Asian J. Chem. 19(5), 3375-3381 (2007). The TLC method described in USP 28 does not separate all the related substances of alprazolam. An alternative HPTLC method is described for separation and estimation of starting material and synthesis related intermediates in alprazolam: 2-chloro acetamide-5-chloro benzophenone (impurity 1) i.e. starting material, nordiazepam (impurity 2), thionordiazepam (impurity 3), 2-(2-aceto hydrazinyl)-7-chloro-5-phenyl-3H-1, 4-benzodiazapine (impurity 4). The hRf values of alprazolam, impurity 4, impurity 3, impurity 2, and impurity 1 were 25, 16, 77, 45, and 83 respectively. The HPTLC method developed is capable of detecting impurities at a level of 0.05%.

Pharma Review 7(3), 168 - 170 (2008). HPTLC of amlodipine besilate and bisoprolol fumarate on silica gel with methanol - ethyl acetate - ammonia 50:60:5. Quantitative determination by absorbance measurement at 229 nm. The hRf values were 39 and 52 for amlodipine and bisoprolol respectively. The linear rangewas 500-1000 ng/spot for both components. The method was suitable for routine quality control of combine dosage form.

60th Indian Pharmaceutical Congress PA-198, (2008). HPTLC of simvastatin on silica gel with toluene - ethyl acetate - formic acid 16:3:1. Quantitative determination by absorbance measurement at 242 nm. The method was linear in the range of 200-1000 ng/spot and suitable for routine quality control of bulk drug and its dosage forms.

Asian J. Chem. 19(7), 5647-5651 (2007). HPTLC of levofloxacin hemihydrate and ornidazole on silica gel with n-butanol - water - acetic acid 3:1:1. Quantitative determination by absorbance measurement at 366 nm. The method was linear in the range of 1050-1400 µg/mL and 2600-2900 µg/mL for levofloxacin and ornidazole respectively. The recovery was between 97.3 and 98.0 % for both drugs. The method was suitable for simultaneous estimation of both drugs in combined tablet dosage form.

J. Planar Chromatogr. 22, 211-215 (2009). TLC of fat soluble vitamins (ergocalciferol, cholecalciferol, (+/-)-alpha-tocopherol, tocopherol acetate, retinol, retinol acetate, retinol palmitate, menadione, and phytonadione) on RP-8 and RP-18 (prewashed with methanol) with methanol - water in different volume proportions, with chamber saturation for 20 min at ambient temperature. Determination of hRf values by densitometry. Linear relationships were obtained between the RM values of the fat-soluble vitamins and the volume fraction of methanol in the mobile phase.

J. Planar Chromatogr. 22, 145-155 (2009). TLC of candesartan, eprosartan, telmisartan, losartan, and valsartan on RP-8 and RP-18 with mobile phases comprising 3:7 mixtures of phosphate buffer of different pH (2-8) and one of three modifiers, acetonitrile, methanol, or tetrahydrofuran, in horizontal chambers at ambient temperature. Detection under UV 254 nm. Quantitative determination by absorbance measurement. Separation of the five sartans was also achieved by TLC on RP-18 with dimethyl sulfoxide - phosphate buffer (pH 5.0) 4:1.

Chinese J. Modern Appl. Pharm. 25 (1), 66-69 (2008). TLC of Qufu Zhuanggu capsule extracts on silica gel with 1) n-hexane - ethyl acetate 4:1; 2) benzene - ethyl acetate 9:1; 3) chloroform - methanol 19:1; 4) cyclohexane - ethyl acetate 5:2; 5) n-hexane - acetone 3:1. Detection 1) under UV 365 nm; 2) by spraying with 10 % sulfuric acid in ethanol and heating at 105 ºC until the spot were visualized; 3) by treatment with ammonia vapors for 10 min; 4) by spraying with 20 % HClO4 in ethanol. Identification by comparison of the chromatograms with those of the standard psoralen.

Rapid Commun. Mass Spectrom. 23, 2711-2723 (2009). HPTLC in combination with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used for the analysis of complex lipid mixtures. For the separation of lipids one-dimensional HPTLC on silica gel aluminum foil was used with a two-phase mobile phase. The combination with MALDI-MS allowed the identification of 70 distinct lipid species and the analysis of even minor lipid classes from only very small volumes of human plasma (50 µL).