J. of Chromatogr. A 1533, 180-192 (2018). HPTLC-UV/Vis/FLD-(bio)assay-HRMS of polar (phenolics) and nonpolar (tanshinones) extracts of Salvia miltiorrhiza Bunge root (Danshen), followed by streamlined scale-up to preparative layer chromatography with 1H-NMR. For phenolics, HPTLC on silica gel first with toluene - chloroform - ethyl acetate - methanol - formic acid 4:6:8:1:1 and second development with petroleum ether - cyclohexane - ethyl acetate 25:14:11. Confirmation of the acetylcholinesterase inhibitors salvianolic acid B (1), lithiospermic acid (2), rosmarinic acid (3), cryptotanshinone (4) and 15,16-dihydrotanshinone I (5). In the polar extracts, compounds (1), (2) and (3) exhibited free radical scavenging activity in the 2,2-diphenyl-1-picrylhydrazyl assay (DPPH* radical reagent), (4) and (5) were active against Bacillus subtilis and Aliivibrio fischeri (LOD of 12 ng/zone for (4), and 5 ng/zone for (5). For the first time, the unidentified, most active zone of the nonpolar Danshen extract was identified as a co-eluting zone of 1,2-dihydrotanshinone and methylenetanshinquinone 2:1.

J. Planar Chromatogr. 32, 475-479 (2019). TLC of enantiomers of (RS)-ketorolac on home-made silica gel plates impregnated with L-Tryp (1), L-Val (2), L-Met (3) or L-His (4) with acetonitrile - methanol - water - chloroform 9:5:2:4 for (1), acetonitrile - methanol - water - dichloromethane 6:2:1:1 for (2), acetonitrile - methanol - water - chloroform 5:3:1:1 for (3) and acetonitrile - methanol - water - chloroform 10:4:1:5 for (4), respectively. Detection by exposure to iodine vapors. The hRF values for (S)-(‒)- and (R)-(+)-ketorolac were 36 and 81 for (1), 30 and 79 for (2), 30 and 87 for (3) and 42 and 85 for (4), respectively. LOD was 0.4 μg/mL.

J. Planar Chromatogr. 32, 447-451 (2019). HPTLC of Fritillaria cirrhosa on silica gel with ethyl acetate - methanol - ammonia solution - water 180:20:10:1. Bioautography by dipping into a 0.15 mg/mL solution of substrate Gly-Pro-p-nitroanilide hydrochloride in 50 % of ethanol, followed by ethanol removal in the hood and dipping into a 10 U/L DPP IV enzyme solution in TrisHCl buffer (pH 8.2, 70 mM), followed by incubation at 37°C for 40 min. Detection by dipping into a solution of 0.5 % sodium nitrite in 1.2 M hydrochloric acid, followed by drying slightly for 5 min and dipping into 0.05 % N-(1-naphthyl)ethylenediamine dihydrochloride solution. Further analysis by mass spectrometry using a TLC interface. The hRF value for the dipeptidyl peptidase IV inhibitor was 58.

J. Planar Chromatogr. 32, 411-420 (2019). HPTLC of oleuropein in olive leave samples belonging to 9 different Egyptian olive varieties on RP-18 with methanol - acetonitrile 7:3. Detection by dipping into a methanolic 2-aminoethyldiphenylborane reagent (0.5 %), followed by drying and dipping into methanolic PEG 400 solution (5 %). Qualitative determination under UV light at 366 nm. Captured images were processed using the ImageJ software in order to build 2 separate data matrices (before and after derivatization). Quantitative determination by absorbance measurement at 240 nm. The hRF value for oleuropein was 35. Linearity was between 0.1 and 0.6 µg/zone.  Intermediate precision was below 1 % (n=6). The LOD and LOQ were 0.07 and 0.22 µg/zone. Recovery rate was 100.5 %.

J. Planar Chromatogr. 32, 517-520 (2019). HPTLC of tramadol (1), caffeine (2), paracetamol (3), ibuprofen (4), naproxen (5), and diclofenac (6) on RP-18 WF, LiChrospher RP-18 WF, and RP-18 WF with concentration zone, developed with various ratios of methanol in water with 0.1 M potassium chloride. Qualitative identification under UV light at 254 nm. Potassium chloride may be used to suppress ion–ion interactions between the solutes and the silica gel surface.  HPTLC RP-18WF plates with concentration zone and developed with methanol - water 13:7 with addition of 0.15 mol/L KCl were suitable for the qualitative and quantitative analyses of tramadol, paracetamol, caffeine, naproxen, and ibuprofen or diclofenac. The method allowed to study subtle differences in the efficiency of the separation of analgesic drugs by HPTLC with similar octadecyl silica-based adsorbents.  

J. Planar Chromatogr. 32, 359-364 (2019). HPTLC of Schizonepeta annua on silica gel with chloroform - toluene - acetic acid 600:100:3. Detection by spraying with 5 % vanillin - sulfuric acid reagent (mixture of 2.5 g vanillin, 45 mL ethanol, and 5 mL concentrated sulfuric acid), followed by heating at 105 °C for 5 min. Antibacterial assay was performed by dipping the plate into a cell suspension culture (Brain heart infusion broth and brain heart infusion agar in the ratio of 9:1), followed by incubation at 35 °C for 16 h and immersion into 0.2 % MTT solution for 3s, followed by incubation at 35 °C for 3h. Plates were scanned at 546 nm. The hRF values for thymol and carvacol were 88 and 78, respectively.

J. Planar Chromatogr. 32, 435-437 (2019). HPTLC of glyphosate in biological material (viscera, liver, spleen, kidney and lungs) on silica gel with methanol - ammonia 9:1. Detection by spraying with chromogenic reagent (2.0 g cobalt(II) chloride and 3.0 g ammonium thiocyanate in 100 mL distilled water). The hRF value for glyphosate was 46. LOD was approximately 3 µg. Recovery rate was 100.2 % for (1), 100.1 % for (2) and 99.9 % for (3).

J. Planar Chromatogr. 32, 411-420 (2019). HPTLC of fosinopril sodium (1), hydrochlorothiazide (2), and chlorothiazide (3) on silica gel with ethyl acetate - chloroform - methanol - formic acid 120:80:10:1. Quantitative determination by absorbance measurement at 215 nm. The hRF values for (1) to (3) were 53, 39 and 29, respectively. Linearity was between 1 and 10 µg/zone for (1), 0.2 and 3 µg/zone for (2) and 0.2 and 2 µg/zone for (3).  Intermediate precisions were below 2 % (n=6). The LOD and LOQ were 280 and 860 ng/zone for (1), 90 and 350 ng/zone for (2) and 50 and 160 ng/zone for (3). Recovery rate was 100.2 % for (1), 100.1 % for (2) and 99.9 % for (3).