Chemometrics in Europe - Selected results

Abstract

to recalculate the concentration profiles. This process (truncation, normalization and pseudoinverse followed by pseudoinverse) was repeated until no further refinement occurred.The concentration profiles and spectra of the three unknown components of stearyl alcohol in carbon tetrachloride obtained in this manner were found to make chemical sense.This EFA procedure, unlike others, was successful in extracting concentration profiles from situations where one component profile was completely encompassed underneath another component profile.References [I] Malinowski, E. R., and Howery, D. G., Factor Analysis in Chemistry, Wiley Interscience, New York (1980). [2] Gemperline, P. G., J. Chem. Inf. Comput. Sci. 24, 206 (1984).[3] Vandeginste, B. G. M., Derks, W., and Kateman, G., Anal.Chim. Acta 173, 253 (1985). [4] Gampp, H., Macder, M., Meyer, C. J., and Zuberbuhler, A.D., Talanta 32, 1133Talanta 32, (1985.[5] Malinowski, F. R., J. Chemometrics 1, 33 (1987).[6] Wold, S., Technometrics 20, 397 (1978). Chemometrics in Europe:Selected Results Wolfhard WegscheiderInstitute for Analytical Chemistry Mikro-and Radiochemistry Technical University Graz, A-8010 Graz, AustriaChemometrics is a very international branch of science, perhaps more so than chemistry at large, and it is therefore appropriate to question the suitability of the topic to be presented. It is, however, the author's opinion that the profile of European chemometric research has a couple of distinct features that may originate more in the structure of the educational system than in the actual research topics. The profile as it will be presented is the one perceived by the author, and therefore comprises a very subjective selection of individual contributions to the field. Obviously, this is not the place to offer a review on chemometrics, let alone one that is restricted to a continent.The definition of chemometrics [I] comprises three distinct areas characterized by the key words "optimal measurements," "maximum chemical information" and, for analytical chemistry something that sounds like the synopsis of the other two: "optimal way [to obtain] relevant information." Information TheoryEckschlager and Stepanek [2][3][4][5] where q and p are the prior and posterior distribution of the analyte concentration for the specific cases of a rectangular prior distribution in (x,,x 2 ) and a Gaussian posterior with a standard deviation s determined from /A independent results. The penalty for an inaccurate analysis is considerable and can be expressed as (2) I (r;q,p)= I (q 11P)_nA with d the difference between obtained value and the true value of x. The concept has also been extended to multicomponent analysis and multimethod characterization.In the latter case, correlations between the information provided by the different methods need to be accounted for. Given the cost of and time needed for an analysis, information efficiency can be deduced in a straightforward manner [2]. Recently, work was published [5] suggesting the incorporation of various relevance co...