J. Chil. Chem. Soc. 48, 19-23 (2003). HPTLC validation of atrazine in aqueous extracts of soils on silica gel (layer thickness 100 µm) previously activated at 120 ºC for 30 min. The elution program applied to aqueous soil matrices started with 10 short isocratic runs (0.8 min) with acetonitrile – dichloromethane 30:70. Mixer was emptied after the tenth step and refilled to continue with 4 successive isocratic runs (2.5, 5.0, 7.5 and 25 min) with dichloromethane. The plate was dried for 1 min between each step and for 3 min after the last one. The plate was preconditioned with nitrogen for 15 s before each run. Quantitative determination by absorbance at 210 nm. Linearity is between 5 and 100 ng and recoveries ranging from 98.7 to 103.5 %. The detection limit is 1.5 ng and the quantification limit is 4.9 ng. Precision analysis shows an intra-assay variation between 1.48 and 5.47 %. The method can be applied to a broad range of soils including those with high organic matter content.

J. Planar Chromatogr. 19, 260-266 (2006). AMD-HPTLC of bezafibrate, ciprofibrate, clofibric acid, clofibrate, fenofibrate, and gemfibrozil on diol phase with mixtures of tetrahydrofuran and hexane. An 25 % aqueous solution of acetic acid was used for preconditioning. Quantitative determination by absorbance measurement at 227 and 254 nm.

Acta Chrom. 16, 153-163 (2006). HPTLC of salicylamide in diuretic tablets and pain-relief tablets on silica gel with concentrating zones (pre-washed with dichloromethane - acetone 1:1) with dichloromethane – acetone 4:1. Quantification by densitometry at 254 nm. The method is suitable for routine quality-control analysis of pharmaceuticals containing salicylamide.

J. Liq. Chromatogr. Relat. Technol. 29, 1891-1903 (2006). HPTLC of androsterone, epi-androsterone, dehydro-epi-androsterone, testosterone, stigmasterol, beta-sitosterol, estradiol, hydrocortisone, and cholesterol on RP-18 W with methanol - water, and acetonitrile - water in different composition, with chamber saturation. Detection by spraying with sulfuric acid - methanol 1:9 and heating at 120 °C for 15 min. Densitometric determination of RF values. The aim of the work was to compare the lipophilicity of selected steroids determined by RP-HPTLC on RP-18 W plates using different mobile phases with lipophilicity values estimated by computational methods.

J. AOAC Int. 90, 142-146 (2007). HPTLC of pantoprazole [5-(difluoromethoxy)-2-[(3,4-dimethoxy-2-pyridyl)methyl-sulfinyl]1H-benzimidazole] and domperidone (5-chloro-1-[1-[3-(2,3-dihydro-2-oxo-1H-benzimidazol-1-yl)propyl]-4-piperidinyl]-1,3-dihydro-2H-benzimidazol-2-one) on silica gel with ethyl acetate - methanol 3:2 in a twin-trough chamber saturated for 30 min. Quantitative determination by absorbance measurement at 287 over the concentration range of 80 - 240 and 60 -180 ng/spot with mean recovery of 98.4 +/- 0.7 % for pantoprazole, and 98.8 +/- 0.7 % for domperidone.

J. Liq. Chromatogr. & Relat. Technol. 30, 1749-1762 (2007). HPTLC of omeprazole (5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole) and domperidone (5-chloro-1-[1-[3-(2,3-dihydro-2-oxo-1H-benzimidazol-1-yl)propyl]-4-piperidinyl]-1,3-dihydro-2H-benzimidazol-2-one) on silica gel with ethyl acetate - methanol - benzene 2:1:2. Quantitative determination by absorbance measurement at 295 nm.

Biomed. Chromatogr. 21 (10), 1064-1068 (2007). Indirect chiral separation of penicillamine (3,3-dimethylcysteine) enantiomers after derivatization with Marfey's reagent (FDNP-Ala-NH2) and two of its structural variants, FDNP-Phe-NH2 and FDNP-Val-NH2, with phenol - water 3:1 and solvent combinations of acetonitrile and triethylamine phosphate buffer in normal and reversed-phase TLC, respectively. Also separation of the diastereomers on a reversed-phase HPLC column with gradient elution of acetonitrile and 0.01 m trifluoroacetic acid. Comparison of the results due to these three reagents. Successful application of the method for checking the enantiomeric impurity of l-penicillamine in d-penicillamine and to check the enantiomeric purity of pharmaceutical formulations of d-penicillamine.

J. Sep. Sci. 30, 2786-2793 (2007). HPTLC of unsaponifiable constituents of rice bran oil on silica gel in two stage separation: First separation with benzene – chloroform 12:1 for sterols, oryzanols, and tocols. Quantitative determination by absorbance measurement at 206 nm for sterols (1), 325 nm for oryzanols (2), and 297 nm for tocols (3). Second separation with petroleum ether – diethyl ether 50:1 for steryl esters (4), wax (5), and squalene (6). Detection by dipping in 5 % methanolic sulphuric acid followed by heating at 110 °C for 1 hour. Quantitative determination by absorbance measurement at 439 nm. The hRf values were 12 for (1), 21 for (2), 39 for (3), 36 for (4), 46 for (5), and 74 for (6). Linearity was between 150 and 1200 ng/zone for the first separation and between 400 and 1200 ng/zone the second separation. The limits of detection and quantification were 6 and 20 ng/zone for (1), 1 and 4 ng/zone for (2), 11 and 38 ng/zone for (3), 22 and 73 ng/zone for (4), 19 and 65 ng/zone for (5), and 3 and 10 ng/zone for (6), respectively. Intra-assay precision was between 0.52 and 1.94 % and inter-assay precision was between 0.87 and 2.27 %. Recoveries ranged from 93.5 to 101.9 %.