Journal Chromatogr A, 1641, 461727 (2021). HPTLc of an ethanolic maceration of Solidago gigantea roots (Asteraceae) on silica gel with n-hexane – isopropyl acetate – acetone 16:3:1, or n-hexane – isopropyl acetate – acetic acid 40:9:1. With the second mobile phase, acid residues had to be eliminated by 20 min automated drying or by 2 h incubation with potassium hydroxide in the opposite twin trough (followed by 15 min cold air streaming); this latter mobile phase allowed to obtain higher hRF values, but some butyrylcholinesterase (BChE) inhibiting activities were lost. The chromatograms were documented at UV 254 nm and 365 nm and white light before and after A) derivatization with vanillin – sulfuric acid reagent; B) enzymatic reaction by immersion into acetylcholinesterase, BChE, glucosidase and amylase solutions; C) Aliivibrio fischeri and Xanthomonas euvesicatoria bioassays, to detect activity against Gram-negative bacteria; D) Bacillus subtilis bioassay to detect activity against Gram-positive bacteria; E) a new antifungal assay with Fusarium avenaceum. For this assay, the chromatograms were immersed 6 s into the isolated mycelium suspension (diluted to OD600 0.4-0.8) and incubated in a vapor chamber at 21 °C for 48-72 h. Inhibition zones were indicated by the lack of visible white fungal hyphae. An aqueous solution of iodonitrotetrazolium (INT, 1 mg/ml) was sprayed on the plate to enhance the contrast (bright zones on a purple background). Benomyl (a benzimidazole fungicide) was used as positive control. Eight clerodane diterpenes (including kingidiol, hautriwaic lactone, and solidagoic acids A and B) were identified from six multipotent zones by bioassay-guided purification through preparative flash chromatography and HPLC, followed by HRMS and NMR, as well as by HPTLC hyphenated to quadrupole-orbitrap HRMS: A) by eluting with methanol (flow 100 µL/min) the compounds from the plate through the oval elution head of an interface of heated electro-spray ionization (spray voltage 3.5 kV, capillary temperature 270 °C, nitrogen as sheath and auxiliary gas, full scan in negative and positive ionization modes in m/z range 50-750); B) without eluent with a DART interface (Direct Analysis in Real-Time, needle voltage 4 kV, grid voltage 50 V, helium as gas, temperature 500 °C, full scan in positive ionization mode in m/z range 100-750).

J. Planar Chromatogr. 35, 181-187 (2022). HPTLC of gallic acid (1) and gallic acid ester (2) in Turkish gall on silica gel with dichloromethane - ethyl acetate - formic acid 5:3:1. Detection by spraying with 2 % ferric chloride ethanol solution. Quantitative determination by absorbance measurement at 280 nm. The hRF values for (1) and (2) were 67 and 81, respectively. Linearity was between 507 and 3045 ng/zone for (1) and 499 and 2994 ng/zone for (2). Interday and intra-day precisions were below 2 % (n=6). Average recovery was 100.6 % for (1) and 97.8 % for (2). The method was used to analyze the changes in the content of components which was treated by static simulated gastrointestinal digestion.

J. Planar Chromatogr. 35, 169-179 (2022). HPTLC of arjungenin (1) and arjunetin (2) in the bark of Terminalia arjuna on silica gel with toluene - ethyl acetate - formic acid 5:4:1. Detection by spraying with 10 % solution of sulfuric acid dissolved in methanol. Quantitative determination by absorbance measurement at 420 and 475 nm for (1) and (2). The hRF values for (1) and (2) were 43 and 67, respectively. Linearity was between 100 and 1000 ng/zone for (1) and (2). The method facilitated the detection of traces amount of adulterants in herbal products.

J. Planar Chromatogr. 35, 153-159 (2022). HPTLC of glucuronic acid in gum samples of Sterculia urens on silica gel with 1-propanol - water 7:3. Detection by spraying with napthoresorcinol sulfuric acid reagent, followed by heating at 105 °C for 5 min. Quantitative determination by absorbance measurement at 580 nm. The hRF value for glucuronic acid was 43. Linearity was between 300 and 700 ng/zone. Interday and intra-day precisions were below 2 % (n=3). Recovery was between 100.4 and 102.3 %.

J. Planar Chromatogr. 35, 161-167 (2022). HPTLC of catechin in the seeds of Parkia roxburghiion silica gel with ethyl acetate - acetic acid - formic acid - water 40:4:3:4. Quantitative determination by absorbance measurement at 302 nm. The hRF value for catechin was 61. Interday and intra-day precisions were below 1 % (n=3). The LOD and LOQ were 12 and 37 ng/zone, respectively. Recovery was found in the range of 99.1-99.5 %.

J. Planar Chromatogr. 35, 139-151 (2022). HPTLC of diosgenin in Costus speciosus on silica gel with n-hexane - ethyl acetate 7:2. Detection by spraying with anisaldehyde  -sulfuric acid (0.5 mL anisaldehyde in 1 mL of 97 % sulfuric acid), followed by drying at 105 °C. Quantitative determination by absorbance measurement at 440 nm. The hRF value for diosgenin was 23. Linearity was between 0.1 and 0.7 µg/zone. The LOD and LOQ were 0.84 and 2.55 µg/zone. 

J. Planar Chromatogr. 35, 3-12 (2022). HPTLC of alisol B 23-acetate (1), alisol B (2), alisol A (3) and alisol C 23-acetate (4) in the rhizomes of Alisma orientale on silica gel with cyclohexane - ethyl acetate 1:1. The hRF values for (1), (4), (2) and (3) were 62, 42, 28 and 9, respectively Quantitative determination by absorbance measurement at 254 nm for (1) and 208 nm for (2), (3) and (4). Linearity was between 125 and 2000 μg/zone for (1) and 83 and 2000 μg/zone for (2), (3) and (4). Interday and intra-day precisions were below 1 % (n=3). Average recovery was 94.2 % for (1), 90.3 % for (2), 97.0 % for (3) and 90.2 % for (4).

J. Planar Chromatogr. 34, 481-492 (2021). HPTLC of cynaroside (1), apiin (2), diosmin (3) and linarin (4) in Ziziphora clinopodioides on silica gel with ethyl acetate - dichloromethane - ethanol - formic acid - water 10:13:6:2:4. Quantitative determination by absorbance measurement at 350 nm. The hRF values for (1) to (4) were 30, 36, 45 and 60, respectively. Linearity was between 0.05 and 0.35 μg/zone for (1), 0.02 and 0.14 μg/zone for (2), 0.15 and 0.60 μg/zone for (3) and 0.05 and 0.70 μg/zone for (4). Interday and intra-day precisions were below 5 % (n=6). The LOD and LOQ were 5 and 16 ng/zone for (1) and (2), 150 and 500 ng/zone for (3) and 10 and 33 ng/zone for (4), respectively. Average recovery was 98.9 % for (1), 100.7 % for (2), 98.8 % for (3) and 100.2 % for (4).