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, 431-434 (2022). HPTLC of carbaryl in biological material on silica gel with hexane - acetone 4:1. Detection by spraying with reagent A (4 g sodium hydroxide in 100 mL water), waiting for 10 min, followed by spraying with reagent B (2 g vanillin in 100 mL acetone). Brown-colored zone with white background was clearly visible. The hRF values for carbaryl were 22 and 54.

J. Planar Chromatogr. 35, 281-285 (2022). HPTLC of vanillin (1) and ethyl vanillin (2) in flavoring agents on silica gel with toluene - chloroform - acetone 7:8:2. Detection under UV light at 254 and 366 nm. The hRF values for (1) and (2) were 46 and 55, respectively.

J. Planar Chromatogr. 35, 299-311 (2022).  HPTLC of powdered herbal drugs and finished products (leaves of Mentha piperita, Olea oleuropea, Ginkgo biloba and Camellia sinensis, fruits of Styphnolobium japonicum and Piper nigrum, roots of Angelica species (A. gigas, A. sinensis, A. dahurica, A. acutiloba, and A. pubescens, Curcuma longa and poly-herbal products containing powdered extracts of Curcuma longa root and Piper nigrum fruits) on silica gel with three complementary developing solvents (CDS): low polar developing solvent (toluene - ethyl acetate 9:1); medium polar developing solvent (cyclopentyl methyl ether - tetrahydrofuran - water - formic acid 40:24:1:1); and high polar developing solvent (ethanol - dichloromethane - water - tetrahydrofuran 16:16:4:1). Detection by heating at 100 °C for 3 min, followed by spraying with NP reagent (1.0 g of 2-aminoethyl diphenylborinate in 100 mL of methanol). For Olea oleuropea and Ginkgo biloba, the derivatization with NP was followed by spraying with anisaldehyde sulfuric acid reagent and heating at 100 °C for 3 min. Analysis was performed under UV light at 254 and 366 nm. Performance of the Universal HPTLC mix (UHM) was assessed in terms of precision. The hRF values for all substances were between 20 and 80. 

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).

J. Planar Chromatogr. 35, 313-330 (2022).  HPTLC of orange peel extract on silica gel with gradient multiple development using seven different polarity ranges: cyclohexane, cyclohexane - n-heptane 3:7, cyclohexane - methyl tert-butyl ether 43:7, cyclohexane - methyl tert-butyl ether 7:3, cyclohexane - methyl tert-butyl ether 3:7, methyl tert-butyl ether, methyl acetate - ethanol 9:1, ethyl acetate - ethanol - formic acid 44:5:1. Detection by spraying with vanillin reagent (100 mg vanillin dissolved in 9.8 mL ethanol and 0.2 mL sulfuric acid), followed by heating at 100 °C for 2 min. DPPH staining was performed with 2 mL of a DPPH solution (15 mg dissolved in 10 mL of methanol). Bioautography was performed by dipping into Aliivibrio fischeri bacteria suspension for 6 s, followed by measurement of bioluminescence within 15 min. In this sample, more than 50 compounds could be separated.

J. Planar Chromatogr. 35, 243-250 (2022). Micro TLC of three dyes (1-aminoanthraquinone, fat green and 2-nitroaniline) on silica gel with toluene at distances 1, 1.5, 2, 2.5, or 3 cm. Experiments were performed using a prototype device operated at a controlled velocity of the mobile phase, where the chromatographic plate was placed in the chamber with the adsorbent layer face-down and the mobile phase was delivered onto the adsorbent layer of the chromatographic plate by the pipette, which was driven into movement by a 3D machine controlled by a computer. Different solvents (acetone, methanol, toluene, or heptane) were used to wet and to narrow the starting zones. Detection under UV light at 286 nm. To take full advantage of the benefits of micro-planar chromatography, the size of the starting zone should be reduced as well as the processes
related to the dissolution kinetics of the starting zones of substances in the mobile phase should be optimized.
 

J. Planar Chromatogr. 35, 229-241 (2022). Review of the advances, limitations and challenges faced by the application of HPTLC for lipidomic analysis. The paper described methods for the separation of phospholipids (PL) and/or sphingolipids (SL) on silica gel HPTLC plates from different samples in lipidomic studies, including matrices and development conditions. HPTLC methods for separating lipid classes and subclasses, combined with semi-quantification by UV‒FL densitometry and mass spectrometry were also described. HPTLC and genetic knockouts was also discussed as an emerging field.