Eurasian J. Anal. Chem. 5(1), 25-27 (2010). An HPTLC method is reported for estimation of levodopa in seeds of Mucuna pruriens and its herbal formulation. HPTLC on silica gel with n-butanol - glacial acetic acid - water 5:1:4. Densitometric evaluation at 280 nm. The hRf value of levodopa was 39. The method was linear in the range of 100-1000 ng/band. The method is suitable for estimation of levodopa in herbal formulation.

Journal of Pharmacy Research 2(1), 189-195 (2009). A validated HPTLC method has been developed for simultaneous estimation of valdecoxib and tizanidine in dosage form. HPTLC on silica gel with toluene - methanol - ethyl acetate 2:2:1. The compounds were well separated as compact bands. The method was linear in the range of 10-100 ng/band for tizanidine and 100-1000 ng/band for valdecoxib. The recovery was in the range of 99.3-101.2 %. Densitometric quantification at 254 nm. The method is suitable for quality control of combined dosage form.

J. Planar Chromatogr. 23, 396-399 (2010). TLC of 8 newly synthesized N-phenyltrichloroacetamides on RP-18 W with micellar-organic solutions composed of 0.02, 0.04, or 0.06 M Brij 35 (2-dodecoxyethanol, a nonionic surfactant) and tetrahydrofuran 4:1 in saturated sandwich chambers. Detection under UV 254 nm. According to the results obtained from the OPLC studies, especially log km values are excellent descriptors of the lipophilicity of the compounds.

J. AOAC Int. 93, 1222-1227 (2010). HPTLC of rosuvastatin (ROS) and ezetimibe (EZE) on silica gel with n-butyl-acetate - chloroform - glacial acetic acid 1:8:1 with chamber saturation for 30 min. Quantitative determination by densitometry at 245 nm. The hRf value of ROS was 30 and of EZE 58. The linearity for ROS and EZE was 0.1 to 0.9 µg/zone.The intraday and interday precision was 0.62 % and 0.73 % for ROS and 0.59 % and 0.69 % for EZE (n=3). The LOD values for ROS and EZE were found to be 0.04 and 0.07 µg/spot, respectively, and their LOQ values were 0.07 and 0.1 µg/spot, respectively. The recovery study results ranged from 98 to 101 % for ROS and EZE.

Trends in Chromatography 6, 1-10 (2010). Review on TLC, HPTLC and other chromatographic methods for the analys of selected metabolite classes such as neutral and polar lipids, amino acids, carbohydrates, carboxylic acids, lipophilic pigments, and purine bases in estivating pulmonate snails.

CBS 106, 5-6 (2011). HPTLC on 1) ProteoChrom silica gel with 2-butanol – pyridine – ammonia 25 % – water 39:34:10:26; on 2) ProteoChrom cellulose with 2-butanol – pyridine – acetic acid – water 15:10:3:12 by two-dimensional development and on 3) silica gel with the developing solvent from 2). Detection by spraying with ninhydrin, fluorescamine, or triethylamine reagent. Evaluation under daylight and UV 366 nm. Detection by mass spectrometry by scanning the plate with a self modified desorption electrospray beam. In one-dimensional HPTLC up to 20 bands can be separated. By two-dimensional separation this number can be increased. Particularly suited are cellulose HPTLC plates.

Acta Chromatographica 20(4), 709-719 (2008). HPTLC of trigonelline and 4-hydroxyisoleucine from Fenugreek seeds (Trigonella foenum-graceum) on silica gel with n–butanol – methanol – acetic acid – water 8:3:2:2. Detection by spraying with ninhydrin reagent. Quantification by densitometry at 266 nm for trigonelline, and at 395 nm for 4-hydroxyisoleucine. The linearity was in the range of 100-1000 ng/band for trigonelline and 50-500 ng/band for 4-hydroxyisoleucine, respectively, with r=0.9992 and 0.9986 respectively. The average recovery at three different levels was 99.4 % for trigonelline and 99.1 % for 4-hydroxyisoleucine.

Analytical Chemistry, An Indian Journal 9(3) (2010). HPTLC of a racemic mixture of oxybutynin chloride on chiral phase with toluene – acetone – methanol 8:1:1. Both enantiomers were well separated with hRf values of 47 and 63. The identity of the isomers was established by on-line UV, NMR and MS data. The method was validated using NP-TLC and the same mobile phase. The method was linear in the range of 50-350 µg/band with a recovery of 98.2-101.7 %.