J. Liq. Chromatogr. Relat. Technol. 42, 324-329 (2019). HPTLC of individual pharmaceutical products containing moxifloxacin HCl (1), ofloxacin (2), amoxicillin trihydrate (3), acetylsalicylic acid + acetaminophen + caffeine (4), nimesulide (5), irbesartan (6), and pantoprazole (7) on silica gel with methanol - ammonium hydroxide - water 7:2:1 for (1), methanol - ethyl acetate - ammonium hydroxide 7:7:3 for (2), acetone - water - methanol - glacial acetic acid 20:10:5:2 for (3), ethyl acetate - glacial acetic acid 19:1 for (4), toluene - acetone 10:1 for (5), ethyl acetate - acetone - glacial acetic acid 180:40:1 for (6) and ethyl acetate - methanol - toluene 4:1:2 for (7). Quantitative determination by absorbance measurement at 366 nm. The hRF values for (1) to (3) and (5) to (7) were 72, 30, 80, 33, 40 and 43, respectively. The hRF values for (4) were 62 for acetylsalicylic acid, 49 for acetaminophen and 22 for caffeine. The quantitative methods were used to transfer the Global Pharma Health Fund (GPHF) Minilab Manual and U.S. Food and Drug Administration (FDA) Compendium to HPTLC following a model process for moxfloxacin HCl, ofloxacin, and amoxicillin trihydrate. The results met the guidelines of the model process regarding the calibration curves: r-values were at least 0.99, assays were within 85–115% specification limits of the label values of individual tablets and capsules, validation recoveries were within 95 - 105 % at all three spike levels, RSDs were no higher than 3 % for assays and validation analyses, and peak identity and peak purity checks had correlation factors of at least
0.99. 
 

J. Chinese Trad. Patent Med. 40 (11), 2450-2454 (2018). Dabaidu Jiaonang capsules are used for clearing blood poison and relieving swelling and pain. For quality control, TLC of its extracts, the respective reference drug and selected standards on silica gel (1) for Rheum palmatum L., with petroleum ether (30-60 ˚C) – ethyl formate – formic acid 15:5:1, detection under UV 365 nm; (2) for Cortex phellodendri (and berberine hydrochloride), with n-butanol – glacial acidic acid – water 7:1:2, detection under UV 365 nm; (3) for Radix paeoniae rubra (and paeoniflorin), with chloroform – ethyl acetate – methanol – formic acid 40:5:10:0.2, detection by spraying with 5% vanilline in H2SO4 – ethanol 1:4 and heating at 85 ˚C until the zones are visible in daylight; (4) for Angelica dahurica (Fisch. ex Hoffm.) Benth. et Hook. f. ex Franch. et Sav (and iso-/imperatorin), with petroleum ether (30-60 ˚C) – diethyl ether 3:2, detection under UV 365 nm; (5) for Pericarpium citri reticulatae (and hesperidin), first with ethyl acetate – methanol – water 100:17:13 up to 30 mm, then with the upper phase of toluene – ethyl acetate – formic acid – water 20:10:1:1 up to 80 mm, detection by spraying with 5% AlCl3 in ethanol and viewing under UV 365 nm; (6) for Boswellia carteri, with cyclohexane – ethyl acetate 11:2, detection by spraying with 5% vanilline in H2SO4 – ethanol 1:4 and heating at 85 ˚C until the zones are visible in daylight. Quantification of aloe emodin, rhein, emodin, chrysophanol, physcion by HPLC.

J. Liq. Chromatogr. Relat. Technol. 42, 238-248 (2019). Review of recent applications of TLC in medicinal chemistry, including the determination of lipophilicity of biologically active compounds and its influence as activity descriptors of absorption, distribution, metabolism, elimination and toxicity. Practical applications of TLC as a fast screening technique in different stages of monitoring processes were also described, including systems recently used for stability studies of selected drugs.

Planta Med. 83(17), 1321-1328 (2017). Benzoyl-aconine esters (lipo-alkaloids) produced by transesterification of aconitine (isolated from Aconitum sp.) with long-chain fatty acids were purified by a multistep chromatographic method, including cyclodextrane gel filtration chromatography, centrifugal planar chromatography on aluminium oxide layer using cyclohexane – chloroform – methanol 70:30:1 followed by 70:30:3 and/or preparative thin-layer chromatography on aluminium oxide layer with toluene – acetone – ethanol – concentrated ammonia 70:40:10:3.

Planta Med. 83(16), 1289-1296 (2017). A cycloartene-diol, a dihydroxycicloartenone and an isopimaradiene-diol were isolated from subfractions of an ethanolic extract of Guarea macrophylla (Meliaceae) leaves through elution on preparative TLC silica gel layers with chloroform – acetone 19:1, or with n-hexane – ethyl acetate 9:1 or 1:1, respectively.

Planta Med. 83(14/15), 1233-1241 (2017). HPTLC of standards and methanolic extracts of L. cardiaca, L. japonicus and L. sibiricus (Lamiaceae) acidified with formic acid on silica gel with ethyl acetate – acetic acid – formic acid – water 100:11:11:26, in an automatic development chamber with 48 % humidity (20 min presaturation). Detection under white and UV light, before and after immersion in 1) anisaldehyde – sulphuric acid (followed by heating) for the detection of iridoids; 2) natural product reagent A for phenylpropanoids; 3) modified Dragendorff reagent (bismuth oxynitrate 0.17 %, sulfuric acid 3.5 %, glacial acetic acid 2 %, potassium iodide 4 %) for alkaloids. Ajugoside (hR_F 29) and verbascoside (hR_F 53) were found in L. cardiaca and L. sibiricus, but absent in L. japonicus. The opposite was true for leonurine (hR_F 52), whereas stachydrine (hR_F 14) was found in the three species. This method allows to distinguish L. japonicus from the other species, which have to be distinguished from each other through morphology.

J. Planar Chromatogr. 32, 273-283 (2019). HPTLC of trimetazidine dihydrochloride (1) and its potential impurities, namely, piperazinecarboxaldehyde (2), trimethoxybenzyl alcohol (3), and trimethoxybenzaldehyde (4) on RP-18 with acetonitrile - methanol - 0.1 % aqueous ortho-phosphoric acid (pH 6.2) 9:9:2. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (4) were 21, 35, 50 and 85, respectively. Linearity was between 0.05-10 µg/zone for (1), 0.05-1.1 µg/zone for (2), 0.05-1.2 µg/zone for (3) and 0.04-1.0 µg/zone for (4). The intermediate precision was below 2 % (n=9). The LOD and LOQ were 20 and 50 ng/zone for (1) to (3) and 15 and 40 ng/zone for (4), respectively. Recovery rate was 99.6 % for (1), 100.5 % for (2), 100.1 % for (3) and 99.4 % for (4).

J. Planar Chromatogr. 32, 317-321 (2019). HPTLC of 2-chloroaniline (1) at trace levels
in quetiapine fumarate (2) on silica gel with toluene and methanol 7:4. Quantitative determination by absorbance measurement at 235 nm. The hRF value of (1) was 85. Linearity was between 2.5-12.5 ng/zone for (1) and 400-2400 ng/zone for (2). The intermediate precision was below 2 % (n=3). The LOD and LOQ of (1) were 0.02 and 0.05 ng/zone for (1) [Editor´s note: This seems to be erroneous.] and 1.27 and 3.87 ng/zone for (2), respectively. Recovery rate ranged between 98 and 100 % for (1) and (2).