Analytical Chemistry - An Indian Journal 8(1), 77-81 (2009). An HPTLC method is reported for estimation of lupeol and beta-sitosterol in the whole plant powder of Asteracantha longifolia (Acanthaceae). The proposed method was also employed for estimation of beta-sitosterol in herbal formulation containing Asteracantha longifolia. Methanolic extracts of the sample were used for chromatography. HPTLC on silica gel with toluene - ethyl acetate - methanol 75:15:7. Derivatization with Liebermann-Burchard reagent. Densitometric quantification at 366 nm. The concentration of lupeol and beta-sitosterol was 0.162 mg/g and 0.045 mg/g, respectively in the whole plant, while the concentration of beta-sitosterol was 0.039-0.048 mg/g in the formulation. The method was suitable for the quality control of the herbal formulation.

J. AOAC Int. 93, 787-791 (2010). HPTLC of omeprazole on silica gel with chloroform - methanol 9:1 in a twin-trough chamber after saturation for 20 min. Quantitative determination by absorbance measurement at 302 nm. The hRf value of omeprazole was 39. Linearity was between 50 and 3000 ng/band. The intra-day and inter-day precision was 0.4-0.5 and 0.8-0.9 % (n = 2). The recovery was 98.4-99.1 %. LOD and LOQ were 8 and 24 ng/zone, respectively.

J Vet Sci Med Diagn 2(3), 1-3 (2013). HPTLC of neutral lipids on silica gel (HLF plates with 19 scored channels of 9 mm width) prewashed with dichloromethane - methanol 1:1 and heated for 30 min at 120 °C, with petroleum ether - diethyl ether - glacial acetic acid 80:20:1 with chamber saturation. Detection of dark zones on a yellow background after spraying with 5 % ethanolic phosphomolybdic acid reagent. Quantification of triacylglycerols by absorption measurement at 610 nm with polynomial regression via peak area.

PLoS ONE 8(11), e80841 (2013). On silicic acid columns, total ceramides, from methanol – chloroform extracts of mouse tissue (brain, heart, liver) and of cell cultures (astrocytes, oligodendroglia) were purified from other lipids (phospholipids, sphingoid bases, glycosphingolipids, retained on the column) and fractioned using chloroform – acetone – acetic acid 24:1:0.01 followed by chloroform – acetone – acetic acid 18:2:0.01. For the monitoring, TLC of fractions (layer not specified) with chloroform – methanol – acetic acid 190:10:1. After derivatization by iodine vaporization or by spraying with copper sulfate reagent (copper(II) sulfate 20 mM - sulfuric acid 5 % - ammonium molybdate 1 %), lipids are detected as orange or brown-black zones, respectively. The aforesaid fractionation allowed the isolation of hydroxyl-fatty-acyl ceramides, phytoceramides, non-hydroxy-fatty-acyl ceramides and cholesterol (identification by comparison to standards and by GC-MS); their hRf values were between 40 and 80. Quantitative determination by densitometric measurement. This is the first report of phytoceramide identified in vertebrate brain, heart and liver.

J. Food Compos. Anal. 48, 25-33 (2016). In this study 353 samples of different varieties and different commercial products were analyzed by HPTLC and UV absorbance. HPTLC of the acetonic extract of kava powder on silica gel with hexane – dioxane 4:1 without chamber saturation over a distance of 85 mm. Detection under UV 254 nm and 366 nm. Densitometric evaluation and determination of the ratios kavain/total kavalactones (K/KL) at 254 nm and flavokavins/kavalactones (FK/KL) at 366 nm. Derivatization by dipping in anisaldehyde sulfuric acid reagent (10 mL sulfuric acid, 170 mL methanol, 20 mL acetic acid, 1 mL anisaldehyde) and heating at 100 °C for 3 min. The results showed that noble varieties suitable for daily consumption of kava are characterized by high K/KL and low FK/KL.

Food Control 86, 214-223 (2017). HPTLC of epicatechin (1) and proanthocyanidins PAC-A2 (2) and PAC-B2 (3) in cranberry juice on silica gel with dichloromethane – ethyl acetate – formic acid 3:5:1. Detection by spraying with anisaldehyde sulfuric acid reagent, followed by heating at 100 °C for 2 min. Quantitative determination by absorbance measurement at 200 nm. Intermediate precision was below 2 % (n=9). Recovery was between 99.9 and 100.1 % for (1) to (3).

Planta Med. 83, 1097-1102 (2017). The fractionations on a silica gel column (with a gradient of ethyl acetate, methanol and petroleum ether/dichloromethane) of the dichloromethane and methanol extracts of Antidesma ghaesembilla bark were monitored by TLC on silica gel with chloroform – methanol – water – formic acid 290:20:1:1 or 290:50:1:1, respectively. From fractions of the dichloromethane extract, chavibetol, sitostenone, asperphenamate, daucosterol, 5,7-dimethoxy-aristolochic acid II and 10-amino-5,7-dimethoxy-aristolic acid II were later isolated, the last one was detected by Dragendorff reagent. From fractions of the methanol extract, glucosides of aristolic acid and of vanillic acid were isolated and separated by preparative TLC with chloroform – methanol – acetone – formic acid 450:75:25:2. This preparative TLC yielded protocatechuic acid (hRF 51) and a mixture (hRF 14–19), from which a methyl-phloroglucinol glucoside was isolated by gel exclusion chromatography.

J. Planar Chromatogr. 3, 247-250 (1990). TLC of tryptophan on cellulose with 1-butanol - acetic acid - water 4:1:5. Detection by overpressure derivatization (OPD), which is carried out by pressing an absorbent polymeric pad (prewetted with derivatization reagent) on the TLC plate. Relative standard deviations obtained showed that OPD was more reproducible than spraying. Quantification by densitometry (absorbance at 420 and 288 nm after derivatization).