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  • 1
    Electronic Resource
    Electronic Resource
    Application of Pattern Recognition Methods for the investigation of chemical homogeneity of solids (1985)
    Springer
    Microchimica acta 85 (1985), S. 219-226 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Zwei Pattern-Recognition-Methoden, die mehrdimensionale Varianzund Diskriminanzanalyse (MVDA) und die Punktdichteanalyse (PDA) wurden zur Homogenitätscharakterisierung von Festkörpern eingesetzt. Die Anwendung auf Proben mit unterschiedlichem Charakter der Konzentrationsverteilung zeigt, daß sich diese Methoden vorteilhaft zur Homogenitätscharakterisierung eignen und weitgehend unabhängig von der Ortsfrequenz der Konzentrationsschwankungen sind.
    Notes: Summary Two Pattern Recognition Methods, the Multivariate Variance and Discriminance Analysis (MVDA) and the Point Density Analysis (PDA), were applied to problems of chemical homogeneity of solid samples. The results obtained with three examples, representative for different types of inhomogeneities, show that these methods are advantageously applicable for characterizing homogeneity independent from the local frequency of the concentration fluctuation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01198294
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  • 2
    Electronic Resource
    Electronic Resource
    Use of solid-phase microextraction-capillary-gas chromatography (SPME-CGC) for the varietal characterization of wines by means of chemometrical methods (1998)
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 784-787 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The extraction of wine aroma compounds was studied by direct-SPME (DI/SPME), headspace-SPME (HS/SPME) and multiple-headspace-extraction-SPME (MHE/SPME). The aromagrams obtained by HS/SPME-CGC were evaluated with chemometrical methods for the varietal classification of wines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050806
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Classification of wine samples by means of artificial neural networks and discrimination analytical methods (1997)
    Springer
    Fresenius' journal of analytical chemistry 359 (1997), S. 143-149 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The three-layer artificial neural network (ANN) model with back-propagation (BP) of error was used to classify wine samples in six different regions based on the measurements of trace amounts of B, V, Mn, Zn, Fe, Al, Cu, Sr, Ba, Rb, Na, P, Ca, Mg,  K using an inductively coupled plasma optical emission spectrometer (ICP-OES). The ANN architecture and parameters were optimized. The results obtained with ANN were compared with those obtained by cluster analysis, principal component analysis, the Bayes discrimination method and the Fisher discrimination method. A satisfactory prediction result (100%) by an artificial neural network using the jackknife leave-one-out procedure was obtained for the classification of wine samples containing six categories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050551
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  • 4
    Electronic Resource
    Electronic Resource
    Multivariate optimization of signal intensities in atomic emission spectroscopy using overlapping resolution maps (1992)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 342 (1992), S. 1-9 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The overlapping resolution map method (ORM) formerly developed for simultaneous peak separation in chromatography has been modified and applied to multivariate optimization in atomic spectroscopy. It has been found that the method works very well for the simultaneous optimization of a set of signal intensities of m analytes in optical emission spectroscopy (OES) as functions of p independent spectroscopy variables, e.g. measuring conditions. The method works especially well in connection with computer graphics for up to three variables because the optimization results may be directly visualized. The experimental example under study was the optimization of the current intensity of the electrical arc and the concentration of NaCl as spectrochemical addition for the simultaneous determination of Cu, Mn, Si, Cr, Fe and Mg traces in highly purified Al2O3 powder by direct solid state OES.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321680
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  • 5
    Electronic Resource
    Electronic Resource
    Chemometric investigations on the representativity of soil sampling (1992)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 342 (1992), S. 267-272 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The characterization of the heavy metal contents of a soil area is carried out by narrow screening sampling and subsequent analysis. It is possible by means of the univariate variance analysis to detect significant alterations within the tested area. The position and extent of multivariate changes of the features can be characterized more exactly with the help of multivariate statistical methods such as the combination of cluster and discriminant analytical methods or the principal component analysis. The maximum possible distance between two sampling points is determined by calculation of the autocorrelation function of the features. The number of soil samples, which is necessary for precisely determining the heavy metal contents of the investigated area, can be derived therefrom. With the help of the multivariate autocorrelation function the distance for the representative sampling of the multivariate loads by heavy metals can be described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00322167
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  • 6
    Electronic Resource
    Electronic Resource
    Multisignal calibration in optical emission spectroscopy (1993)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 346 (1993), S. 520-524 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The possibility of using more than one line for calibration in optical emission spectroscopy has been investigated. By means of principal component regression, sensitivity can be increased and part of noise can be removed. Thus, lower limits of detection can be obtained. The extent of improvement of sensitivity is considered theoretically and investigated by simulation. In the ideal case the sensitivity of the principal component regression for more than one line is calculated from the square root of the sum of squares of the sensitivities of the single lines. Practical applications in arcoptical emission spectroscopy and ICP-OES show that the theoretically expected improvements can almost be reached. The reduction in noise depends on the nature and source of noise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321235
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  • 7
    Electronic Resource
    Electronic Resource
    A review of information theory in analytical chemometrics (1990)
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 4 (1990), S. 195-216 
    Details
    ISSN: 0886-9383
    Keywords: Entropy ; Decrease of uncertainty ; Information gain ; Relevance coefficients ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Information theory makes it possible to judge and evaluate methods and results in chemical analysis. The obtained information can be expressed in different ways. One way is to define information as the decrease of uncertainity after analysis. Conditional probabilities are therefore considered when evaluating the information provided by qualitative analyses. However, the use of other information measures, such as the information gain, is often preferable. In multicomponent analysis the translation of information from signals to the amounts of the analytes has been investigated along with the relevance of individual components. Information theory can also be applied to find the optimum experimental conditions. The evaluation of the properties of analytical methods by information theory has been proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cem.1180040303
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  • 8
    Electronic Resource
    Electronic Resource
    Improvement of the Chemometric Variety Characterization of Wines by Improving the Detection Limit for Aroma Compounds (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 322-326 
    Details
    ISSN: 0935-6304
    Keywords: Solid phase microextraction (SPME) ; capillary gas chromatography ; detection limits ; wine aroma compounds ; classification of wines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Headspace-SPME followed by capillary gas chromatography/mass spectrometry was used to investigate 90 German wines originating from different grape varieties, vintages, and growing areas. Aromagrams obtained in single ion monitoring (SIM) and in the full scan detection mode (SCAN) of quadrupole mass spectrometer were compared. Detection limits, reproducibility, and linearity for some aroma relevant substances were estimated over a wide concentration range. The advantages of SIM data set (lower detection limit, better reproducibility and linearity in the smaller concentration ranges) should be reflected in more reliable results in classification of wines. To verify these expectation, classification of variety by discriminant analysis was performed with cross validation using both SIM and SCAN data sets including 19 aroma compounds, respectively.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    Multisignal calibration in spark- and ICP-OES (1994)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 350 (1994), S. 339-343 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The advantages of multivariate calibration by using more than one selective emission line for one analyte are described in comparison with univariate calibration. Principle component regression (PCR) and partial least squares regression (PLS) are compared with classical univariate linear regression of single lines. Practical applications in spark- and inductively coupled plasma optical emission spectroscopy (ICP-OES) show that the sensitivity can be increased and thus a lower limit of detection be obtained by means of these multivariate techniques. Results from the investigations concerning the problem of collinearity are also discussed. Disturbed analyte lines are included in multisignal calibration. Their influence on the results of calibration is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325602
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Systematic optimization of the analysis of wine bouquet components by solid-phase microextraction (1996)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 257-262 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Solid-phase microextraction ; Food analysis ; Wine bouquet ; Monoterpenes ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The extraction, identification, and quantification of wine aroma compounds are preliminary steps required for further investigation of wine quality, i.e. determination of the varieties of grapes used, the production process, and the origin and age of the wine. This paper deals with the optimization of solid-phase microextraction for the determination of compounds which produce wine bouquet. Optimum operating conditions have been determined to obtain high reproducibility at low cost and with low time-consumption. Several factors influencing the equilibrium of the aroma compounds between the sample and the fiber must be taken into account, including length of contact time between the two phases involved, speed of agitation of the sample, the matrix in which the process takes place, and, furthermore, the place, duration, and temperature of desorption in the injector of the chromatograph.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240190504
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    Paper (German National Licenses)
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