J. Planar Chromatogr. 23, 406-410 (2010). TLC and OPLC of essential oil of thyme (thymol, carvacrol, and linalool as standards) on silica gel with chloroform (previously extracted with a 0.1 % aqueous solution of sodium hydrogen carbonate and dried on sodium sulfate to eliminate the stabilizer amylene, free hydrochloric acid, and chlorine) in an unsaturated chamber. Detection at 254 nm, by spraying with vanillin - sulfuric acid reagent (50 mg vanillin with 12 mL ethanol and 200 mL 98 % sulfuric acid) and heating to 70 °C for 10 min, and by use of the BioArena system. Quantitative determination by densitometry at 275 and 600 nm (dual-wavelength measurement).

International Journal of Green Pharmacy 3 (1), 47-17 (2009). HPTLC of caffeine on silica gel with ethyl acetate - methanol 9:1. Densitometric quantification at 274 nm. The method was linear in the range of 2-14 µg/band. The sample extracted with 5 % diethyl amine in water gave the maximum yield of caffeine (2.1 %). The proposed chromatography gave the best resolution with caffeine at an hRf value of 40. The method can be used for quality control of tea samples in respect of caffeine contents.

Phytochem. Anal. 21, 556-560 (2010). HPTLC of betulinic acid in the rhizomes of Nelumbo nucifera on silica gel with chloroform - methanol - formic acid 49:1:1. Detection by spraying with anisaldehyde - acetic acid - methanol - sulfuric acid 5:100:850:50 and drying at 50 °C for 10 min. Quantitative determination by absorbance measurement at 420 nm. The hRf of betulinic acid was 30. Linearity was between 2 and 10 µg/zone. Detection and quantification limits were 0.4 and 2.30 µg, respectively. The intra-day and inter-day precisions were 0.4 % and 0.3 % (n=3) respectively. Recovery (by standard addition) was 98.4 %.

62nd Indian Pharmaceutical Congress Abstract No. F-259 (2010). Health drinks usually contain several phytopharmaceuticals with immunomodulatory and antioxidant activities. TLC of gallic acid on silica gel with toluene – ethyl acetate – methanol – formic acid 15:15:1:4. The gallic acid content was established and the identity of the gallic acid zone in sample and standard was confirmed by UV spectra comparison.

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 %.

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.

Planta Med. 75, 1000 (2009). TLC and HPTLC of Mezereon (Daphne mezereum) bark extracts and scopoletin, umbelliferone, mezerein, and daphnetoxin on silica gel with various mobile phases containing toluene, ethyl acetate, and formic acid at different proportions. Detection under UV 254 and 366 nm and visible light. The applied procedure may be proposed for an updated and optimized TLC identification test of the homeopathic monograph of Daphne mezereum L.

J. Planar Chromatogr. 24, 66-71 (2011). HPTLC of extracts of Stresroak premix and gallic acid (1), mangiferin (2), and withanolide A (3) as standards on silica gel with A) ethyl acetate - formic acid - acetic acid - water 100:11:11:27, for (1) and (2), and B) chloroform - methanol 9:1 for (2) in a twin trough chamber. Quantitative determination by absorbance measurement at 280 nm for (1), 330 nm for (2), and 225 nm for (3). The hRf values of (1), (2) and (3) were 76, 29, and 48, respectively. The average recoveries were 100.4 % (1), 99.3 % (2) and 98.0 % (3). The linear concentration range was 50-150 ppm for (1), and 40-100 ppm for (2) and (3). The LOD, defined as the amount of compound required to produce a signal at least three times the noise level, for gallic acid, mangiferin, and withanolide A was 80, 110, and 200 ng for (1), (2), and (3), respectively. The LOQ was 20, 27, and 38 µg, respectively.