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 %.

J. Sep. Sci. 34, 749-760 (2011). HPTLC of (-)-epicatechin (1), (-)-epicatechin gallate (2), (-)-epigallocatechin gallate (3), caffeine (4), rutin (5), quercetin (6), gallic acid (7), ellagic acid (8), caffeic acid (9), and ferulic acid (10) in the leaves of green tea (Camellia sinensis) and guava (Psidium guajava) on silica gel with toluene – acetone – formic acid 5:4:1 for compounds (1) - (6) and toluene – ethyl acetate – formic acid – methanol 15:15:4:1 for compounds (7) - (10). Quantitative determination by absorbance measurement at 282 nm for compounds (1) - (6) and 285 nm for compounds (7) - (10). The hRf values of compounds (1) - (10) were 49, 37, 26, 60, 8, 66, 49, 34,62 and 70, respectively. Linearity was between 100-350 ng/band for compounds (1) - (5), 66.6-233.2 ng/band for compound (6) and between 50-300 ng/band for compounds (7) - (10). The limits of detection were found to be 60 ng/band for compounds (1) - (3), 30 ng for compounds (4), (5) and (8), 40 ng/band for compound (6), 20 ng/band for compound (7) and 10 ng/band for compounds (9) and (10). The limits of quantification were 100 ng/band for compounds (1) - (3), 60 ng/band for compounds (4) - (7), 30 ng/band for compounds (9) - (10), and 75 ng/band for compound (8). Inter- and intraday precisions were below 1.50 % and 2.84 %, respectively. Recoveries were found in the range of 95-100 %.

Acta Chromatographica 20(3), 423-437 (2008). HPTLC of rupatadine fumarate on silica gel with toluene – methanol – triethylamine 20:5:1. The hRf value was 61. Quantitative determination by absorbance measurement at 264 nm. The linearity was in the range of 400–1400 ng/band (r=0.9992). The limits of detection and quantitation were 67 and 202 ng/band, respectively. Moreover, rupatadine fumarate was subjected to acid and alkaline hydrolysis, oxidation, and photochemical and thermal degradation and underwent degradation under all these conditions. The method proved to be repeatable, selective, and accurate for the analysis of the drug by statistical analysis, and is able to separate the degradation products from the drug.

J. AOAC Int. 93, 754-764 (2010). The review describes analytical methods for drug substances, formulations, and clinical samples analyzed and validated by HPTLC during the period 1996-2009. Procedures, materials, and instrumentation for the different steps in the chromatographic procedure and validation of results are given; application to bulk drugs, formulations, stability studies, biological samples (e.g., urine and plasma), and hydrophobicity studies; and prospects for the future use of HPTLC for drug analysis are described. The sections cover the experimental procedures (sample preparation, stationary phases, mobile phases, application of standards and samples, chromatogram development, detection, documentation of chromatograms, densitometric quantitative analysis), determination of hydrophobicity, confirmation of zone identity, method validation, chiral separations, micropreparative layer chromatography, applications of HPTLC-densitometry, and future prospects for HPTLC in drug analysis. 155 references are reviewed.

J. AOAC Int. 93, 804-810 (2010). HPTLC of rutin on amino phase with ethyl acetate - formic acid - methanol - water 100:9:11:17 at room temperature. Detection by spraying with natural products reagent. Linearity was between 0.95 and 4.78 µg/zone. LOD and LOQ were 330 and 630 ng/zone, respectively. The %RSD for six replicates at three concentration levels was less than 3 %, while the recovery was between 97.3-103.3 %. For the three-dimensional image analysis of chromatograms images were taken from each plate using a HP flatbed scanner at an optical resolution of 300 dpi in normal mode. The pictures were stored in TIFF file format. Evaluation was performed using Melanie 7.0 software. Following automatic detection of the zones the program computed the 3D image of a selected region from the HPTLC plate. The volume of the resulting cone-shaped zone was used as numerical data to construct the calibration curve.

J. Planar Chromatogr. 24, 412-418 (2011). HPTLC of milnacipran hydrochloride on silica gel, prewashed with methanol, with chloroform - methanol - ammonia 64:25:2 in a twin-trough chamber saturated for 20 min. Detection under UV light at 245 and 366 nm. Quantitative determination by absorbance measurement at 220 nm. The hRf value of milnacipran was 45. Linearity was between 500 and 6000 ng/zone. The method precision, intra-day precision, inter-day precision, and different analyst precision (n = 6 each, %RSD), was 1.2, 1.9, 1.6, and 1.9 %, respectively. The mean recovery (n = 3) was 99.2-99.8 % with a % RSD between 0.6-1.7 %.

Chinese J. Ethnomed. Ethnopharm. 1, 55-66 (2011). TLC of the extracts of Baibanting 1) for Gardenia jasminoides Ellis, on silica gel with ethyl acetate - acetone – methanol – water 5:5:1:1, detection under daylight and by spraying with 10 % sulfuric acid in ethanol and heating at 110 ºC; 2) for Cuscuta chinensis Lam, on polyamide phase with methanol - glacial acetic acid - water 4:1:5, detection by spraying with 3 % alumnium chloride in ethanol, evaluation under UV 366 nm; 3) for Malaytea scurfpea fruit, on silica gel with n-hexane - ethyl acetate 4:1, detection by spraying with 10 % KOH in methanol and evaluation under UV 366 nm. Quantification of gardenoside by HPLC. The procedures proved to be simple, accurate, reproducible, robust and suitable for the quality control of the medicine.

J. Planar Chromatogr. 23, 348-352 (2010). TLC of methoxylated flavones G1, G2, G3, G4 (3’,4’,5’-trimethoxyflavone), and G5 on alumina with n-hexane - ethyl acetate 7:3 at ambient temperature with chamber saturation. Detection by visual inspection at 365 nm. The hRf values of G1 (monomethoxyflavone), G2 (monomethoxyflavone), G3, G4 (trimethoxyflavone), and G5 (dimethoxyflavone) were 42, 30, 22, 17, and 12, respectively.