J. Liq. Chromatogr. Relat. Technol. 43, 580-588 (2020). Retardation factor (hRF) of 42 amino acids in two different eluents (acetonitrile - sodium azide and 1,2 dioxane-sodium azide solutions) were predicted by different quantitative structure-retention relationship (QSRR) methods. The method analyzed the effect of sum of geometrical distances between N and O in separation of amino acids in RP-TLC.

J. Planar Chromatogr. 33, 281-291 (2020). HPTLC of Weikangling capsules (a Chinese patent medicine for treating chronic gastritis, containing Paeoniae Radix Alba, Glycyrrhizae Radix et Rhizoma, Bletillae Rhizoma, Notoginseng Radix et Rhizoma, Poria, Corydalis Rhizoma, Sepiae Endoconcha, and Belladonnae Extractum) on silica gel with chloroform - methanol - water 14:5:1. Detection by spraying with 10 % sulfuric acid in alcohol, followed by heating at 105 ºC for 5 min. Qualitative analysis at UV 366 nm.

J. Planar Chromatogr. 33, 523-530 (2020). HPTLC of clonazepam (1), lorazepam (2), alprazolam (3), diazepam (4), furazepam (5), oxazepam (6) and nitrazepam (7) in urine on silica gel with chloroform - glacial acetic acid 9:1. Direct extraction of the substances from the plate into a mass spectrometer. The hRF values for (1) to (7) were 73, 44, 22, 64, 18, 53 and 40, respectively. Linearity was between 0.2 and 0.8 µg/mL. Intermediate precision was below 5 %. LOD was 1 ng/mL for each substance. Average recovery was 67.1 % for (1), 68.9 % for (2), 64.2 % for (3), 73.1 % for (4), 50.7 % for (5), 81.4 % for (6) and 64.4 % for (7).

J. Planar Chromatogr. 33, 481-487 (2020). HPTLC of resveratrol in the fruits of Morus alba on silica gel with hexane - ethyl acetate - glacial acetic acid 40:60:1. Quantitative determination by absorbance measurement at 302 nm. The hRF value for resveratrol was 56. Linearity was between 100 and 1600 ng/zone. Intermediate precision was below 2 % (n=6). The LOD and LOQ were 16 and 46 ng/zone, respectively. Recovery was between 90.3 and 96.5 %.

J. Planar Chromatogr. 33, 457-462 (2020). HPTLC of scopoletin (1) and gallic acid (2) in the aerial parts of Jatropha glandulifera on silica gel with toluene - ethyl acetate - glacial acetic acid 75:25:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) and (2) were 69 and 40, respectively. Linearity was between 100 and 600 ng for (1) and (2). Intermediate precision was below 2 % (n=3). The LOD and LOQ were 70 and 200 ng for (1) and 40 and 100 ng for (2), respectively. Recovery was between 98.8 and 98.9 % for (1) and 97.4 and 98.1 % for (2).

J. Planar Chromatogr. 33, 473-479 (2020). HPTLC of rutin (1), gallic acid (2) and quercetin (3) in the aerial parts of Euphorbia hirta and Euphorbia thymifolia on silica gel with toluene - ethyl acetate - methanol - formic acid 30:15:13:4. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (3) were 2, 56 and 72, respectively. Linearity was between 40 and 480 ng/zone for (1) to (3). Intermediate precision was below 2 % (n=3). The LOD and LOQ were 15 and 45 ng/zone for (1), 45 and 139 ng/zone for (2) and 20 and 61 ng/zone for (3), respectively. Recovery ranged 98.3-100.2 % for (1), 98.5-99.6 % for (2) and 95.5-99.1 % for (3).

J. Planar Chromatogr. 33, 463-472 (2020). HPTLC of chlorogenic acid in the fruit extracts of Lufa acutangula, Sechium edule, Trichosanthes cucumerina and Trichosanthes dioica on silica gel with ethyl acetate - chloroform - formic acid 12:8:1. Quantitative determination by absorbance measurement at 254 nm. The hRF value for chlorogenic acid was 55. Linearity was between 200 and 1000 ng/zone. Intermediate precision was below 2 % (n=3). Recovery was between 99.7 and 99.9 %.

J. Planar Chromatogr. 33, 501-509 (2020). HPTLC of chloramphenicol (1), dexamethasone sodium phosphate (2) and tetrahydrozoline HCl (3) in the absence or presence of p-nitroacetophenone (4) on silica gel with ethanol - water - ammonia 14:5:1 (method A) and acetonitrile - water - ammonia 20:6:1 (method B). Quantitative determination by absorbance measurement at 242 and 220 nm. The hRF values for (1) to (3) were 76, 65 and 20, respectively, in method A and the hRF values for (1) to (4) were 78, 38, 58 and 87, respectively, in method B. Linearity was 0.1-1.4 µg/zone for (1), 0.2-1.2 µg/zone for (2) and 0.1-0.5 µg/zone for (3) in method A and 0.6-1.8 µg/zone for (1), 0.8-3.2 µg/zone for (2), 0.01-0.1 µg/zone for (3) and 0.3-1.4 µg/zone for (4) in method B. Intermediate precision was below 2 % (n=3). The LOD and LOQ were 30 and 90 ng/zone for (1), 40 and 120 ng/zone for (2) and 20 and 60 ng/zone for (3) in method A and 60 and 180 ng/zone for (1), 130 and 390 ng/zone for (2), 3 and 9 ng/zone for (3) and 70 and 210 ng/zone for (4) in method B. Average recovery was 100.1 % for (1), 100.2 % for (2), 100.6 % for (3) in method A and 100.1 % for (1), 99.9 % for (2) and 100.2 % for (3) in method B.