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tions of Salina herbs are diverse, because of the different pharmacological activity of the species. Some are used as alimentary tract stimulators and digestion regulators, with additional antiseptic properties. Other Salina species are known for theii antipyretic, analgesic, and expectorant properties, and are readily applied in therapy of influenza and colds. Yet other species are used in therapy of psychoses, depression, and neuroses, because of the sedative properties of the respective decocrions. Application of sagę against menstruation disorders has also been reported [5].

There has recently been substantial growth of interest in characteriza-tion of the Chemical contents of a sample by use of its analytical signal, which is regarded as a sample fingerprint [6]. The use of fingerprinting strategies and methods is steadiiy attracting attention, e.g. for ąuality con-trol of herbal medicines [6], in the petroleum industry [7], in biotechnology for peptide mapping [8, 9], or in tracing the origin of some products [10]. Among the different analytical techniques well suited to fingerprinting, chromatographic methods have their special place, because they enable separation and quantification of the components of the mixtures analyzed. For very complex samples (like those of natural origin), chromatograms (fingerprints) are often used for characterization and comparison, because of the high cost or the lack of chromatographic standards.

The task of comparative analysis of the samples represented by their chromatographic fingerprints can largely be facilitated by use of a variety of chemometric techniques, which include approaches that help to preprocess the chromatographic data [11], evaluate differences among the samples [12], estimate the number of components in a sample [13,14], and visualize mul-hvariate data [15].

For most applications, before further chemometric analysis, chromatographic fingerprints require some preprocessing to take their potential de-ficiencies into account. This step is very important, because it can hamper reaching overall conclusions about differences among the samples. Preprocessing of chromatographic fingerprints is a very chailenging task and great care should be taken when a few preprocessing methods are used sequen-tially. Depending on the type of the sample and the technique selected, the fingerprints obtained contain different information. Therefore, preprocessing methods applied to chromatographic fingerprints ought to emphasize the underlying differences among the samples related to their Chemical composition only, suppress undesired instrumental variations, and enhance the signal-to-noise ratio of the individual fingerprints.

In this paper, we focus on aspects of preprocessing of the chromatographic fingerprints of the twenty different sagę (Salina L.) species and on their comparative analysis. The comparative analysis is performed for two sets of fingerprints. The first set of fingerprints was obtained by use of high-