Encyclopedia of Chromatography Third Edition 1, 874-877 (2009). The author describes the application of TLC to predict the optimum isocratic and gradient eluent composition in traditional and modern flash chromatography. For method development, the hRf should be between 15 and 35 for the component of interest. A relationship between hRF and column volumes for FC is proposed and solvent strenght calculations for different systems are described.

Drug Development and Industrial Pharmacy 35, 440-448 (2009). TLC of tacrolimus on silica gel with toluene - acetonitrile - glacial acetic acid 60:40:1. For quantitative evaluation the plate was derivatized with anisaldehyde sulfuric acid reagent and scanned at 675 nm. Using this method a compact spot was obtained at an hRf value of 40. The linearity range was 100-800 ng/band. The method is suitable for routine analysis of formulations.

Research Journal of Pharmaceutical, Biological and Chemical Sciences 1(2), 226-234 (2010). TLC on silica gel with toluene - isopropanol - 25 % ammonia 23:23:4. The hRf value was 30. Densitometric evaluation at 258 nm. The linearity range was 100-350 ng/band. For stability studies diacerein was subjected to different stress conditions (acid, alcohol, oxidative, thermal, photolytic). Degradation products were well resolved from the main zone of diacerein with significantly different hRf values.

Asian J. Chemistry 22(1), 27-30 (2010). HPTLC of simvastatin (in bulk and tablet dosage form) on silica gel with toluene - ethyl acetate - formic acid 10:3:1. The hRf value of simvastatin was 26. Densitometric evaluation at 242 nm. The method was linear in the range of 200-1000 ng/band.

Asian Journal of Chemistry 22(10), 8117-8120 (2010). HPTLC of beta-sitosterol in leaves, roots and seed oil of 3 species of Jatropha. Chromatographic separation on silica gel with toluene - methanol 9:1. The hRf value of beta-sitosterol was 54. Derivatization with anisaldehyde-sulfuric acid reagent, followed by heating at 120 °C. After derivatzation densitometric evaluation at 525 nm. The method was linear in the range of 100-500 ng/band. The proposed method was used for the estimation of beta-sitosterol in extracts of different species of plants. The presence of beta-sitosterol in samples was confirmed by multi-wave length scanning.

Chem. Anal. (Warsaw) 54, 1-12 (2009). An HPTLC method has been developed for estimation of modafinil in tablet formulation and stability assessment. HPTLC on silica gel with toluene - chloroform - methanol 2:2:1. The hRf value of modafinil was 46. Densitometric evaluation at 220 nm. The method was linear in the range of 100-500 ng/band. The sample compound was well separated from all degradation products. The method was suitable for analysis and also for stability studies.

J. AOAC Int. 93, 1180-1191 (2010). TLC of tropisetron and its acid-induced degradation products on silica gel with methanol - glacial acetic acid 22:3 with chamber saturation for 45 min. Detection under UV light at 254 nm. Quantitative determination by scanning at 285 nm. The hRf values were 44, 84, and 92 for tropisetron and degradates I and II, respectively. Linearity was between 1 and 10 µg/zone. Mean accuracy was 100.2 %. The precision was 0.64 %.The limit of detection and quantification for tropisetron was 0.26 and 0.80 µg/zone, respectively. The intraday and interday precisions were evaluated by assaying freshly prepared samples of tropisetron in triplicate concentrations, i. e. 3, 5, and and 9 µg/zone, resulting in 99.8 %, 100.3 %, and 100.4 %, respectively, for interday precision and 99.7 %, 100.2 %, and 99.7 %, respectively, for intraday precision (with a precision of 0.9 %, 0.6 %, 0.8 % and 0.6 %, 0.4 %, 0.6 %, respectively).

Phytochem. Anal. 22, 59-65 (2011). TLC and free radical scavenging fingerprints of nineteen Salvia species on silica gel with toluene - ethyl acetate - formic acid 60:40:1 for the less polar constituents and ethyl acetate - water - formic acid - acetic acid 100:26:11:11 for the medium and highly polar substances. After drying at room temperature for 15 min derivatization with vanillin sulfuric acid reagent (1 g vanillin with 20 % sulfuric acid in methanol) followed by heating for 5 min at 105 °C. Quantitative determination by absorbance measurement at 254 nm. Free radical scavenging properties were investigated by spraying the plate with DPPH radical reagent (0.2 %) in methanol and left at ambient temperature for 30 min. The strongest free radical scavenging activity was observed for rosmarinic acid, with an hRf of 70.