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. 27, 1999-2020 (2014). HPTLC of methocarbamol in pharmaceutical mixtures with ibuprofen, paracetamol and diclofenac sodium and in the presence of its degradation product guaifenesin on silica gel with chloroform - methanol 47:3. Quantitative determination by absorbance measurement at 264 nm. A chemometric handling of the TLC peak responses involving the convolution of the derivative curves using 8-points sin x i polynomials, allowed the analysis of different mixtures of methocarbamol with enhancing of the regression parameters.

J. Planar Chromatogr. 10, 114-117 (1997). Using the analysis of addictive substances as an example an overview is given of the use of eight different development techniques to illustrate the improvements of the efficiency of thin-layer chromatography. Optical comparison of chromatograms and determination of separation numbers are used to provide information about the separation performance of each system. A comparison has been made of AMD, ADC and normal chamber developments of HPTLC and TLC plates with and without chamber saturation. The separation performance has been investigated using separation numbers according to Geiss and Kaiser. The highest separation number (23.5) was obtained by use of AMD. Separation numbers of approximately 18 were obtained with HPTLC plates. The worst separation numbers (7.7-15) were, as expected, obtained with TLC plates. The improvements in TLC techniques over recent years are emphasized. Substances chromatographed: anthranilic acid, codeine, DMT, etryptamine, morphine, DOB, theobromine, Sudan III.

Acta Chromatographica 22 (2), 267-279 (2010), DOI:10.1556/AChrom.22.2010.2.9. Presentation of a general equation for modeling retention, using the organic modifier content of the mobile phase, which is based on the Box-Cox transform of modifier concentration. Both the semilogarithmic relationship (Soczewinski-Wachtmeister equation) and logarithmic relationship (Snyder-Soczewinski equation) are found to be special cases of the proposed equation. The equation can be fitted easily with free software and an additional coefficient can be interpreted as closeness to the previous models. The equation enables extrapolation to zero modifier content even with strong closeness to log-log dependence. Discussion of a case study on nine drug-like substances, with comparison of 14 previously proposed retention equations found in the literature.

Analyt. Chemistry 54, 1955-1959 (1982). A method is described for predicting the optimum combination of solvent path length and binary solvent composition for obtaining a given separation between a pair of compounds in the minimum time by continuous development TLC. The continuous development of a pair of dyes and a pair of steroids is presented to illustrate the agreement between predicted and experimental analysis time and spot separation.