collected from different phyto-geographical zones of India. J. Liq. Chromatogr. Relat. Technol. 36, 1810-1821 (2013). HPTLC of protodioscin (1) and prototribestin (2) in fruits of Tribulus terrestris on silica gel with n-butanol - glacial acetic acid - water 40:3:10. Quantitative determination by absorbance measurement at 366 nm. The hRf values of (1) and (2) were 41 and 39, respectively. Linearity was in the range of 100-1000 ng/zone for both (1) and (2). LOD and LOQ were 40 and 100 ng/zone for (1) and 35 and 100 ng/zone for (2). Intermediate precision was below 1.0 %. Recovery ranged 98.0-103.0 % for (1) and 99.1-101.9 % for (2).

J. Liq. Chromatogr. Relat. Technol. 36, 2348-2362 (2013). Nonmicellar 2(1) and micellar (2) TLC of 35 model compounds with different functional groups on silica gel, RP-18 and CN phase with modifiers in hexane and water for (1) and on RP-8 with three surfactants, namely cetyltrimetylammoniumbromide, sodium dodecylsulfate, and Triton-X100 dissolved in water above CMC for (2). A principal component analysis (PCA) allowed for a molecular structure-retention relationship study.

J. Planar Chromatogr. 26, 452-454 (2013). Optimization of temperature and duration required for detection of terpene trilactones. TLC of ginkgolides A, B and C and bilobalide on silica gel with ethyl acetate - hexane 9:1. Detection by spraying with acetic anhydride followed by heating at 80, 100, 120 and 140 ºC. The formation of alpha, beta-unsaturated gamma-lactone from ginkgolides was detected even at low temperatures for a respective heating time.

J. Liq. Chromatogr. Relat. Technol. 37, 941-950 (2014). HPTLC of ibuprofen (1) and famotidine (2) on silica gel with methanol - ethyl acetate - hexane - ammonia 4:12:2:1. Quantitative determination by absorbance measurement at 264 nm. The hRf values for (1) and (2) were 41 and 69, respectively. Linearity was in the range of 320-9600 ng/zone for (1) and 10-300 ng/zone for (2). LOD and LOQ were 104 and 316 µg/mL for (1) and 3 and 10 µg/mL for (2). Recoveries (by standard addition) were in the range of 100-101 % for both (1) and (2). Intermediate intra- and inter-day precision was below 2 % (n=3).

J. Planar Chromatogr. 26, 209-214 (2013). HPTLC of pioglitazone hydrochloride on silica gel with chloroform - methanol 10:1. Detection by spraying with 0.5 % o-phthalaldehyde in ethanol, followed by heating at 70 ºC for 15 min. Quantitative determination by scanning with a flatbed scanner and a gel analysis software. Linearity was in the range of 200-3000 ng/zone. LOD and LOQ were 65 and 197 ng/zone, respectively. Recovery was in the range of 98-102 %. Intermediate/interday/intra-day precision was below 2 %.

J. Planar Chromatogr. 26, 417-420 (2013). HPTLC of gamma-amino butyric acid (GABA) in mice brain tissue on silica gel with n-butanol - glacial acetic acid - water 65:18:28. Detection by dipping in 0.2 % ninhydrin solution, followed by heating at 65 ºC for 3 min. Quantitative determination by absorbance measurement at 480 nm. Linearity was between 100 and 1000 ng/zone. LOD and LOQ were 50 and 151 ng/zone. Recovery (by standard addition) was found to be 65-78.5 %. Intra- and inter-day precision values were below 7.7 %.

J. Liq. Chromatogr. Relat. Technol. 37, 2892-2914 (2014). Study of the background mass signals derived from different solvents either used for prewashing or chromatography that may interfere in HPTLC-MS using the elution head-based TLC-MS Interface. Pre-washing of plates with methanol – water 3:1 reduced background signals to a minimum, but also special plates for MS are suited (plates of specified MS quality). The results showed that acidic solvents can cause intense background signals due to acid adduct cluster formations. The fluorescence indicator did not impact the mass spectra. It was shown that subtraction of background spectra (at a comparable migration distance) from the analyte mass spectrum is a helpful tool, especially in the case of cluster formation. Recommendations for general plate handling for use in TLC/HPTLC-MS were provided.

Rev. Bras. Farmacogn. 23, 802-810 (2013). HPTLC of quercetin (1) and gallic acid (2) in Adiantum capillus-veneris on silica gel with toluene - ethyl acetate - formic acid 5:4:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) and (2) were 53 and 84. Linearity was in the range of 200-1600 ng/zone for both (1) and (2).