J. Planar Chromatogr. 10, 118-120 (1997). Investigation of a computer-assisted retardation factor prediction system (RPS) for HPTLC of sixteen O-ethyl, N-isopropyl phosphoro(thioureido)thioates. The system is based on the use of three physicochemical parameters (hydrophobicity, substituent length, and substituent maximum width) which have high correlation with retardation factor (RF) in HPTLC. The RPS was evaluated by comparing measured RF values with those predicted. Good agreement was obtained between predicted data and experimental results.

J. Planar Chromatogr. 11, 300-304 (1998). Determination of the TLC retention of fifteen amino acids on silica gel layers developed with different mobile phases. Visualization with ninhydrin solution. Correlation analysis was conducted and fifteen parameters are discussed - including topological indexes and physicochemical properties - three of which were selected with both topological and physicochemical significance for construction of multi-parameter regression equations for prediction of the Rf values of the amino acids. Experimental results were in good agreement with calculated values, which confirms the accuracy of the predictions. - TLC of 15 amino acids on silica gel with ethanol - water 4:1, 8:1, 2:1 and propanol - acetic acid - water 3:1:1, 6:2:1, 1:1:1. Densitometry at 460 nm after visualization and heating for 1.5 - 2 min at 105°C.

Sz. Nyiredy, A. Kakuk (eds.): Planar Chromatography 2000, Lillafüred, Hungary, 24-26 June 2000, Res. Inst. for Med. Plants, p. 219-229. OPLC of 13 benzodiazepines on HPTLC silica gel with various calculated solvent mixtures up to 15 cm after a pre-run with acetone.

Proc. Intern. Symp. on Planar Separations, Planar Chromatography 2001, pp. 155-161. Photoacoustic spectroscopy was applied to investigate the effect of secondary chromatography on the in-depth distribution of compounds inside the sorbent on two types of TLC plates which were subject to different drying conditions. All investigated compounds demonstrated nonuniform vertical distribution with the tendency of considerably higher concentrations closer to the surface. TLC and HPTLC of a test dye mixture on silica gel with toluene.

J. Planar Chromatogr. 17, 192-199 (2004). TLC of 3-ethyloxycarbonyl-5-substituted-2,4-dioxotetrahydro-1,3-thiazole derivatives (2’-fluoro-6’-chlorobenzylidene, 1’-naphthylidene, 4’-methoxybenzylidene, 2’-oxybenzylidene, 2’-thienylidene, 4’-dimethylaminobenzylidene, 1’-carboethoxy-3’-indolylidene, 3’,4’-dimethoxybenzylidene, 4’-isopropylbenzylidene, benzylidene) on silica gel with non-polar diluent (hexane) - polar modifier (ethyl acetate, acetone, or dioxane) and on reversed-phase systems of the type rice starch with polar diluent (aqueous ammonia) - polar modifier (methanol, acetone, or dioxane). Examination of the dried plates after development under UV light at 254 nm.

J. Planar Chromatogr. 20, 267-274 (2007). Comparison of retention factors in pure water, log kw, determined by linear extrapolation and by a numerical method based on Oscik’s equation, and calculated values of log P as hydrophobicity indices for nine homologues s-triazines. The effect of mobile phase pH on solute retention was investigated as well as the effect of mobile and stationary phase properties on chromatographic behavior; 3 different organic modifiers (dioxane, acetonitrile, and tetrahydrofuran) and two stationary phases (RP-8 and RP-18) were used. Correlations of calculated log P values and log kw with carbon number confirm the usefulness of chromatographic techniques for studying the hydrophobicity of organic compounds. TLC on RP-18 with buffer - methanol mixtures in saturated sandwich chambers. Detection under UV light at 254 nm.

J. Chromatogr. A 1458, 136–144, (2016). The soil-water partition coefficient normalized to the organic carbon content (KOC) influences the fate of organic compounds in the environment. This paper proposes a RP-TLC method for KOC determination as a simpler, yet equally accurate method as the official HPLC method. TLC on different systems, including RP-18 and cyano phases developed with methanol – water and acetonitrile – water mixtures. 50 different compounds such as phenols, benzodiazepines, triazine herbicides, and polyaromatic hydrocarbons were selected. A calibration set of 29 compounds with known logKOC values was used to build simple univariate calibrations, Principal Component Regression (PCR) and Partial Least Squares (PLS) models between logKOC and TLC retention parameters. The models exhibit good statistical performance and indicate that the cyano phase contributes better to logKOC modeling than the RP-18 phase. Comparison of the proposed TLC methods, the official HPLC method, and four in silico estimation approaches by using the non-parametric Sum of Ranking Differences(SRD) approach. The best estimations of logKOC values were achieved by simple univariate calibration of TLC retention data from cyano phase developed with 40–50 % methanol. In a Linear Solvation Energy Relationship study it was found that the more polar cyano phase in combination with methanol – water mixtures is the key to better modeling of logKOC through significant diminishing of dipolar and proton accepting influence of the mobile phase as well as enhancing molar refractivity in excess of the chromatographic systems.

Phytochemistry 28, 87-981 (1989). TLC of pisatin and maackiain on silica with chloroform - methanol 4:1. Detection with vanillin - HCl reagent. Determination of RM: TLC on RP-18 254 plates activated by heating at 120°C for 15 min. with acetonitrile - water 13:7. Visualization under UV and by exposing to iodine vapor.