Identification of drugs by principal components analysis of Rf data obtained by TLC in different eluent systems.

The retention factor of 54 drugs in eight eluent mixtures is reported. Principal component analysis (PCA) of these data provided a significant two-components model. These two parameters characteristic for each drug allowed an objective identification of unknown samples, provided they were included in the considered set. The analysis showed that the eluent mixtures cluster into three groups. The PCA model, using only three eluents (one for each group), was also able to restrict the range of inquiry to a few "candidates" and, in some cases, to allow unambiguous identification of the drug. These results, based on a simple and quick analytical determination (thin layer chromatography) and a reliable statistical procedure (PCA), appear to be of significant practical importance in the field of analytical toxicology.