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.

J. Planar Chromatogr. 33, 89-95 (2020). Thin-layer electrophoresis of inorganic anions F-, Cl-, Br-, I-, IO3-, IO4-, BrO3-, IO3-, Fe(CN)63- and Fe(CN)64- on (1) silica gel, (2) titanium (IV) tungstate and (3) admixture of silica gel and titanium (IV) tungstate 1:1 for 2 h at 100 V using 0.1 M oxalic acid, 0.1 M citric acid, 0.1 M tartaric acid, 0.1 M succinic acid and 0.1 M acetic acid as background electrolyte. Silica gel was effective in achieving binary, ternary and quaternary separations. The magnitude of migration was in accord with the order of lyotropic number.

Planta Medica 84(6/7), 465-474 (2018). The new concept “Comprehensive HPTLC Fingerprinting” was applied to define specifications for the identification and purity assessment of Angelica gigas roots, and for the quantification of its markers: the coumarins decursin and decursinol angelate. Methanolic root extracts of A. gigas (10 reference materials, 24 commercial samples), of 26 other Apiaceae species (including 10 Angelica, 9 Ligusticum, 2 Notopterygium, 4 Peucedanum, and Levisticum officinale) and of mixtures, were developed with toluene - ethyl acetate - acetic acid 90:10:1 on HPTLC silica gel (at 33% relative humidity, chamber pre-saturated for 20 min with filter paper and developing solvent) and dried for 5 min. Detection under white and UV lights before and after derivatization by dipping into 10% sulfuric acid in methanol and then heating 3 min at 100°C. Quantitative evaluation by densitometry in fluorescence mode at UV 313 nm, and luminance was also calculated from the image pixels. The study showed the presence in A. gigas of nodakenin, decursinol, 7-demethylsuberosin, imperatorin, osthole, and isoimperatorin at hRF 0, 4, 15, 33, 38 and 44 respectively. Z-ligustilide (hRF 59) was absent from A. gigas, allowing 1) to distinguish it from several other Apiaceae species; 2) to identify in mixtures with A. gigas two common adulterants (A. acutiloba, A. sinensis) even at 1% in the root powder. Minimal content of A. gigas fingerprint markers (decursin + decursinol acetate, co-eluting at hRF 27) was assessed as 3% (w/w) based on the quantified peaks from A. gigas reference materials.

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. Liq. Chromatogr. Relat. Technol. 42, 563-569 (2019). TLC of 17 new anti-proliferative and antiinflammatory tetracyclic 6-substituted 9-fluoroquinobenzothiazines on RP-18 with acetone - aqueous TRIS (tris(hydroxymethyl)-aminomethane) buffer pH 7.4 (ionic strength 0.2 M), where the concentration of acetone was from 50 to 85 % in 5 % increments. Lipophilicity parameters were determined (R_M0 and logP_TLC) and compared with computationally calculated lipophilic parameters. Relation of lipophilicity with predicted and experimental biological activities was discussed.
 

J. of Modern Trad. Chinese Med. 20 (8), 975-978 (2018). Panax notoginseng is a traditional Chinese medicinal herb which activates blood circulation, anti-platelet aggregation and anti-thrombosis. TLC for quality control of ginsenoside Rb1 (1), notoginsenoside R1 (2) and ginsenoside Rg1 (3) on silica gel with the lower phase of chloroform – methanol – water 13:7:2 (after standing for 12 h at below 10˚C). Detection by spraying with 10% sulfuric acid in ethanol and heating at 110 ˚C until the zones are visible, evaluation under UV 365 nm. Quantification by densitometric absorption measurement at 510 nm. Validation by investigation of the linearity ranges of 0.5-5.0 µg/zone (r=0.998) for (1), 0.5-5.01 µg/zone (r=0.999) for (2) and 0.5-4.9 µg/zone (r=0.998) for (3). The plate-to-plate precision % RSD (n=12) was 1.5 %, 1.1 % and 1.9 % for (1) to (3). Recovery from standard sample addition was 96.4 % (%RSD 1.4 %, n=6) for (1), 96.9 % (%RSD 0.9 %, n=6) for (2), and 98.9% (%RSD 1.7 %, n=6) for (3).

J. of Chromatogr. A 1534, 170-178 (2018). HPTLC of flavonoid aglycones in eleven commercial Cistus incanus herbal teas using three independent methods (multi-development on amino phase and two two-dimensional developments on silica gel phase). HPTLC on silica gel with chloroform - methanol - ethyl acetate 15:3:2. Detection at UV 254 and 366 nm and by derivatization with aluminium chloride (1 % methanolic solution), ferric chloride (0.5 g FeCl₃ in 2.5 mL water and 47.5 mL ethanol), NP-PEG (0.5 % methanolic NP solution, and after drying, 5 % ethanolic PEG solution), PABA (0.5 g PABA in 18 mL glacial acetic acid diluted with 20 mL water, plus 1 mL o-phosphoric acid and 60 mL acetone), or DPA reagents (1 g aniline and 1 g diphenylamine in 100 mL acetone and 10 mL o-phosphoric acid, heated for 5 min at 110°C). Confirmation of the presence of glucose by HPTLC on amino phase with in situ acid hydrolysis: incubation in HCl vapor followed by heating at 100°C, pre-development with acetonitrile, drying, development with acetonitrile - water 7:3, heating for 20 min at 170°C and dipping in paraffin - n-hexane 1:2 follwed by drying. TLC-direct bioautography by immersion of the developed and dried plates in a bacterial cell suspension of either Bacillus subtilis or Aliivirio fischeri strains. Analysis of the compounds isolated from the bioactive zones by HPLC-diode array detector (DAD)-electrospray ionization (ESI)-MS. The presented TLC/HPTLC platform allowed identification of the antibacterial components apigenin, kaempferide, cis- and trans-tiliroside, and the isomers of the p-coumaric acid-conjugated tiliroside,  all of them inhibiting both B. subtilis and A. fischeri.

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.