Phytochem. Anal. 17, 164-166 (2006). HPTLC of gymnemagenin on silica gel with chloroform - methanol 9:1. Quantitative determination by absorbance measurement at 290 nm. Linearity of the determination of gymnemagenin was observed in the range of 4 - 10 µg. The average percentage recovery from an extract was 99.1 %, the content of leaves was 1.61 % (dry weight).

J. Liq. Chromatogr. & Relat. Technol. 30, 701-728 (2007). TLC on silica gel, RP phase, and cellulose as a common analytical method for screening, separation, and preliminary identification of hydrophilic vitamins (vitamin C and B complex: B1, B2, B3, B5, B6, B9, B12, and vitamin H), and lipophilic vitamins (vitamin A, E, D, and K) in tablets, food, and body fluids.

J. Chinese Trad. Patent Med. (Zhongchengyao) 29 (2), 217 0 221 (2007). TLC of the extracts of Anxinkang dropping pills on silica gel with 1) chloroform - methanol - ammonia 25:3:1; 2) petroleum ether (60 - 90 ºC) - ethyl acetate 20:1; 3) ethyl acetate - acetone - methanol 5:5:1. Detection 1) by spraying with 10 % potassium iodobismuthate solution; 2) by spraying with 5 % p-diethylaminobenzaldehyde in 10 % H2SO4 in ethanol, and heating at 105 °C for 10 min; 3) by spraying with 10 % H2SO4 in ethanol and heating at 105 °C. Identification by comparison with standard.

J. Chinese Trad. Patent Med. (Zhongchengyao), 29 (2), 235-237 (2007) TLC of the extracts of the title Chinese traditional patent medicine on silica gel with 1) toluene - ethyl acetate 15:1; 2) chloroform - methanol - concentrated ammonia water 20:5:0.5. Detection 1) under UV 365 nm; 2) 5% nynhydrin solution and heating at 105 ºC till the spots visualized. Identification by standard comparison, also by GC fingerprint techniques. Quantification of strychnine by HPLC. Discussion of application of the procedures for the quality control of the medicine.

J. Chromatogr. A 1043 (1-2), 243-251 (2007). Presentation of the coupling of planar chromatography with direct analysis in real time time-of-flight mass spectrometry (DART-TOF-MS) for the first time. By cutting the plate within a track led to substance zones positioned on the plate edge, the interested zones were directly introduced into the DART gas stream to obtain the mass signals instantaneously within seconds, giving the detectability in the very low ng/zone-range on the example of isopropylthioxanthone. The coupling was perfectly suited for identification and qualitative purposes, but for quantification of results the analytical response and the repeatability were strongly dependent from proper manual positioning of the HPTLC plate into the excited-state gas stream of the ion source. By using stable isotope-labeled standards the drawback can be overcome demonstrated with the example of caffeine, and the analytical response (r2 of 0.9892) and repeatability (RSD < ±5.4%, n = 6) were improved to a high extent. The spatial resolution by an in-house-built plate holder system was shown to be better than 3 mm; the decay of the signal was observed. Comparison of the efficacy of this new coupling to a plunger-based extraction device for HPTLC/electrospray ionization–MS. The detectability of latter showed to be down to the pg/zone-range, e.g. the limit of quantification for isopropylthioxanthone to be 100 pg/zone. The repeatability was comparable (RSD ± 6.7%), however, without the need of internal standard correction, and the analytical response slightly better (r2 of 0.9983). The spatial resolution was 2 mm or 4 mm depending on the plunger head used.

J. Sep. Sci. 30, 2053-2058 (2007). HPTLC of umbelliferone (1), psoralen (2), and eugenol (3) in the dried fruit pulp of Aegle marmelos and in the fruit of Trachyspermum ammi and Foeniculam vulgare on silica gel with toluene – methanol 19:1. Quantitative determination by absorbance measurement at 331 nm for (1), 304 nm for (2), and 280 nm for (3). The hRf values were 30, 58, and 70 for (1), (2), and (3), respectively. Linearity was between 1 and 5 ng/zone, 16 and 96 ng/zone, and 200 and 1000 ng/zone for (1), (2), and (3), respectively. The limits of detection and quantification were 0.8 and 1.2 ng/zone for (1), 8 and 16 ng/zone for (2), 60 and 150 ng/zone for (3), respectively. Recoveries were 98.9 %, 100.1 %, and 99.3 %, for (1), (2), and (3) respectively.

J. Sep. Sci. 30, 1893-1898 (2007). HPTLC of L-DOPA in tablets on silica gel with acetone – chloroform – n-butanol – acetic acid glacial – water 12:8:8:8:7. Quantitative determination by absorbance measurement at 497 nm. The hRf value of L-DOPA was 37 and selectivity regarding matrix was given. Linearity was between 100 and 500 ng/µL. The intra-assay variation was between 0.26 and 0.65 % and inter-assay variation was between 0.52 and 2.04 %. The limits of detection and quantification were 1 and 3 ng/µL, respectively. No significant difference was found between this method and the official HPLC method.

CBS 98, 2-4 (2007). HPTLC of amino-3-propan-1-ol, a degradation product of dexpanthenol, on silica gel with ethanol - water - acetic acid 16:3:1. To the mobile phase the derivatization reagent was added, i.e. 0.5 g ninhydrin were dissolved in 100 mL solvent mixture. Development in the horizontal developing chamber from both plate sides over 40 mm. Detection by heating at 105 °C for 5 min. Quantitative determination by absorbance measurement at 486 nm. The hRf value of amino-propanol was 50. The mean repeatability was 4.9 % at 5 different concentration levels. The relative standard deviation of the intermediate precision (n=9) was 5.7 %. The limit of detection and quantification was 4.5 µg/mL and 15 µg/mL, respectively (related to the application volume of 2 µL). Recovery (n=15) was 102 %.