J. Planar Chromatogr. 33, 191-201 (2020). HPTLC of rutin in the leaves of Phoenix sylvestris on silica gel with chloroform - methanol - formic acid 10:40:1. Quantitative determination by absorbance measurement at 265 nm. The hR_F value for rutin was 71. Linearity was between 200 and 1000 ng/zone. Intermediate precisions were below 2 % (n=5). The LOD and LOQ were 125 and 205 ng/zone. Average recovery was found to be in the range of 99.0-100.0 %.

J. Planar Chromatogr. 33, 79-87 (2020). HPTLC of quercetin in the aerial parts of Juniperus communis, J. horizontalis and J. chinensis on silica gel with ethyl acetate - methanol - water - acetic acid 900:80:40:7. Assessment of peroxidase inhibition activity by dipping into peroxidase enzyme solution (10 mg/mL solution of peroxidase in cold phosphate buffer (pH 7), followed by dilution with 50 mL of phosphate buffer, pH 7) for 3 s, followed by heating at 35 ºC for 2 min, dipping into a hydrogen peroxide solution and finally dipping into a benzidine solution (4 g in 700 mL methanol). Linearity was between 0.85 and 9 µg/zone for quercetin. Intermediate precisions were below 3 % (n=3). The LOD and LOQ were 280 and 850 ng/zone. Recovery was between 96.6 and 99.7 %.

J. Planar Chromatogr. 33, 27-32 (2020). HPTLC of rutin (1), chlorogenic acid (2) and gallic acid (3) in the seeds of Moringa oleifera on silica gel with ethyl acetate - acetone - water - formic acid 6:3:2:2. Quantitative determination by absorbance measurement at 254 nm. The hR_F values for (1) to (3) were 51, 72 and 83, respectively. Linearity was between 1000 and 7000 ng/zone for (1), 100 and 700 ng/zone for both (2) and (3). Intermediate precisions were below 1 % (n=6). The LOD and LOQ were 5 and 17 ng/mL for (1), 7 and 22 ng/mL for (2) and 7 and 20 ng/mL for (3), respectively. Recovery rate was between 98.1 and 99.5 % for (1), 98.8 and 99.5 % for (2) and 97.6 and 98.6 % for (3).

J. Planar Chromatogr. 33, 33-41 (2020). HPTLC fingerprint of the kernel and seed of Allanblackia parviflora fruit (extracted with methanol - water 4:1) on silica gel with methanol - water - ethyl acetate 33:27:200. Detection by spraying with vanillic acid - sulfuric acid reagent (1 g of vanillic acid in 100 mL of 96 % ethanol, followed by the dropwise addition of 2 mL concentrated sulfuric acid). Different formulations of the derivatization reagent were investigated and the use of vanillic acid instead of the more frequently used vanillin provided a better result. Qualitative determination under UV 254 and 366 nm. Consistent hR_F values of the main zones under UV 254 nm were 39, 35 and 12. For the derivatized plate, consistent hR_F values of the main zones were 39, 34, 31 and 22.

Planta Medica 84(2), 129-134 (2018). TLC of subfractions obtained from normal-phase LC and size-exclusion chromatography of an ethanolic extract of Bougainvillea spectabilis (Nyctaginaceae) stem-bark on RP-18 with methanol – water 2:3 and 1:1 to isolate six flavones (bougainvinones J, K, L, M, and two dimethylflavone derivatives).

Planta Medica 84(1), 59-64 (2018). A multi-step fractionation through silica gel column chromatography (CC) of a methanolic extract of Plectranthus africanus (whole plant, Lamiaceae) was monitored through TLC on silica gel with various solvent mixtures (n-hexane or dichloromethane with either acetone or methanol). Zones were detected under UV and further by spraying with sulfuric acid 20 % and heating at 100°C. For each fraction or TLC profile, the authors provide the CC gradient, the optimal proportions of the solvents used for the TLC mobile phase, as well as the RF values of the molecules isolated by this CC method: new abietane-type diterpenoids (plectranthroyleanones A, B, C), betulinic and oleanolic acids, heterosides of apigenin, rhamnetin and sitosterol.

J. Liq. Chromatogr. Relat. Technol. 42, 563-569 (2019). HPTLC of spinosin in the fruits of Ziziphus jujuba on silica gel with ethyl acetate - dichloromethane - methanol - water 18:10:15:5. Quantitative determination by absorbance measurement at 334 nm. The hRF value for spinosin was 38. Linearity was between 10 and 120 ng/mL. Intermediate precision was below 2 % (n=6). The LOD and LOQ were 12 and 35 ng/mL, respectively. Recovery rate was between 98.7 and 101.3 %. The HPTLC method provided similar reproducibility, accuracy and selectivity for the quantitative determination of spinosin compared with a HPLC method.

J. AOAC Int. 102, 1003-1013 (2019). HPTLC of quercetin (1) and berberine (2) in Pushyanuga Churna on silica gel with toluene - ethyl acetate - methanol - formic acid 6:6:2:1. Quantitative determination by absorbance measurement at 254 nm for (1) and 366 nm for (2). The hRF values for (1) and (2) were 63 and 24, respectively. Intermediate precisions were below 2 % (n=3). The LOD and LOQ were 1 and 3 µg/mL for (1) and 0.05 and 0.1 µg/mL for (2), respectively. Recovery rate was between 93.5 and 100.6 % for (1) and 95.2 and 97.6 % for (2).