J. Planar Chromatogr. 34, 549-557 (2021). HPTLC of brexpiprazole (1) and sertraline HCl (2) on silica gel with n-propanol - hexane - toluene - triethylamine 70:20:10:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) and (2) were 36 and 47, respectively. Linearity was between 4500 and 15000 ng/zone for (1) and 90 and 300 ng/zone for (2). Interday and intra-day precisions were below 4 % (n=3). The LOD and LOQ were 163 and 495 ng/zone for (1) and 35 and 107 ng/zone for (2), respectively. Recovery was between 99.5 and 101.1 % for (1) and 99.4 and 102.0 % for (2).

J. Planar Chromatogr. 34, 561-567 (2021). HPTLC of Ecuadorian Chenopodium quinoa Willd. leaf extracts on silica gel with formic acid - water - methyl ethyl ketone - ethyl acetate 1:2:4:3. Detection by heating at 105 °C for 60 min, followed by a three step derivatization method: 1) spraying with a 3 mL solution of α-amylase (5 U/mL of α-amylase in ethanol 10 %), followed by incubation at 37 °C for 30 min, 2) a 2 mL solution of starch (1 % of starch in ethanol 10 %) was applied on the plate, followed by incubation at 37 °C for 10 min, and (3) detection using iodine vapors for 2 min (1 g of solid iodine). The method allowed rapid localizing of α-amylase inhibitory compounds in complex plant matrices.

J. Planar Chromatogr. 34, 513-520 (2021). HPTLC of curcumin (1), piperine (2) and ascorbic acid (3) in a combined marketed formulation on silica gel with chloroform - methanol - ether - glacial acetic acid 95:3:1:1. Quantitative determination by absorbance measurement at 254 nm for (3) and in fluorescence mode at 366 nm for (1) and (2). The hRF values for (1) to (3) were 65, 83 and 28, respectively. Linearity was between 620 and 3040 ng/zone for (1), 470 and 2380 ng/zone for (2) and 530 and 2670 ng/zone for (3). Interday and intra-day precisions were below 2 % (n=3). 

J. Planar Chromatogr. 34, 521-530 (2021). HPTLC of piperine in Piper nigrum on silica gel with toluene - ethyl acetate 3:2. Quantitative determination by absorbance measurement at 254 nm. The hRF value for piperine was 63. Linearity was between 200 and 1000 ng/zone. Interday and intra-day precisions were below 1 % (n=3). The LOD and LOQ were 611 and 1778 ng/zone, respectively. Average recovery was 98.3 %.

J. Planar Chromatogr. 34, 543-548 (2021). HPTLC of mangiferin (1) and berberine (2) on silica gel with toluene - acetone - formic acid 7:11:2. Quantitative determination by absorbance measurement at 261 nm. The hRF values for (1) and (2) were 39 and 80, respectively. Linearity was between 400 and 800 ng/zone for (1) and 100 and 500 ng/zone for (2). Interday and intra-day precisions were below 2 % (n=5). The LOD and LOQ were 26 and 79 ng/zone for (1) and 19 and 18 and 56 ng/zone for (2), respectively. Average recovery was 101.2 % for (1) and 101.0 % for (2). The effect of various forced degradation conditions was observed.

J. Planar Chromatogr. 34, 559-560 (2021). HPTLC fingerprint of Ginkgo biloba finished products on silica gel with n-butyl acetate - methanol - water - formic acid 15:4:2:2. Detection by dipping into anisaldehyde reagent (1 mL of p-anisaldehyde in 200 mL of a mixture of methanol, acetic acid and sulphuric acid 17:2:1). Qualitative identification under UV light at 254 nm and 366 nm. 

J. Planar Chromatogr. 34, 531-542 (2021). HPTLC of betulinic acid (1), β‑sitosterol (2) and lupeol (3) in fruits, leaves, root and stem bark of Dillenia pentagyna on silica gel with petroleum ether - ethyl acetate - acetonitrile 82:18:1. Detection by dipping into anisaldehyde sulfuric acid reagent, followed by heating at 105 °C for 5 min. Quantitative determination by absorbance measurement at 580 nm. The hRF values for (1) to (3) were 17, 23 and 36. Linearity was between 120 and 440 ng/zone for (1), 200 and 1000 ng/zone for (2) and 60 and 220 ng/zone for (3). Interday and intra-day precisions were below 2 % (n=5). The LOD and LOQ were 91 and 276 ng/zone for (1), 304 and 921 ng/zone for (2) and 41 and 125 ng/zone for (3), respectively. Average recovery was 100.7 % for (1), 101.7 % for (2) and 102.0 % for (3). 

J. Planar Chromatogr. 34, 493-502 (2021). HPTLC of quercetin (1), beta-sitosterol (2), piperine (3), gallic acid (4) and resveratrol (5) in Krishnadi Churna on silica gel with toluene - chloroform - methanol 4:4:1 for (3), toluene - ethyl acetate - ethanol - methanol - formic acid 20:15:10:5:1 for (4), toluene - ethyl acetate - methanol - formic acid 50:40:10:2 for (1) and toluene - ethyl acetate - methanol - formic acid 60:30:10:3 for (2) and (5). Quantitative determination by absorbance measurement at 366 nm. The hRF values for (1) to (5) were 52 for (1), 64 for (2), 77 for (3), 61 for (4) and 45 for (5). Linearity was between 2 and 14 µg/mL for (1), (2) and (5), 1 and 18 µg/mL for (3) and 3 and 15 µg/mL for (4). The LOD and LOQ were 3 and 8 µg/zone for (1), 2 and 6 µg/zone for (2), 5 and 16 ng/zone for (3), 8 and 3 µg/zone for (4) and 8 and 3 µg/zone for (5). Average recovery was 99.2 % for (1), 98.4 % for (2), 98.6 % for (3), 98.9 % for (4) and 99.1 % for (5).