J Chromatogr A, 1675, 463167 (2022). Samples were ethanol extracts (and their flash chromatography fractions) of Prunus armeniaca leaves (Rosaceae), as well as betulinic, linolenic, maslinic (= crataegolic), oleanolic, ursolic acids and pygenic acids A (= corosolic acid) and B b as standards. When needed, to improve separation of triterpenoids, reversible pre-chromatographic derivatization was performed in situ by applying 10 µL iodine solution (2 % in chloroform) either before development on the deposit band, or for 2D-HPTLC after a first separation up to 60 mm and before a second orthogonal separation. Layers were covered 10 min with glass sheet after iodine application, and then dried 1 min under cold air stream. HPTLC on silica gel with chloroform – ethyl acetate – methanol 20:3:2, 85:9:6, or 15:2:3), followed by 5-10 min drying under cold air stream (eliminating iodine completely). Post-chromatographic derivatization by immersion (time 2 s, speed 3 cm/s) into vanillin – sulfuric acid (40 mg and 200µL, respectively, in 10 mL ethanol), followed by heating 5 min at 110 °C. Antibacterial effect-directed analysis was performed by immersion (time 8 s) into Bacillus subtilis suspension, followed by 2 h incubation at 37 °C, immersion in MTT solution and 30 min incubation at 37 °C. Active bands were eluted from layer with methanol through the oval elution head of a TLC-MS interface pump, into a single quadrupole mass spectrometer to record full scan mass spectra (m/z 200–1200 in both modes) using electrospray ionization (interface temperature 350°C, heat block temperature 400°C, desolvation line temperature 250°C, detector voltage 4.5kV). Five triterpenoids were identified: betulinic, corosolic, maslinic, oleanolic and ursolic acids, acid, as well as two fatty acids: linolenic and palmitic acid.

J. Planar Chromatogr. 35, 509-517 (2022). HPTLC of tamsulosin hydrochloride (1) and tolterodine tartrate (2) binary mixture on silica gel with ethyl acetate - n-hexane - diethylamine 9:3:1. Quantitative determination by absorbance measurement at 225 nm. The hRF values for (1) and (2) were 40 and 85, respectively. Linearity was between 10 and 200 ng/zone for (1) and 100 and 900 ng/zone for (2). The LOD and LOQ were 3 and 8 ng/zone for (1) and 22 and 66 ng/zone for (2), respectively. Average recovery was 100.1 % for (1) and 100.7 5 for (2).

J. Planar Chromatogr. 35, 519-532 (2022). HPTLC of binary mixtures of the novel oral anticoagulants (NOACs) apixaban (1), edoxaban tosylate (2) and rivaroxaban (3) with the lipid-lowering statin, rosuvastatin calcium (4) on silica gel with toluene - ethyl acetate - methanol - 25 % ammonia 35:45:20:2 (method 1) for the three mixtures, and methanol - 25 % ammonia 199:1 (method 2) for (2)/(3) mixture only. Quantitative determination by absorbance measurement at 291 nm. The hRF values for (1) to (4) were 65, 20, 75 and 10 using method 1, and 40 for (2) and 90 for (4) using method 2. Linearity was between 5 and 45 µg/mL for (1) to (4). Interday and intra-day precisions were below 3 % (n=6). The LOD and LOQ were 0.1 and 0.4 µg/mL for (1), 1 and 4 µg/mL for (2) and (3), 0.4 and 1 µg/mL for (4) using method 1, and 1.4 and 4.7 µg/mL for (2) and 0.4 and 1.2 µg/mL for (4) using method 2. Average recovery was between 97.6 and 102.9 % for (1) to (4).

J. Planar Chromatogr. 35, 481-490 (2022). HPTLC of oleo‑gum resin of raw and purified Commiphora wightii on silica gel with chloroform - ethyl acetate - formic acid - acetic acid
30:9:2:2. Detection by spraying with anisaldehyde sulfuric acid reagent, followed by heating at 105 °C until the development of visible zones. The plate was analyzed under UV light at 254 and 366 nm, and after derivatization at 541 nm. 

J. Planar Chromatogr. 35, 543-546 (2022). HPTLC of diazepam in spiked lemon juice drink on silica gel with chloroform - acetone 4:1 (system 1) and chloroform - methanol - ethyl acetate 14:3:1 (system 2). Detection under UV light at 254 nm. The hRF values for diazepam in systems 1 and 2 were 72 and 88, respectively. 

J. Planar Chromatogr. 35, 395-402 (2022). HPTLC of Padina boergesenii on silica gel with toluene - ethyl acetate 93:7. Detection by spraying with different reagents: anisaldehyde‒sulfuric acid reagent, vanillin‒sulfuric acid reagent, methanolic‒sulfuric acid reagent and Liebermann‒Burchard reagent (1 mL concentrated sulfuric acid, 20 mL acetic anhydride and 100 mL chloroform). Fingerprint analysis under UV light at 254 and 366 nm.

J. Planar Chromatogr. 35, 363-373 (2022). HPTLC of midazolam (1), prochlorperazine (2), citalopram (3) and chlorodiazepoxide (4) in urine on silica gel with cyclohexane - toluene - diethylamine 14:3:3. Quantitative determination by absorbance measurement at 229 nm for (1), 257 nm for (2), 240 nm for (3) and 275 nm for (4). The hRF values for (1) to (4) were 31, 79, 63 and 7, respectively. Linearity was between 3 and 7 µg/zone for (1) to (4). Interday and intra-day precisions were below 5 % (n=3). The LOD and LOQ were 0.5 and 1.6 µg/zone for (1), 0.7 and 2.1 µg/zone for (2), 0.5 and 1.6 µg/zone for (3) and (4).  Average recovery was 95.5 % for (1), 90.5 % for (2), 95.9 % for (3) and 92.5 % for (4).

J Chromatogr A, 1608, 460415 (2019). Samples were acetonitrile extracts of Annona cherimola fruit peel, pulp and seeds (Annonaceae), as well as caffeic acid as standards. HPTLC on silica gel with chloroform – ethyl acetate – propanol 21:2:2 for peel extracts, with chloroform – methanol 9:1 for seed extracts. Derivatization by spraying Dragendorff’s reagent for alkaloids, secondary amines and non-nitrogenous oxygenated compounds.  Effect-directed assay was performed for inhibitors of α-glucosidase. Before sample application, plates were developed with enzyme substrate (2-naphthyl-α-D-glucopyranoside 0.1 % in methanol) and dried 20 min at 60 °C. Then, samples were applied and separated, and mobile phase was removed by heating 10 min at 60 °C. The chromatogram was sprayed with 4 mL enzyme solution (5 unit/mL in 100 mM phosphate buffer,  pH 7.4), liquid excess was removed under lukewarm air stream, the plate was incubated 10 min at 37 °C in a moisture box, followed by spraying chromogenic reagent Fast Blue salt B 0.1 % in water, giving after 2 min white inhibition bands visible on purple background under white light. Plate image was documented under illumination (reflectance mode) with white light. The bands of 3 inhibiting compounds were analyzed in a triple quadrupole mass spectrometer. 1) Full scan mass spectra (m/z 50−1000) in the positive ionization mode were recorded using electrospray ionization (ESI, spray voltage 3 kV, desolvation line temperature 250 °C, block temperature 400 °C) for compounds directly eluted with methanol – acetonitrile through the oval elution head of a TLC-MS interface pump. 2) Compounds were also isolated (either eluted directly from the plate into a vial through the same interface, or scraped from the plate and extracted with methanol – chloroform into a vial), dried, and submitted to HPLC-DAD-MS/MS; MS-MS spectra were recorded in the same conditions, using argon as collision gas and collision cell voltages from -20 and -40 V. Inhibitors were identified as phenolamides (phenylethyl cinnamides): moupinamide (hRF 66 in peels, 56 in seeds), N-trans-feruloyl phenethylamine (hRF 76 in peels), N-trans-p-coumaroyl tyramine (hRF 44 in seeds).