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.

Indian J. Pharm. Sci. 72(2), 249-252 (2010). HPTLC of rosiglitazone on silica gel with methanol - toluene - chloroform - triethyl amine 2:161:1. Caffeine was used as internal standard. The hRf value of rosiglitazone was 31 and of caffeine 52. Densitometric evaluation at 264 nm. The method was linear in the range of 5-50 µg/band with average recovery of 99.8-100.2 %. The method was suitable for content uniformity testing according to USP and could be used for stability studies as well.

J. Planar Chromatogr. 23, 286-288 (2010). TLC of taxol with a stationary-phase gradient whereby parts of different TLC plates were connected by use of a MIGAS device. Separated taxol-containing zones were developed with methanol over 1 cm and thus moved to another plate. The lipophilic substance zone was cut out after separation of the sample on a silica gel plate with n-heptane - ethyl acetate 1:1. Further separation of taxol from accompanying hydrophilic substances was carried out on HPTLC RP-18W with methanol - water 4:1. The taxol-containing fraction was finally separated on silica gel with chloroform - acetone 3:1 in a horizontal chamber at constant temperature (30 +/- 1°C) and humidity (35 +/- 1 %). Detection under UV 254 and 366 nm. Quantitative determination by densitometry at 220 nm. The precision (n = 7) was 0.63 % and the repeatability (n = 7) 3.35 %. The limit of detection and quantification was 0.50 and 1.00 µg/zone, respectively; the correlation coefficient from linear regression was >0.98, and the linear calibration range was 1 - 10 µg/zone.

J. Chromatogr. A 1217(34), 5470-5476 (2010). Description of a combination method using high-speed counter-current chromatography and TLC as an antioxidant assay to separate antioxidant components from the fruits of Psoralea corylifolia by dipping in a ethanolic DPPH radical solution (2.54 mM) for autography. Bands with the DPPH scavenging activity were observed as white yellow bands on a purple background. High-speed counter-current chromatography of five flavonoids and three coumarins from the fruits of P. corylifolia with n-hexane - ethyl acetate - methanol - water 10:11:13:1. Preparative TLC for clean-up improves the substance yield from the fruits.

Rapid Commun. Mass Spectrom. 25, 2201-2208 (2011). HPTLC of an equimolar mixture of malto-oligosaccharides, derivatized with p-aminobenzoic acid, on silica gel with acetonitrile – water – acetic acid 8:2:1. Quantitative determination by fluorescence measurement at 366 nm. The relative molar composition of the oligomers, determined by HPTLC, was used as a reference data for mass spectrometric analyses. For both electrospray ionization and matrix-assisted laser desorption/ionization methods, the instrumental parameters significantly influence the signal intensities and areas.

Int. J. Pharma. Sci. 2(1), 390-394 (2010). TLC of salbutamol sulphate (SS), ambroxol hydrochloride (AH), and theophylline (THE) in a ternary fixed dose formulation on hand made silica gel plates with methanol – n-hexane 21:9. The hRf values were 25 for SS, 72 for THE and 89 for AH. Detection under UV 254 nm and by exposure to iodine vapors. The bands of the respective compounds were scraped off and quantified by spectrophotometry.

62nd Indian Pharmaceutical Congress Abstract No. F-245 (2010). TLC of amlodipine besylate and nebivolol hydrochloride on silica gel with methylene chloride – methanol – 25 % ammonia 17:2:1. Both drugs were well resolved with hRf values of 19 and 41 for amlodipine besylate and nebivolol hydrochloride respectively. Quantitative determination by absorbance measurement at 285 nm. The method was linear in the range of 200-600 ng/band for both drugs. Recovery was 99.9-102.1 %.

Acta Chromatographica 22 (3), 481-489 (2010). HPTLC on silica gel with toluene – ethyl acetate – methanol – formic acid 8:10:5:2. The hRf values were 22, 19, and 81 for sennosides A and B and kaempferol, respectively. Quantification by densitometry at 270 nm. The recovery of sennosides A and B and kaempferol from Cassia fistula extract were 98.0, 98.7, and 99.1 %, respectively. The linearity was in the range of 100–400 ng/band. Instrument precision was in the range of 1.03-1.33 % and method precision in the range of 1.3-1.8 %.