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  • 1
    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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    Paper (German National Licenses)
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  • 2
    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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    Paper (German National Licenses)
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  • 3
    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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    Paper (German National Licenses)
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  • 4
    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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  • 5
    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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