Planta med. 68, 435-439 (2002). TLC of 10-hydroxy-N(a)-demethyl-19,20-dehydroraumacline on silica gel with ethyl acetate - methanol - water - ammonia 70:20:10:1, chloroform - methanol - water - ammonia 50:45:5:1 and 50:40:10:1. Detection under UV light at 254 nm and after spraying with cericammonium sulfate (CAS) reagent.

J. Chromatogr. Sci. 43 (4), 183-194 (2005). HPTLC of selected alkaloid standards on RP18 W layer with various aqueous eluents containing an organic modifier and pH 3 buffer to suppress silanol ionization or an organic modifier and pH 8 buffer to suppress alkaloid ionization. Anionic ion pairs such as sodium dodecyl sulfate, octane-1-sulfonic acid sodium salt, pentane-1-sulfonic acid sodium salt, and bis(2-ethylhexyl)ortho-phosphoric acid are used to improve peak shape, efficiency, and selectivity. Amines (e.g., diethylamine, triethylamine, and tetrabutylamonium chloride) are incorporated into mobile phases to block surface silanols. The effect of chromatographic conditions on the separation of the investigated alkaloids is analyzed by the comparison of particular densitograms, asymmetry factor, or theoretical plate number. The best efficiency, peak symmetry, and separation selectivity of the investigated compounds is obtained through the addition of amine (especially diethylamine) to the mobile phases.

Part II. Connection with RP18 and silica plates. J. Chromatogr. Sci. 46 (4), 291-297 (2008). Optimization of the one-dimensional TLC of alkaloid standards on cyano phase, RP-18W, and silica gel with various eluents containing silanol blockers (besides diluent and modifier), such as diethyl amine or ammonia. Separation of alkaloid mixtures with the most selective system (e.g. methanol - water 4:1 in the first direction and methanol - acetone - diisopropylether - diethylamine 15:15:69:1 in the second direction) with an adsorbent gradient method. Alkaloids or plant extracts of Chelidonium majus, Fumaria officinalis, or Glaucium flavum were chromatographed in the first system, the plates were connected with the plate pre-coated with various adsorbents, and partly separated fractions were transferred to the second layer and developed in a second system. Cyano - silica - RP-18W and cyano - silica - silica were used as the connected layers. The alkaloids were identified based on the Rf values of standards, and by comparison of UV spectra obtained by densitometry with a diode array detector.

Rapid Commun. Mass Spectrom. 24, 1305-1311 (2010). HPTLC of salvinorin A (1), salvinorin C (2), divinatorin B (3), and salvinorin B (4) in the leaves of Salvia divinorium on silica gel with methyl tert-butyl ether – hexane 3:1 as mobile phase. Detection by desorption electrospray ionization multi-stage tandem mass spectrometry (TLC/DESI-MS). The hRf were 49, 64, 85, and 95 for compounds (1) - (4), respectively. The use of a simple HPTLC protocol in combination with DESI-MS allowed for improved detection of different species of salvinorin in the leaf extracts.

J. Liq. Chromatogr. Relat. Technol. 38, 1088-1093 (2015). HPTLC of tramadol hydrochloride in pharmaceutical formulation on silica gel with ethyl acetate - methanol - ammonia 90:8:5. Quantitative determination by absorbance measurement at 271 nm. The hRF value of tramadol hydrochloride was 64. Linearity was in the range of 1000-6000 ng/zone. Intra-day and inter-day precisions were below 2 % (n=3). Mean recoveries were found to be around 100 %.

Part II: Remijia ferruginea. Rev. Bras. Farmacogn. 27, 153-157 (2017). HPTLC fingerprint of Remijia ferruginea on silica gel with ethyl acetate – toluene – formic acid – water 12:4:4:3. Detection by spraying with natural product reagent, followed by PEG reagent. The hRF values for rutin, chlorogenic acid and cinchonine were 50, 60 and 65, respectively.

Coll. czechoslov. chem. comm. 47, 1641-1644 (1982). TLC of ergoline on silica with a) chloroform - ethanol - triethylamine 92:6:2, b) benzene - dioxane - ethanol -NH3 48:38:10:5. Detection by spraying with 20 % p-toluenesulfonic acid in methanol and heating, or by UV 254 and 366 nm.

Planta med. 47, 87-89 (1983). TLC of cycleanine N-oxide on silica with ethyl acetate - isopropanol - NH3 25 % 9:7:2. Detection by UV, iodoplatinate reagent or with 0.2 M FeCl3 in 35 % HClO4 and heating, also mixture of HNO3 and H2SO4.