Chemometrical Interpretation of Analytical Data

The ultimate purpose of analytical studies is rarely a set of analytical results (data set) but frequently chemical information about the subject under investigation. Chemical information may concern properties like  

Data interpretation always becomes difficult if several properties of various objects (samples) have to be considered simultaneously. 

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Chemometrics has found widespread use in the interpretation of analytical data and is relied on for the development of NIRS methods. 

A comprehensive two-volume Handbook of Chemometrics and Qualimetrics has been published by D. L. Massart et al. (1997) and B. G. M. Vandeginste et al. (1998) predecessors of this work and historically interesting are Chemometrics A Textbook (Massart et al. 1988), Evaluation and Optimization of Laboratory Methods and Analytical Procedures (Massart et al. 1978), and The Interpretation of Analytical Chemical Data by the Use of Cluster Analysis (Massart and Kaufmann 1983). A classical reference is still Multivariate Calibration (Martens and Naes 1989). A dictionary with extensive explanations containing about 1700 entries is The Data Analysis Handbook (Frank and Todeschini 1994). 

One possibility is to classify the methods used in the various steps of the analytical process (see also Section 1.5). Note that the analytical process usually starts with the definition or selection of the matter to be investigated. Here it is very important to realize that every sample or object of investigation has a history. Because this history may cause severe systematic errors, THIERS [1957] explains Unless the complete history of any sample is known with certainty, the analyst is well advised not to spend his time in analyzing it. Clearly, in such circumstances one should be extremely cautious about drawing conclusions from chemometric interpretations even where data are available. 

Application of Chemometrics to the Interpretation of Analytical Separations Data... 

EXMAT - A Linked Network of Expert Systems for Materials Analysis. Seven individual expert systems comprise EXMAT (1) problem definition and analytical strategy (2) instrumental configuration and conditions (3) data generation (4) chemometric/search algorithms (5) results (6) interpretation (7) analytical goals. Dynamic headspace (DHS)/GC and pyrolysis GC (PGC)/concentrators... 

When confronted with an analysis, the problem must be tackled methodically. The science called chemometrics is aimed at helping to find the best method required for solving an analytical problem as a function of imposed constraints and according to three different directions methodology, data treatment and interpretation of results. 

Whereas there has been a huge interest in multimode calibration in the theoretical chemometrics literature, there are important limitations to the applicability of such techniques. Good, very high order, data are rare in analytical chemistry. Even three-way calibration, such as in DAD-HPLC, has to be used cautiously as there are frequent experimental difficulties with exact alignments of chromatograms in addition to interpretation of the numerical results. However, there have been some significant successes in areas such as sensory research and psychometrics. 

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