J. Planar Chromatogr. 35, 463-471 (2022). HPTLC of naringin in the peels of Citrus sinensis on silica gel with glacial acetic acid - chloroform - water - methanol 10:30:1:5. Detection by heating at 60 °C for 5 min. Quantitative determination by absorbance measurement at 296 nm. The hRF value for naringin was 45. Linearity was between .04 and 2.0 µg/zone. Interday and intra-day precisions were below 1 % (n=3). The LOD and LOQ were 6 and 19 ng/zone. Average recovery was 99.4 %.

J. Planar Chromatogr. 35, 453-461 (2022). HPTLC of mangiferin (1), berberine (2), gallic acid (3), and quercetin (4) in Amritamehari churnam on silica gel with toluene - ethyl acetate - formic acid - methanol 5:4:1:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (4) were 13, 32, 49 and 64, respectively. Linearity was between 50 and 1000 ng/zone for (1), 100 and 1000 ng/zone for (2), 1200 and 2600 ng/zone for (3) and 100 and 800 ng/zone for (4). Interday and intra-day precisions were below 3 % (n=3). Average recovery was 93.7 % for (1), 91.2 % for (2), 94.5 % for (3) and 99.0 % for (4).

J. Planar Chromatogr. 35, 421-430 (2022). HPTLC of rutin (1), chlorogenic acid (2), hyperin (3), isoquercitrin (4) and astragalin (5) on silica gel with ethyl acetate - formic acid - water - toluene 18:2:2:1. Quantitative determination by absorbance measurement at 318 nm. Linearity was between 33 and 1139 ng/zone for (1), 13 and 1048 ng/zone for (2), 14 and 1110 ng/zone for (3), 1 and 298 ng/zone for (4) and 2 and 711 ng/zone for (5). The LOD and LOQ were 4 and 14 ng/zone for (1), 3 and 13 ng/zone for (2), 3 and 14 ng/zone for (3), 1 and 5 ng/zone for (4) and 2 and 9 ng/zone for (5), respectively. Average recovery was 100.0 % for (1), 98.6 % for (2), 96.6 % for (3), 94.7 % for (4) and 98.1 % for (5).

J. Planar Chromatogr. 35, 383-393 (2022). HPTLC of baicalin in the stem barks of Oroxylum indicum on silica gel with acetone - ethyl acetate - water - formic acid 4:20:1:1. Quantitative determination by absorbance measurement at 318 nm. The hRF value for baicalin was 49. Linearity was between 0.2 and 1.0 µg/zone. Interday and intra-day precisions were below 1 % (n=3). The LOD and LOQ were 56 and 188 ng/zone. Average recovery was 99.2 %.

J Chromatogr A, 1598, 209-215 (2019). Samples were methanolic extracts of honeys from Robinia pseudoacacia (Fabaceae) or from Tilia spp. (Tiliaceae / Malvaceae), as well as standards: abscisic acid (sesquiterpenoid), caffeic acid, chlorogenic acid, cinnamic acid, ferulic acid (phenolic acids), chrysin (flavone), myricetin, quercetin (flavonols), naringenin (flavanone). HPTLC on silica gel with chloroform – ethyl acetate – formic acid 5:4:1. Visualization under UV 254 nm and 366 nm, before and after derivatization by spraying with aluminium chloride (1 % in methanol), which rendered flavone bands bright yellow. Quantitative absorbance measuremet by densitometry at 366 nm. Linearity was in the range of 12,5–200 µg/mL for most standards (25–400 µg/mL for chrysin). Main differences observed in samples: 1) abscisic acid (hRF 56) and chrysin (hRF 82) were present only in Tilia honey samples, quercetin (hRF 55) only in Robinia honey; 2) ferulic acid (hRF 60) was the most prominent blue band in Tilia honey samples (1.35–18.73 g/kg of honey), and less intense in Robinia honey (0–1.24 g/kg of honey). Multivariate analysis was performed in two different ways with principal component analysis.

Drug Standards of China 22 (3), 259-264 (2021). Gentianella acuta (Michx.) Hulten is a herbal traditional Chinese medicine, containing mainly efficacy components like diphenylpyrione, cycloether terpenoids, flavonoids, and triterpenoids. It has liver protection, hypoglycemic, anti-inflammatory and other pharmacological activities, and is used clinically to treat jaundice, headache, fever, dry mouth and bile fever etc. To establish a quality standard of the herb, TLC was used for the investigation of the chemical composition and fingerprints. TLC of methanolic extracts of 10 batches of Gentianella acuta  collected from different regions (A) for cycloether terpene components (gentiopicroside and swertimarin), on silica gel with ethyl acetate - methanol - water 4:1:1, detection under UV 254 nm, identification by comparison of the fingerprints with those of the standards gentiopicroside and swertimarin; (B) for terpenoids (oleanolic acid), on silica gel with chloroform - methanol - ammonium hydroxide 20:6:1, detection under UV 254 nm, identification by comparison of the fingerprints with those of the oleanolic acid standard; (C) for aqueous extracts (water-soluble components such as flavonoids and phenolic acids), on silica gel with 1-butanol - acetic acid - water 9:3:2, detection by spraying with 5 % aluminium trichloride solution and evaluation under UV 366 nm, identification by comparison of the fingerprints with those of the oleanolic acid standard. The results showed that the TLC profiles of 10 batches were very similar, and well consistent with the HPLC fingerprint results. In addition, gentiopicroside, swertimarin and oleanolic acid were identified by TLC in the medicine, thus can be used as the target components of the identification. Therefore, the results of this study can be used as the basis for the authenticity identification and quality evaluation of the medicine.

Antioxidants, 10(1), 117 (2019). Samples were methanolic extracts of Camellia sinensis leaves or commercial black, white or green tea powdered extracts (Theaceae), as well as standards of caffeine (methylxanthine alkaloid), of flavonols (quercetin, rutin) and of flavanols (catechin, catechin-gallate, epicatechin, epicatechin-gallat, epigallocatechin, epigallocatechin-gallate, gallocatechin, and the thearubigin theaflavin). HPTLC on RP18-W phase (with classical irregular particles (SP1) vs. LiChrospher phase with spherical particles (SP2)), prewashed with methanol – water 4:1 and dried 20 min at 110 °C, developed with citric acid 0,295 % in acetonitrile – water 3:10 for SP1, with citric acid 0,17 % in acetonitrile – water 1:2 for SP2. Visualization under white light, UV 254 nm and 366 nm. Absorbance densitometry was performed at UV 275 nm (deuterium lamp). Derivatization with A) Fast Blue B salt reagent followed by 3 min heating at 100 °C, and by absorbance densitometry at 546 nm for flavanols (mercury lamp); B) natural product reagent (on the same plate), followed by fluorescence densitometry of flavonols at FLD 366/>400 nm (mercury lamp); C) anisaldehyde sulfuric acid reagent, followed by 2 min heating at 110 °C, to detect all flavonoids. Effect-directed analysis was performed using piezoelectric spraying: A) for free radical (DPPH•) scavengers (vs. gallic acid as positive control); B) for activity against Gram-negative Aliivibrio fischeri (bioluminescence assay, vs. caffeine) or Gram-positive Bacillus subtilis (vs. tetracycline); C) for enzymatic inhibition of acetyl-cholinesterase, α- and β-glucosidase, β-glucuronidase, tyrosinase (vs. rivastigmine, acarbose, imidazole, D–saccharolactone and kojic acid, respectively). When SP2 was used, previous neutralization was required through spraying of sodium bicarbonate buffer (2.5 %, pH 8). AChE inhibition assay was performed with indoxyl acetate (0.1 % in ethanol) as substrate, sprayed before the enzyme. After incubation (30min at 37°C), inhibition bands appeared indigo or blue under white light, but the substrate coloured theaflavin in yellow.

J Chromatogr A, 1605, 460371 (2019). HPTLC of toluene – ethyl acetate extracts of Primula boveana leaves and of P. veris (Primulaceae) on silica gel with n-hexane – ethyl acetate 7:3. Visualization under white light, UV 254 nm and 366 nm. Derivatization by spraying with anisaldehyde sulfuric acid reagent, followed by heating for 4 min at 105 °C. Effect-directed analysis: A) for activity against Gram-negative (Aliivibrio fischeri bioluminescence assay) or Gram-positive bacteria (Bacillus subtilis bioassay) using automated immersion; B) for enzymatic inhibition (acetyl- and butyryl-cholinesterase) using piezoelectric spraying, with rivastigmine as standard, and absorbance spectra (500 nm) for P. boveana active bands measured by inverse scanning. Active bands were eluted from the untreated layer with methanol through the oval elution head of a TLC-MS interface pump, into a quadrupole-Orbitrap mass spectrometer to record full scan mass spectra (m/z 100−1000) using electrospray ionization (ESI voltage 3.5kV for P. boveana, -3kV for P. veris, source temperature 250°C). With the further help of preparative HPLC – NMR, they were identified as linoleic and linolenic acids in P. veris, and as flavone and its derivatives: hydroxyflavone, methoxyflavone and zapotin, in P. boveana.