62nd Indian Pharmaceutical Congress Abstract No. F-256 (2010). TLC of amlodipine besylate and enalapril maleate on silica gel with toluene – isopropanol – glacial acetic acid – methanol 50:20:6:5. The hRf values were 15 and 23 for amlodipine besylate and enalapril maleate, respectively. Quantitative determination by absorbance measurement at 223 nm.

Chinese J. Food R & D, Test & Anal. 31 (10), 134-138 (2010). TLC of chlorogenic acid on silica gel with ethyl acetate – water – formic acid 17:2:2. Detection by spraying with 2 % FeCl – 1 % KFe(CN) 4:1.

Acta Chromatographica 22 (2), 297-305 (2010). Description of a simple, precise, and accurate method for simultaneous quantification of aspirin, atorvastatin calcium and clopidogrel bisulphate by HPTLC on silica gel with toluene – methanol - formic acid 65:35:1. The hRf values were 26, 47, and 78 for aspirin, atorvastatin calcium, and clopidogrel bisulphate, respectively. Quantification by densitometry at 254 nm. The precision intra-day and inter-day was in the ranges of 0.2–0.7 %RSD and 0.5–1.0 %RSD for aspirin, 0.4–0.9 %RSD and 0.4–0.6 %RSD for atorvastatin calcium, and 0.3–0.7 %RSD and 0.4–0.9 %RSD for clopidogrel bisulphate.

J. of Guangzhou Chem. Engin. 39(1), 144-145 (2011). A course on the technology of TLC/bioautography applied for the analysis of TCM was set-up to enhance students’ understanding of theoretical knowledge and to train and improve the interest and skill of students in chemical experiments. Demonstration of the TLC analysis of rutin and quercetin in Flos Sophorae on silica gel with ethyl acetate – formic acid – water 8:1:1. Detection under UV 254 nm and 366 nm, and by immersing into a solution of 1,1-diphenyl-2-picrylhydrazyl in ethanol (DPPH radical reagent). The result of this practice was satisfactory, and the course proved to be a good example to utilize the modern technology in the experimental teaching.

J. of Chromatogr. A 1218 (37), 6540-6547 (2011). New approach and application of highly automated planar chromatographic tools for powerful clean-up, called high-throughput planar solid phase extraction (HTpSPE), which is indispensable for preventing matrix effects in multi-residue analysis of pesticides in food by liquid and gas chromatography coupled to mass spectrometry, employing TLC to completely separate pesticides from matrix compounds and to focus them into a sharp zone, followed by extraction of the target zone by the TLC-MS interface, thus resulting in extracts nearly free of interference and free of matrix effects, as shown for seven chemically representative pesticides in four different matrices (apples, cucumbers, red grapes, tomatoes), and completion of clean-up of one sample in a manner of minutes. Regarding the clean-up step, quantification by LC–MS with mean recovery (against solvent standards) of 90–104% and relative standard deviations of 0.3–4.1% (n = 5) for two spiking levels of 0.1 and 0.5 mg/kg.

J. of Chromatogr. A 1218 (24), 3811-3815 (2011). HPTLC of sugars in bio-oil fractions on silica gel with acetonitrile - water 4:1, or mixtures of butanol and formic acid, followed by detection with the aniline - diphenylamine - o-phosphoric acid reagent. The method allowed for the separation of the anhydrosugars levoglucosan and cellobiosan, as well as glucose, arabinose, xylose and cellobiose without the need of pre-treatment and pre-derivatization of samples. Volatile compounds present in bio-oil did not interfere with sugar analysis, and the detrimental effect of the complex bio-oil matrix on columns and detector lifetime is avoided by using disposable HPTLC plates. It was found that the concentrations of levoglucosan and cellobiosan in bio-oil samples obtained from Pinus radiata sawdust were ranged between 1.3-2.3 % and 1.0-2.0 % respectively, while a higher levoglucosan concentration was in a bio-oil sample obtained from native wood.

J. Planar Chromatogr. 24, 136-139 (2011). HPTLC of ethanolic extracts of plant material and betaine on silica gel, prewashed with methanol, with methanol - water 9:1 in a twin-trough chamber saturated for 30 min. Detection under UV light at 254 and 366 nm and by spraying with Dragendorff’s reagent or with sulfuric acid reagent followed by heating at 120 °C for 10 min (Dragendorff’s reagent) or at 110 °C until the intensity of the fluorescent zones reached a maximum (sulfuric acid). Quantitative determination by densitometry at 550 nm. The calibration range was between 4 and 30 µg/band. LOD and LOQ was 1 and 4 µg/band, respectively. The repeatability (n = 6) was 1.7 %. The recovery was between 99.1-101.9 %. The inter-day and intra-day precision (n = 3) was between 1.1- 2.2 % and 1.2-2.2 %, respectively.

J. Planar Chromatogr. 24, 99-104 (2011). TLC of candesartan and losartan on silica gel with 1,4-dioxane - hexane - 99 % formic acid 50:50:1. Quantitative determination by densitometry at 258 nm for candesartan and at 243 nm for losartan, videoscanning at 254 nm for both drugs. The hRf value for candesartan was 47 and for losartan 35. Linearity was between 0.2 and 1.4 µg/band for both drugs with correlation coefficients of 0.9997 and 0.9981 for candesartan, and 0.9986 and 0.9982 for losartan, for densitometry and videoscanning, respectively. Robustness (%RSD, peak area) was less than 1.9 and 0.8 % for candesartan, and 2.2 and 0.9 % for losartan in densitometry and videoscanning, respectively. The repeatability and intermediate precision (%RSD, two lowest amounts) were less than 3.6 and 4.7 % for candesartan and less than 4.7 and 5.3 % for losartan. Mean recoveries for candesartan were 103.8-104.9 % for densitometry and 99.2-100.7 % for videoscanning; for losartan the respective values were 100.8-105.4 % and 98.6-99.2 %.