Part II. TLC of some phenols. J. Planar Chromatogr. 17, 9-13 (2004). TLC separation of some phenolic compounds (phloroglucinol, 2-aminophenol, 4-hydroxybenzaldehyde, 4-methoxyphenol, salicylic acid, phenol, 4-tert-butylphenol, 2,4-dichlorophenol, 2,6-dimethylphenol) on CN-phases, silica gel and polyacrylonitrile with 14 different mobile phases at ambient temperature in a HPTLC horizontal developing chamber. Detection by spraying with 0.05 % fluorescein solution in ethanol and subsequent exposure to UV light at 366 nm.

J. Planar Chromatogr. 21, 205-208 (2008). TLC of phenol and its methyl derivatives on RP-2, RP-8, RP-18, cyano phase, and DIOL phase with methanol - water, ethanol - water, n-propanol - water, acetonitrile - water, and acetone - water in different volume proportions (100:0, 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, and 65:35), 0.1 M acetic acid and 0.1 M sodium acetate in 30 % methanol (pH 5.0), 0.1 M potassium dihydrogen phosphate in 30 % methanol (pH 7.0), and 1 M ammonia in 30 % methanol (pH 11.3) in a saturated chamber. Best results were achieved on RP-2 with 0.1 M acetic acid and 0.1 M sodium acetate in 30 % methanol, 0.1 M potassium dihydrogen phosphate in 30 % methanol, and 1 M ammonia in 30 % methanol. Detection by spraying with 2 % methanolic iron(III) chloride solution or with a solution of titanium tetrachloride in concentrated hydrochloric acid (20 %) followed by heating at 120 °C for 30 s or 2 min.

extracts on polar-bonded stationary phases. J. of Chromatogr. A 1218 (19), 2812-2819 (2011). Two-dimensional TLC of phenolic compounds (extracted from Polygonum hydropiper L. and Polygonum cuspidatum L.) on cyano phase with non-aqueous solvents in the first direction and aqueous solvents in the second direction. For the separation of standards the optimal chromatographic systems was determined based on the retention data collected in one-dimensional TLC experiments by plotting graphs of Rf vs. Rf dependencies.

J. AOAC Int. 97, 1274-1281 (2014). TLC fingerprint for the optimization of accelerated solvent extraction conditions for the isolation of total polyphenolic compounds from common thyme (Thymus vulgaris), on silica gel with ethyl acetate – formic acid – acetic acid – water 100:11:11:13. Detection by spraying with 10 % methanol solution of sulfuric acid, followed by heating at 110 °C for 20 min. Quantitative determination by absorbance measurement between 320 and 700 nm.

Planta Medica 82(3), 238-243 (2016). Pure 6-gingerol was submitted to sulfation either with purified human sulfatases (SULT1A1, SULT1A2, SULT1A3, SULT1B1, SULT1C2, SULT1C3, SULT1C4, SULT1E1, SULT2A1, SULT2B1a, SULT2B1b, SULT4A1, and SULT6B1) or with cytosol of human organs (lung, liver, small intestine, kidney), in presence of [35S]-marked 3’-phosphoadenosine 5’-phosphosulfate, and, after centrifugation (13000 rpm, 3 min), the supernatant was analyzed by TLC on silica gel with acetic acid – n-butanol 2:1. The plate was dried with a hair-drier. Detection by autoradiography on an X‑ray film; the radioactive band corresponding to the [35S]-sulfated 6-gingerol (hRf 76) was cut out and eluted with 0.5 mL water into a glass vial for liquid scintillation counting. The strongest 6-gingerol-sulfating activity was exhibited, among the enzymes tested, by SULT1A1 (followed by SULT1C4, SULT1A3, SULT1E1, SULT1A2 and SULT1B1, the other sulfatases being inactive), and, among the organ cytosols, by the small intestine (followed by liver, lung and kidney). The same procedure was applied to detect, after spin filtration, the same [35S]-sulfated 6-gingerol produced from 6-glycerol and [35S]-sulfate in presence of plate-cultured human cells HepG2 (hepatoma) and Caco-2 (colon adenocarcinoma); the amount of the produced sulfated form clearly depended on the gingerol concentration.

J. Liq. Chromatogr. Relat. Technol. 39, 698-701 (2016). HPTLC of resveratrol and saponins in syrup, powdered trunk, and bark samples of Yucca schidigera on silica gel with chloroform - methanol - water 35:14:1. Detection by spraying with 10 % sulfuric acid - ethanol solution followed by heating at 100 ºC. Qualitative identification at 254 nm. The hRF values for phenols were >38, where these were <38 for saponins.

(Peel). J. Planar Chromatogr. 30, 510-515 (2017). HPTLC of protocatechuic acid (1) and quercetin 4ʹ-O-β-D-glucopyranoside (2) in Allium cepa on silica gel with toluene – ethyl acetate – formic acid 3:6:1. Quantitative determination by absorbance measurement at 275 nm. The hRF values for (1) and (2) were 56 and 5, respectively. Linearity was between 100 and 700 ng/zone for (1) and (2). LOD and LOQ were 32 and 92 ng/zone for (1) and 30 and 92 ng/zone for (2). The intermediate precision was <2 % (n=6). Recovery ranged from 98.1 to 99.6 % for (1) and 98.2 to 99.9 % for (2).

J. Planar Chromatogr. 31, 230-234 (2018). HPTLC of hypoxoside in the roots of Hypoxis hemerocallidea on silica gel with chloroform – methanol – water 35:15:1. Quantitative determination by absorbance measurement at 257 nm. The hRf value for hypoxoside was 30. Linearity was in the range of 0.02-1.80 µg/mL. The LOD and LOQ for hypoxoside were 0.51 µg and 1.65 µg/mL. (Note by the editor: It can not be true that the start of calibration is below the LOD by a factor of 25.) The intermediate precision was below 5 %. Average recovery was 84 %.