velocity were modified to include the flow rate and to become more suitable for the separate studies of the low and high pressure drop regions.
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    Determination of Green and Black Tea Composition by Capillary Electrophoresis (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 225-230 
    Details
    ISSN: 0935-6304
    Keywords: Green tea ; black tea ; composition ; stability ; capillary electrophoresis ; MEKC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 6 Ill.
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    High Speed Cryogenic Modulation - A Technology Enabling Comprehensive Multidimensional Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 235-238 
    Details
    ISSN: 0935-6304
    Keywords: Cryogenic modulation ; LMCS ; GC×GC ; multidimensional GC ; comprehensive gas chromatography ; petroleum analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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    Heptakis(6-O-ethyl-2,3-O-pentyl)-β-cyclodextrin: A New Chiral Stationary Phases for Capillary GC (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 242-244 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; 6-O-ethyl-2,3-O-pentyl-β-cyclodextrin ; essential oils ; carboxylic acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 3 Ill.
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    Determination of Amitraz in Cattle Dipping Baths by High-Performance Liquid Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 247-249 
    Details
    ISSN: 0935-6304
    Keywords: High performance liquid chromatography-ultraviolet detection (HPLC-UV) ; Amitraz ; cattle dipping bath ; pesticide ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 92
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    On-Line Coupled Liquid Chromatography - Gas Chromatography in the Analysis of Process Samples (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 261-264 
    Details
    ISSN: 0935-6304
    Keywords: On-line coupled LC-GC ; normal phase liquid chromatography ; process samples ; oxygenated compounds ; partially concurrent solvent evaporation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Normal phase liquid chromatography-gas chromatography was used with on-column interfacing and partially concurrent solvent evaporation in the analysis of process samples. Samples were taken from reaction mixtures, where the solvent was toluene. The analytes were oxygenated compounds: methyl isobutyrate, methyl methacrylate, methyl α-formyl isobutyrate, and methyl β-formyl isobutyrate. The analytes were transferred from LC to GC using back-flush with a solvent mixture of pentane and diethyl ether. Linearity, repeatability, and transfer efficiency were determined for the method. The method was applied in the determination of the analytes of two different process samples. The results were in good agreement with results obtained by the gas chromatographic method currently in use for the analysis of the process samples.
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    Determination of the Critical Micelle Concentration of Cationic Surfactants by Capillary Electrophoresis (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 265-270 
    Details
    ISSN: 0935-6304
    Keywords: Critical micelle concentration ; cationic surfactant ; capillary electrophoresis ; tetradecyltrimethylammonium bromide ; dodecyltrimethylammonium bromide ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The determination of the critical micelle concentration (CMC) of cationic surfactants by capillary electrophoresis was demonstrated. In this study, tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DoTAB) were selected as cationic surfactants and propazine was chosen as test solute. In the evolution of the effective electrophoretic mobility of propazine as a function of surfactant concentration, a dramatic change in slope at a particular concentration is a good indication of the CMC of this surfactant. The CMC values determined experimentally were further confirmed by a curve-fitting approach. Simulation of the electrophoretic mobility curves as a function of surfactant concentration in both micellar electrokinetic chromatography and capillary zone electrophoresis using cationic surfactants as an electrolyte modifier was performed for propazine, and the intersection of these two mobility curves allowed us to precisely predict the CMC of the surfactant. The CMC values determined for TTAB and DoTAB are 1.6 ± 0.1 and 11.0 ± 0.1 mM, respectively, in the case of an electrolytic solution consisting of 70 mM phosphate buffer at pH 6.0. Moreover, the applicability of the electroosmotic mobility as a parameter for the determination of the CMC was examined.
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    A Unified Sample Preparation System for Extraction of Various Analyte/Matrix Combinations (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 271-275 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical fluid extraction ; enhanced solvent extraction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A supercritical fluid extraction/enhanced solvent extraction system (SFE/ESE) was used to remove polar and non-polar analytes from various matrices. Extraction of environmental pollutants from soil, additives from low density polyethylene, sulfa drugs from animal tissue, and drug from tablet was performed using both SFE and ESE. Results showed that a single instrumental system can be used to perform both ESE with organic solvents and SFE with carbon dioxide-based fluids. Each method has its own unique advantages and applications. The ability to carry out both solvent extraction and supercritical fluid extraction with one system has obvious economical advantages.
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    An Improved Interface for Coupling Solid-Phase Microextraction (SPME) to High Performance Liquid Chromatography (HPLC) Applied to the Analysis of Explosives (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 279-282 
    Details
    ISSN: 0935-6304
    Keywords: Solid phase microextraction (SPME) ; SPME/HPLC interface ; C-8 refocusing unit ; explosives analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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    Analysis of the Naturally Occurring Pesticide Rotenone by Capillary Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 294-296 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; capillary ; fused silica ; rotenone ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
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    Isolation of Polychlorodibenzo-p-dioxins and Polychlorobiphenyls upon Deproteinization of a Serum Sample by HPLC with Restricted-Access Reversed-Phase Packing Materials (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 287-293 
    Details
    ISSN: 0935-6304
    Keywords: Deproteinization ; polychlorobiphenyls ; polychlorodibenzo-p-dioxins ; restricted-access reversed-phase packings ; sample preparation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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    Determination of Trichothecene Toxin (T2 Mycotoxin) in Aqueous Sample with Solid Phase Microextraction Technique Followed by Gas Chromatography with Flame Ionization Detection (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 424-426 
    Details
    ISSN: 0935-6304
    Keywords: Mycotoxin ; T2 ; solid phase microextraction ; GC/FID ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 4 Ill.
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    Preparation of On-Column Frits in Packed Fused Silica Capillaries by Sol-Gel Technology (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 438-442 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrochromatography ; micro-HPLC ; preparation of on-column frits ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Existing methods for preparing frits in packed fused silica capillaries as used for electrochromatography and micro HPLC are not applicable to all silica based packing materials and involve a high thermal stress for both the stationary phase and the fused silica tubing including the polyimide coating. A new procedure for the production of such on-column frits under mild conditions by a sol-gel type reaction of polydimethoxysiloxane (PDMOS) is described in this paper. Reaction conditions were established for optimum mechanical stability and high permeability of the frits. Frits produced in this manner showed no noticeable effect on the overall efficiency.
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    Application of Temperature and Applied Voltage Programming in Micellar Electrokinetic Capillary Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 443-448 
    Details
    ISSN: 0935-6304
    Keywords: Micellar electrokinetic capillary chromatography ; temperature programming ; applied voltage programming ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Temperature and voltage programming modes were utilized to optimize selectivity and increase the eluting rate of strongly retained compounds in micellar electrokinetic chromatography. Separations obtained by applying temperature, voltage, and a simultaneous combination of temperature and voltage gradient in micellar electrokinetic capillary chromatography were compared with separations performed under isothermal and constant voltage conditions. A complete separation of all the constituents of the test mixture was only achieved in the temperature programming run and in a combination of temperature and voltage programming modes. Simultaneous variations of column temperature and applied voltage during a separation run, yielded a 30% reduction in the total analysis time when compared to a temperature gradient alone. Temperature programming and voltage programming modes may be the gradient methods of choice because of the considerable technical difficulties involved in performing linear solvent gradient elution in micellar electrokinetic chromatography.
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