Int. J. Morphol. 37, 1164-1171 (2019). HPTLC of transresveratrol in traditional fermented soybean seed coat on silica gel with chloroform - ethyl acetate - formic acid 25:10:1. Qualitative identification under UV light at 254 and 366 nm. The hRF value for transresveratrol was 64.

Rev. Bras. Farmacogn. 29, 177-181 (2019). HPTLC of chlorogenic acid (1), 3,4-O-dicaffeoylquinic acid (2), and 3,5-O-dicaffeoylquinic acid (3) in the leaves of Pluchea indica on silica gel with ethyl acetate - water - formic acid - toluene 20:2:2:1. Quantitative determination by absorbance measurement at 326 nm. The hRF values for (1) to (3) were 34, 63 and 79, respectively. Linearity was between 100 and 400 ng/zone for (1) to (3). Intermediate precisions were below 3 % (n=3). The LOD and LOQ were 9.9 and 30.1 ng/zone for (1), 17.6 and 53.3 ng/zone for (2) and 6.7 and 20.2 ng/zone for (3), respectively. Recovery rate was 99.0 % for (1), 97.5 % for (2) and 99.6 % for (3).

Food Chem. 288, 1-7 (2019). HPTLC of sesamin (1) and sesamolin (2) in sesame seed extracts on silica gel with n-pentane - diethyl ether 3:2. Quantitative determination by absorbance measurement at 290 nm. Linearity was between 25 and 150 µg/mL for (1) and 12.5 and 75 µg/mL for (2). Intermediate precision was below 3 % (n=6). The LOD and LOQ were 1.3 and 4 µg/mL for (1) and 0.4 and 1 µg/mL for (2), respectively. Recovery rate was  between 95 and 105 % for (1) and (2). Correlation of the HPTLC and a HPLC-PDA method was notably high. 

J. Planar Chromatogr. 32, 447-451 (2019). HPTLC of Fritillaria cirrhosa on silica gel with ethyl acetate - methanol - ammonia solution - water 180:20:10:1. Bioautography by dipping into a 0.15 mg/mL solution of substrate Gly-Pro-p-nitroanilide hydrochloride in 50 % of ethanol, followed by ethanol removal in the hood and dipping into a 10 U/L DPP IV enzyme solution in TrisHCl buffer (pH 8.2, 70 mM), followed by incubation at 37°C for 40 min. Detection by dipping into a solution of 0.5 % sodium nitrite in 1.2 M hydrochloric acid, followed by drying slightly for 5 min and dipping into 0.05 % N-(1-naphthyl)ethylenediamine dihydrochloride solution. Further analysis by mass spectrometry using a TLC interface. The hRF value for the dipeptidyl peptidase IV inhibitor was 58.

J. Planar Chromatogr. 32, 411-420 (2019). HPTLC of oleuropein in olive leave samples belonging to 9 different Egyptian olive varieties on RP-18 with methanol - acetonitrile 7:3. Detection by dipping into a methanolic 2-aminoethyldiphenylborane reagent (0.5 %), followed by drying and dipping into methanolic PEG 400 solution (5 %). Qualitative determination under UV light at 366 nm. Captured images were processed using the ImageJ software in order to build 2 separate data matrices (before and after derivatization). Quantitative determination by absorbance measurement at 240 nm. The hRF value for oleuropein was 35. Linearity was between 0.1 and 0.6 µg/zone.  Intermediate precision was below 1 % (n=6). The LOD and LOQ were 0.07 and 0.22 µg/zone. Recovery rate was 100.5 %.

J. Planar Chromatogr. 32, 467-474 (2019). HPTLC of quercetin in the fresh fruits of Benincasa hispida on silica gel with toluene - ethyl acetate - formic acid 25:20:1. Quantitative determination by absorbance measurement at 262 nm. The hRF value for quercetin was 39. Linearity was between 100 and 1200 ng/zone. Intermediate precision was below 2 % (n=6). The LOD and LOQ were 20 and 60 ng/zone. Recovery rate was 94.3 %.

J. Planar Chromatogr. 32, 461-465 (2019). HPTLC of betulinic acid (1), oleanolic acid (2) and lupeol (3) on silica gel with benzene - ethyl acetate - formic acid 679:227:94 for (1), n-hexane - ethyl acetate - glacial acetic acid 40:20:1 for (2) and n-hexane - ethyl acetate 4:1 for (3). Detection by spraying with anisaldehyde sulfuric acid, followed by heating at 105-110 ºC for 5-10 min. Quantitative determination by absorbance measurement at 530 nm. The hRF values for (1) to (3) were 79, 46 and 44, respectively. Intermediate precision was below 2 % (n=3).

J. Planar Chromatogr. 32, 379-384 (2019). HPTLC of trigonelline (1) and diosgenin (2) in the seeds of Trigonella foenum-graecum L. on silica gel with acetonitrile - water 3:1. Quantitative determination by absorbance measurement at 267 nm for (1) and at 430 nm after derivatization with vanillin - sulfuric acid for (2). The hRF values for (1) and (2) were 29 and 17, respectively. Linearity was between 200 and 1400 ng/zone for (1) and 50 and 300 ng/zone for (2). Intermediate precision was below 2 % (n=6). The LOD and LOQ were 7 and 1 ng/mL for (1) and 7 and 19 ng/mL for (2), respectively. Recovery rate was between 97.8 and 99.1 % for (1) and 98.2 and 99.3 % for (2), respectively.