Informationstheorie in der Analytik

Summary The information amount characterizing multicomponent analyses is derived for the qualitative and quantitative evaluation of independent and correlated analytical signals, respectively. It must be distinguished between detection and determination of certain selected components on the one hand and the identification of unknown components on the other hand. Selectivity, relevance and redundance of instrumental analytical methods are evaluated in connection with their potential information capacity. The information performance and effectivity are specified with regard to practical analytical problem solving.

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Teil I: Fresenius Z Anal Chem (1987) 327:312     

Application of reference materials for quality assessment in neutron activation analysis-use of information theory

It is generally accepted that an analytical procedure can be regarded as an information production system yielding information on the composition of the analyzed sample. Thus, information theory can be useful and the quantities characterizing the information properties of an analytical method may be applied not only as evaluation criteria but also as objective functions in the optimization. The usability of information theory is demonstrated on the example of neutron activation analysis. Both precision and bias of NAA results are taken into account together with the possible use of reference materials for quality assessment. The influence of the above-mentioned parameters on information properties such as information gain and profitability of NAA results is discussed in detail. It has been proved that information theory is especially useful in choosing suitable reference materials for the quality assessment of routine analytical procedures not only with respect to matrix and analyte concentration in the sample but also to concentrations and uncertainties of certified values in the CRM used. In the extreme trace analysis, CRMs with relatively large uncertainties and very low certified concentrations can still yield rather high information gain of results.     

Redundancy and relevancy of analytical results in multielement analysis

From the point of view of the information theory, the term relevancy is actual only in the case of multielement determinations, because the information of one component determination is basically relevant. In the multicomponent determination the surplus of information, the s.c. redundancy, is given on the one hand by the relation between the information parameters of the analytical order and the equivalent parameters derived from the experimental data. On the other hand, the information from the individual terms of determined information parameters also have individual degrees of redundancy. But the given redundancy, the weight of information, is not necessarily always useful. The main problem is the correct and true determination of the given redundancy and following degree of relevancy.