Thin-layer chromatographic study of the lipophilicity of triazine herbicides

Quantitative structure—retention and retention—activity relationships of some 1,3-oxazolidine systems by RP-HPTLC and PCA

A quantitative structure-retention and retention-activity relationships investigations were performed on the lipophilicities of some 1,3-oxazolidine systems as estimated by RP-HPTLC retention parameters. The classical R(Mo) values were compared with the factors scores obtained by principal component analysis based also onto the TLC retention data. The lipophilicities (R(Mo) and factor scores) were correlated with the theoretical molecular descriptors of 1,3-oxazolidine derivatives providing by the ALCHEMY 2000 software package. The reliability of the factor scores values as lipophilic indices are shown by their significant correlation with the classical R(Mo) values and other molecular descriptors. In addition, the "lipophilicity chart" described by the first two components, and/or the "lipophilicity space" described by the first three components have the effect of separating compounds from each other most effectively from the congeneric (similarity) aspect point of view. Finally, these findings support the idea that the chromatographic process of the investigated compounds in this paper and consequently their partitioning over a bio-membrane are controlled mainly by lipophilicity.

Evaluation of lipophilicity of some benzimidazole and benztriazole derivatives by RP HPTLC and PCA

The lipophilic character of some benzimidazole and benztriazole derivatives was studied. The classical R(Mo) values were compared with the factors scores obtained by principal component analysis (PCA) based also onto the TLC retention data. The very high correlation between the R(Mo) values and slopes (specific hydrophobic surface area) indicated as usually that this group of compounds could be considered as a homologous series independently of their structural heterogeneity. It is emphasized once again that this procedure can not be a rational and objective way for congeneric studies because always there is a high correlation between slope and intercept. The reliability of the factor scores values as lipophilic indices are shown by their high correlation with the classical R(Mo) values. In addition, the 'lipophilicity chart' described by the first two components has the effect of separating compounds from each other most effectively from the congeneric aspect point of view. The most lipophilic compounds appeared to be the benzimidazole derivatives.

Analysis of pesticide residues in drinking water by planar chromatography

Planar chromatography is described in the field of water analysis. The principle of automated multiple development (AMD) technique is mentioned, the strategy of the whole procedure which became a German standard is demonstrated and separations of pesticide mixtures, as well as water samples containing pesticides are presented. The suitability of this method was proved for 283 pesticides and the corresponding ISO Standard has been applied for.