J. Planar Chromatogr. 3, 264-268 (1990). Comparison of various diluent + modifier - silica systems for 57 solutes by graphical methods; i.e. RM vs. eluent spectra plotted on the basis of equieluotropic series of RM1 vs. RM2 correlations. The spread of points was largest when the binary eluents differed in both diluent and modifier. The differentiated selectivity characteristics of the diluent - modifier binaries demonstrate good prospects for computer-aided selection of an optimal system for TLC analysis of a given set of compounds from the data base.

J. Chromatogr. 593, 329-337 (1992). Study of the retention behavior of 14 closely related coumarins in normal-phase TLC and HPLC with the aim of testing the suitability of TLC as a pre assay of HPLC when the optimization of the mobile phase has been carried out according to the PRISMA system. Measurement of the retention in TLC and HPLC at 37 and 13 selective points, respectively. Two and three dimensional evaluations of capacity factor k' against selectivity points showed similar retention behavior for the coumarins in TLC and HPLC. Discussion of the dependency of k' on the change in solvent strength.

J. Planar Chromatogr. 8, 341 - 345 (1995). Description of the vertical and horizontal correlations between the hRf values of apolar compounds and the selectivity points at constant and different solvent strength levels in saturated TLC chambers. - HPTLC of furocoumarins on silica, of anthraquinones on silica CN-phase and of opium alkaloids on NH2 silica with multicomponent solvent systems (dichloromethane, tetrahydrofuran, chloroform, n-hexane; ether, tetrahydrofuran, ethyl acetate, hexane; ethyl acetate, acetone, dichloromethane, hexane, methanol). - Anthraquinone aglycones: rhein, aloe-emodin, emodin, physicon, chrysophanic acid; furocoumarin isomers: bergaptene, iso-bergaptene, shondin, pimpinellin, iso-pimpinellin, xanthotoxin, angelicin, psoralen; opium alkaloids: morphine, codeine, narcotoline, thebaine, papaverine, narcotine. Densitometry at 425 nm (anthraquinones), or 280 nm (opium alkaloids).

J. Liq. Chrom. & Rel. Technol. 22, 1429-1441 (1999). Presentation of a new mathematical model for the optimization of the eluent composition used for the separation of a mixture of 1,4-benzodiazepines. HPTLC of 1-chlordiazepoxide, oxazepam, nitrazepam, medazepam and diazepam on silica gel with chloroform - acetone - isopropanol mixtures in different compositions. Quantitation by densitometry in reflectance mode at 254 nm.

J. Planar Chromatogr. 3, 417-421 (1990). Retention versus eluent composition relationships of 36 drugs and poisons have been determined using silica gel and 20 binary eluents - mixtures of four weakly polar diluents (heptane, chloroform, dichloromethane, and trichloroethylene) and four polar modifiers (MEK, ethyl acetate, ether, diisopropyl ether) or mixtures of the four polar modifiers with methanol. In accordance with the Snyder-Soczewinski model of adsorption, linear relationships of the type RM = RM - m log cmod were obtained in almost all cases.

Chromatographia 35, 102-108 (1993). Study of the optimization of TLC parameters. Comparison of the window diagram and overlapping resolution map methods. Use of the latter to take into account the spot diameter and the average plate height variations with the development distance, in order to improve the reliability of the method.

J. Planar Chromatogr. 8, 319-323 (1995). Application of a test mixture (thymol blue, methyl red, bromothymol blue, oracet blue) on silica with an automatic TLC sampler. Followed by radial development with a selection of solvents also delivered by the automatic TLC sampler. Chromatograms can be obtained by densitometry. Inspection enables selection of the approximate solvent strength (Snyder’s solvent classification table) for the separation. The results indicate which solvent group has the required selectivity. So a suitable solvent system can generally be determined in two to three methodical steps. Rapid, cost-effective method requiring minimal solvent and sample consumption.

J. Liq. Chrom. & Rel. Technol. 22, 15-27 (1999). Investigation of the dependence between retention of five different test solutes and the mobile phase composition in TLC systems with 3-cyanopropyl modified silica gel and binary 2-propanol - n-hexane eluents; calculation of regression parameters and conclusions regarding efficiency of the retention models.