J. Planar Chromatogr. 35, 89-95 (2022). HPTLC of epimers (+)‑catechin (1) and (-)‑epicatechin (2) in Onosma bracteatum on silica gel with diisopropyl ether - ethyl acetate - formic acid 90:2:7. Detection by spraying with p-toluenesulfonic acid reagent, followed by heating at 110 °C. Quantitative determination by absorbance measurement at 280 nm. The hRF values for (1) and (2) were 47 and 37, respectively. Linearity was between 1000 and 5000 ng/zone for (1) and (2). Interday and intra-day precisions were below 2 % (n=3). The LOD and LOQ were 284 and 863 ng/zone for (1) and 183 and 611 ng/zone for (2). Average recovery was 98.9 % for (1) and 99.0 % for (2).

J. Planar Chromatogr. 35, 73-81 (2022). HPTLC of omeprazole (1) and its impurity 4‑methoxy‑2‑nitroaniline (1) on silica gel with methanol - n-hexane - ethyl acetate 1:10:11. Quantitative determination by absorbance measurement at 291 and 223 nm for (1) and (2), respectively. The hRF values for (1) and (2) were 25 and 89, respectively. Linearity was between 100 and 500 ng/zone for (1) and 10 and 50 ng/zone for (2). Interday and intra-day precisions were below 1 % (n=3). The LOD and LOQ were 3.2 and 9.8 ng/zone for (1) and 0.41 and 1.25 ng/zone for (2), respectively. Recovery was in the range of 98-102 % for (2).

J. Planar Chromatogr. 35, 61-71 (2022). HPTLC of empagliflozin (1) in the presence of metformin HCl (2) on silica gel with toluene - methanol - ammonia - glacial acetic acid 72:26:1:1. Quantitative determination by absorbance measurement at 230 nm. The hRF values for (1) and (2) were 15 and 48, respectively. Linearity was between 11 and 112 ng/zone for (1) and 85 and 850 ng/zone for (2). Interday and intra-day precisions were below 2 % (n=3). The LOD and LOQ were 0.6 and 1,7 ng/zone for (1) and 5 and 15 ng/zone for (2), respectively. Recovery was found to be in the range of 99.4-101.0 % for (1) and 100.3-101.4 % for (2). Degradation products were characterized by liquid chromatography coupled with electrospray ionization‒quadrupole-time of flight‒tandem mass spectrometry (LC‒ESI‒QTOF‒MS/MS).

J. Planar Chromatogr. 35, 23-33 (2022). HPTLC of 6‑gingerol (1), guggulsterone (2) E and guggulsterone Z (3) on silica gel with toluene - acetone 9:1. Quantitative determination by absorbance measurement at 280 nm. The hRF values for (1) and (2) were 15, 19 and 25, respectively. Linearity was between 100 and 1200 ng/zone for (1) to (3). Interday and intra-day precisions were below 3 % (n=5). The LOD and LOQ were 100 and 400 ng/zone for (1) to (3), respectively. Recovery was between 95.4 and 101.05 %. 

J. Planar Chromatogr. 35, 83-88 (2022). HPTLC of enantiomers of (RS)-fluoxetine on silica gel impregnated with a nanocomposite of β-cyclodextrin and 3D graphene (G/β-CD NC) with methanol - acetonitrile - water 4:3:1. Detection by exposure to iodine vapor. Average precision was below 2 %. LOD and LOQ were 1.8 and 5.4 mg/mL, respectively. Recovery was between 86 and 94 %.

J. Planar Chromatogr. 35, 51-59 (2022). HPTLC of codeine (1), paracetamol (2), p-aminophenol (3) and caffeine (4) on silica gel with chloroform - methanol - acetone - ammonia 80:10:20:1. Quantitative determination by absorbance measurement at 220 nm. The hRF values for (1) to (4) were 24, 38, 46 and 61, respectively. Linearity was between 0.3 and 120 µg/zone for (1) and (4) and 1 and 20 µg/zone for (2) and (3). Interday and intra-day precisions were below 1 % (n=3). The LOD and LOQ were 0.06 and 0.21 µg/zone for (1), 0.23 and 0.7 µg/zone for (2), 0.24 and 0.82 µg/zone for (3) and 0.07 and 0.82 µg/zone for (4), respectively. Average recovery was 101.4 % for (1), 100.1 % for (2), 98.9 % for (3) and 98.3 % for (4).

J. Planar Chromatogr. 35, 35-41 (2022). HPTLC of quercetin (1) and gallic acid (2) in the leaves of Annona reticulata on silica gel with toluene - ethyl acetate - formic acid 45:50:8. Quantitative determination by absorbance measurement at 367 nm. The hRF values for (1) and (2) were 71 and 63, respectively. Linearity was between 200 and 1000 ng/zone for (1) and 200 and 1200 ng/zone for (2). Interday and intra-day precisions were below 2 % (n=5). The LOD and LOQ were 21 and 65 ng/zone for (1) and 15 and 55 ng/zone for (2), respectively. Recovery was between 98.0 and 99.1 % for (1) and 99.3 and 100.3 % for (2).

J. Planar Chromatogr. 35, 3-12 (2022). HPTLC of alisol B 23-acetate (1), alisol B (2), alisol A (3) and alisol C 23-acetate (4) in the rhizomes of Alisma orientale on silica gel with cyclohexane - ethyl acetate 1:1. The hRF values for (1), (4), (2) and (3) were 62, 42, 28 and 9, respectively Quantitative determination by absorbance measurement at 254 nm for (1) and 208 nm for (2), (3) and (4). Linearity was between 125 and 2000 μg/zone for (1) and 83 and 2000 μg/zone for (2), (3) and (4). Interday and intra-day precisions were below 1 % (n=3). Average recovery was 94.2 % for (1), 90.3 % for (2), 97.0 % for (3) and 90.2 % for (4).