J. AOAC Int. 93, 787-791 (2010). HPTLC of omeprazole on silica gel with chloroform - methanol 9:1 in a twin-trough chamber after saturation for 20 min. Quantitative determination by absorbance measurement at 302 nm. The hRf value of omeprazole was 39. Linearity was between 50 and 3000 ng/band. The intra-day and inter-day precision was 0.4-0.5 and 0.8-0.9 % (n = 2). The recovery was 98.4-99.1 %. LOD and LOQ were 8 and 24 ng/zone, respectively.

J. Chromatogr. 405, 394-400 (1987). One- and two-dimensional TLC on octadecyl-bonded silica with different solvents or solvent combinations. Discussion of the chromatographic characteristics with different parameters.

J. Chromatogr. 672, 203-211 (1994). Test of the ability of the molecular connectivity model to predict Rf values in TLC for a group of sulfamides using multi-variable regression equations with multiple correlation coefficients, standard error of estimate, F-Snedecor function values and Student's t-test as criteria of fit. Prediction of the values for this property in different silica and different polar mobile phases by using the molecular connectivity model. Discussion of the relationship between structural features of sulfamides and the Rf values in TLC.

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. Planar Chromatogr. 24, 474-481 (2011). TLC of the active S-(+)-enantiomer escitalopram oxalate (ESC-OX), escitalopram cyanodiol, the R-enantiomer and escitalopram N-oxide impurities on silica gel (containing beta-cyclodextrin as chiral additive) with acetonitrile - 0.1 % acetic acid - water 10:1:6:2 with chamber saturation for 30 min. Using 3 mg urea per 100 cm2 of silica-coated plates as a chiral additive also achieves a good enantiomeric separation with acetonitrile - 1 % acetic acid - ethyl acetate - methanol - water 10:1:2:4:3. Detection at 254 nm. Quantitative determination by absorbance measurement of ESC-OX at 240 nm. The hRf values of ESC-OX, escitalopram cyanodiol, the R-enantiomer and escitalopram N-oxide were 75, 40, 31, and 23, respectively. The linearity was 0.25-10 mg/10 mL (r = 0.9991). Accuracy was 99.7 %. LOD and LOQ were 13 and 44 µg/mL for ESC-OX.

Anal. Biochem. 172, 484-487 (1988). HPTLC on silica with butyl acetate - ethyl acetate 5:1, chloroform - butyl acetate - ethyl acetate 3:3:1, chloroform - butyl acetate - ethyl acetate -triethylamine 12:2:4:1. Preservation of the chromatograms by dipping in 10% paraffin oil in cyclohexane and heating. Quantification by fluorodensitometry at 366/>400 nm. Detection limit, 1-4 p mol.

Chromatographia 40, 96-98 (1995). Study of the behavior and separation ability of cellulose, starch and aminoplast thin-layers with aqueous and non-aqueous mobile phases by measuring the retention of a homologous series of benzamides. Discussion of the retention behavior and separation ability in terms of the nature of the solute, support and eluent.

Analytical Science 25(1), 57-62 (2009). HPTLC of minocycline on silica gel plates previously treated with 10 % EDTA solution of pH 9.0 with methanol - acetonitrile - isopropyl alcohol - water 10:8:1:1. The hRf value was 32. Densitometric evaluation at 345 nm. The method was linear in the range of 100-1200 ng/band for all biological samples. The average recovery was 95.1 %. The method was found suitable for estimation of the drug in different biological fluids (human plasma, saliva, gingival fluid) and can be used for pharmacokinetic studies.