Economical Aspects of Analytical Information

1 The Role of Chemometrics in the Analytical Process 1.1 Economical Aspects of Analytical Information 

In its narrow sense, chemical analysis is an activity of obtaining information on the identity or on the quantitative composition of a sample. By chemical analysis an analytical result is produced, which may be one or more numbers, or one or more compound names. Why do analysts, or in general analytical laboratories, produce these numbers and names This question has been addressed by several analytical chemists 

The proposed answers vary from because everyone does to because we think that the analytical results contain relevant information for the customer who asked for the analysis . Another often mentioned reason is simply because the customer asked for it . As Massart pointed out, it is to be hoped that your own answer is not this last one, but is instead tecause we think the value of the information present in the analytical result is more worth than the cost of obtaining it . This means that analytical information has an economical value. This fact confronts us with three problems, namely how can we quantify the amoimt of information, or the quality of information present in the analytical data What are the cost of chemical analysis How to quantify the economical value of analytical information  

Intuitively we can feel that the economical value of the analytical result is related to its quality. The quality of an analytical result depends upon two factors first of all we should know how confident we are about the produced result. In fact, an analytical result without an explicit or implicit (by the number of significant figures) indication of its precision has no quality at all. Second, the quality of the analytical result depends on how well the sample represents the system of its origin. The sample may be contaminated or may be modified because of inappropriate storage and aging. In other instances, when the sample is taken from a chemical reactor in which a chemical reaction is occurring, the constitution of the reactor content is usually time varying. Because of inevitable time delays in the analytical laboratory, the constitution of the sample will not anymore represent the actual constitution in the reactor at the moment when the analytical result is available. Therefore, both the precision of the analytical method and the analysis time are important indicators for the quality of an analytical result .  

This requirement of being able to attach a quality label to our analytical results, made that statistics and the statistical treatment of our data have become of a tremendous importance to us. This is reflected by the fact that in 1972 ANALYTICAL CHEMISTRY started with the publication of a section on Statistical and Mathematical Methods in Analytical Chemistry in its bi-annual reviews. Although we feel us quite confident on how to express our uncertainty (or certainty) in the produced numbers, we are less sure on how to quantify our uncertainty in produced compound names or qualitative results. 

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