Chromatographia 70 (1-2), 309-313 (2009). TLC on silica gel with acetonitrile - methanol - dichloromethane 2:1:2. The hRf value of dutasteride was 64. Separation of dutasteride from its degradation products (produced by acid and alkali hydrolysis, oxidation, photo degradation, dry and wet heat treatment) was good. Quantitative determination by absorbance measurement at 244 nm. Linearity was in the range of 100 - 600 ng/band and the correlation coefficient was 0.9943 (via peak area) The limit of detection and quantitation was 7 and 23 ng/band.

Correlation of lipophilicity with affinity for alpha-adrenoceptors. J. Planar Chromatogr. 22, 141-144 (2009). Determination of the relative lipophilicity of 14 1-substituted pyrrolidin-2-one by TLC on RP-18 with mixtures of acetonitrile and pH 7.0 Tris buffer with volume fractions of acetonitrile between 20 and 80 %, with chamber saturation for 2 h. Detection under UV light. Retention data obtained by this method were exponentially dependent on acetonitrile concentration and enabled estimation of the relative lipophilicity corresponding to pH 7.0 Tris buffer as mobile phase.

J. Chromatogr. A 1216 (11), 2150-2155 (2009). Chaihu roots (Bupleuri radix), roots of Bupleurum chinense and Bupleurum scorzonerifolium are monographed in the Chinese Pharmacopoeia. Evaluation of the quality of 33 lots of authenticated Chaihu samples versus 31 lots of commercial samples by HPLC-ELSD and HPTLC analysis of the principal bioactive components (saikosaponins). Data acquired from HPLC fingerprints and HPTLC fluorescent images was analyzed by chemometrics for similarity and pattern recognition, including artificial neural networks, k-nearest neighbor (k-NN) and an expert’s panel. The k-NN classifier showed good performance with sufficient flexibility for processing HPTLC fingerprint images. These images were otherwise not easily dealt with by other algorithms due to the shift of hRf values and varying hue/saturation of the band colors between different TLC plates. The two chromatographic fingerprint methods are complementary measures for quality control. Chaihu roots from different species of the genus Bupleurum could readily be distinguished from each other. Commercial samples of Chaihu can easily be classified by investigating the content of major saikosaponins.

Rapid Commun. Mass Spectrom. 23, 2597-2604 (2009). RP-TLC of pharmaceutical formulations containing paracetamol, ephedrine, codeine, and caffeine on hydrocarbon-impregnated silica with methanol - water 1:1. Detection by desorption electrospray ionization (DESI) combined with ion mobility mass spectrometry (IM-MS). The limit of detection was 9, 16, 34, 239 and 225 µg/cm2 for codeine, caffeine, ephedrine and paracetamol, respectively.

Photoreactivity of biologically active compounds. Pharmazie 64, 428-435 (2009). TLC of riboflavin and lumichrome (7,8-dimethylbenzo[g]pteridine-2,4-(1H,3H)-dione) on silica gel with acetic acid - acetone - methanol - benzene 1:1:4:14 Detection under visible light and UV 254 and 366 nm.

J. Chinese Trad. & Herb. Drugs 40 (8), 1249-1252 (2009). TLC of extracts of the TCM drug on silica gel with 1) methanol - acetic acid - water 18:1:4; 2) petroleum ether (60-90 °C) - ethyl acetate 1:1; 3) toluene - ethyl acetate - methanol 5:5:3; 4) petroleum ether (60-90 °C) - ethyl acetate - formic acid 15:5:1. Detection 1) by spraying with potassium iodobismuthate reagent; 2) under UV 254 nm; 3) by spraying with 5 % AlCl3 in ethanol and evaluation under UV 365 nm.

J. Chinese Trad. Patent Med. 30 (12), Supl. 4-6 (2008). TLC of the TCM drug extracts on silica gel with 1) dichloromethane - ethyl acetate - methanol - water 15:40:22:10; 2) petroleum ether (60-90 °C) - diethyl ether 3:2; 3) petroleum ether (60-90 °C) - ethyl acetate 25:2; 4) n-butanol - acetic acid - water 4:1:2; 5) chloroform - diethyl ether 1:1. Detection 1) by spraying with 10 % sulfuric acid in ethanol followed by heating at 105 °C until coloration; 2) under UV 365 nm; 3) under UV 254 nm.

J. Chromatogr. A 1217 (23), 4655-4662 (2010). Development and application of electrospun glassy carbon nanofibers for ultra-thin layer chromatography (UTLC). The carbon nanofiber stationary phase was created through electrospinning and pyrolysis of SU-8 2100 photoresist, which resulted in glassy carbon nanofibers with diameters of 200-350 nm that form a mat structure with a thickness of 15 µm. The chromatographic properties of UTLC devices produced from pyrolyzed SU-8 heated to temperatures of 600, 800, and 1000 °C were investigated. By use of Raman spectroscopy and scanning electron microscopy the physical and molecular structure of the nanofibers at each temperature was determined. The carbon UTLC devices were suitable for the analysis various dye mixtures and also allowed separation of three FITC-labeled essential amino acids (lysine, threonine, phenylalanine). The electrospun glassy carbon UTLC plates showed good retention properties, plate number values above 10000, and physical and chemical robustness for a range of mobile phases.