OPTIMUM SELECTIONS AND COMBINATION OF SOLVENT SYSTEMS IN THIN-LAYER CHROMATOGRAPHY, USING THE FUZZY SET-THEORY

A rational selection of a restricted set from 15 available chromatogra phic systems for the separation of all compounds structurally related to nitroxoline and 8-hidroxyquinoline derivative is discussed. For the selection of a preferred combination of two or more systems, three ap proaches are possibile, The first is to consider every possibile combi nation of two more chromatographic systems and to calculate the inform ation content or discriminating power for each combination. The second and the third approach is to classify the chromatographic systems int o dissimilar groups and to select from each group (with similar separa tion characteristics) the best system according to the information con tent or quality partition coefficient and degrees of membership. The c lassification is carried out by using the classical numerical taxonomy and the fuzzy set theory. The results obtained by applying these tech niques appear to be similar but the fuzzy algorithm is more consistent and allows a more rational classification and selection of separating system in TLC.