J. Planar Chromatogr. 2, 203-206 (1989). The chromatography of six N-oxides (nicotinic acid N-oxide, metyrapone N-oxide, p-cyano-N, N-dimethyl aniline N-oxide, 3-acetyl pyridine N-oxide, 3-benzylpyridine N-oxide, and pyridine N-oxide) was described for both C-18 and CN-bonded silica gel TLC plates. Using methanol-water solvent systems containing up to 60% methanol the N-oxides had higher Rf values than their respective parent compounds. At concentrations of methanol of 80% or more the order of migration was reversed. Separation of critical pairs was possible by careful selection of one or other of the phases.

J. Planar Chromatogr. 5, 435-440 (1992). Separation of selected position and geometric isomers by thin layer adsorption chromatography; correlation of Rf and RM values with the numerical values of the topological indexes. Based on the correlation it has been possible to propose an original chromatographic rule which can be used to predict the order of elution of the isomers.

J. Chromatogr. 668, 495-500 (1994). Determination of the retentions of 26 commercial pesticides by TLC on alumina with hexane - dioxane mixtures, and by HPLC with an alumina column. discussion of the linear intercorrelation between the log k' and RM values of the pesticides with the concentration of dioxane in the eluent.

J. Planar Chromatogr. 8, 366 - 368 (1995). Study of the retention behavior of a series of para-substituted anilides on silica with nonaqueous mobile phases. The results were discussed in terms of the nature of the solute and the eluent. - TLC of N-substituted amides, N-substituted benzamides, and N-substituted a-phenylacetamides on silica with 8 different mobile phases; spots were observed under UV 254 nm.

J. Chromatogr. A 719, 45-51 (1996). Study of the relationship between the RM values obtained by TLC for phenols and connectivity indices. Presentation of the corresponding connectivity functions, selection based on their respective statistical parameters by using multivariate regression, and a correct prediction of the experimental elution sequence for the molecules using silica layers and mobile phases of different polarity. Random and stability studies of different prediction models.

J. Planar Chromatogr. 10, 406-410 (1997). To study the relationship between chemical structure and retention behavior in TLC on silica, the retention constants of variously substituted 1,2-O-isopropylidene derivatives of aldohexoses and 1,2-O-cyclohexylidene derivatives of aldopentoses were measured as a function of the composition of eight binary mobile phases. The slopes and intercepts of the linear relationships between the retention constant (RM) and the logarithm of the volume fraction of the polar mobile phase component were calculated and are discussed in relation to solute and mobile phase characteristics. The RF values and relative retention of compounds depend largely on the retention behavior of their substituents.

J. Chromatogr. A 847, 291-296 (1999). TLC of 16 neutral and cationic complexes containing from five-to seven-membered diamine chelate rings on thin layers of silica cellulose and polyacrylonitrile sorbents with six aqueous solution of ammonium sulfate at various concentrations. Establishment of hRf decreasing with increasing ring size in all of the instances, and Rm values being a linear function. Discussion also of the effect of salt concentration. Proposal of a mechanism based on hydrophobic interaction between the sorbend and sorbent.

Part 2. The lipophilicity of 1,6-diaryl-5,7(1H)dioxo-2,3-dihydroimidazo[1,2-a][1,3,5]triazines and 1-aryl-5,6(1H)dioxo-2,3-dihydroimidazo[1,2-a]imidazoles. J. Planar Chromatogr. 13, 130-134 (2000). Determination of the lipophilicity of twenty five new carbonyl derivatives of 1-aryl-2-aminoimidazolines-2 (twenty 1,6-diaryl-5,7(1H)dioxo-2,3-dihydroimidazo[1,2-a][1,3,5]triazines and five 1-aryl-5,6(1H)dioxo-2,3-dihydroimidazo[1,2-a]imidazoles) by RPTLC on commercial RP-18 silica gel plates with methanol - acetic acid - water. RM values for all the compounds were linearly dependent on mobile phase methanol concentration within the range of 60 to 90%.