J. Liq. Chromatogr. Relat. Technol. 41, 1052-1065 (2019). Review of the following topics for the period of November 1, 2016 to November 1, 2018: sample preparation for TLC pesticide analysis; lipophilicity and retention studies for the study of biological activity; new reagents for pesticide detection; HPTLC-effect directed analysis on the surface of the layer; TLC-Raman spectrometry for the analysis of thiabendazole, triazophos, and phosmet residues; TLC analysis of radiolabeled pesticides; methods for the separation, detection, and qualitative and quantitative determination of pesticide residues; determination of pesticides in commercial products and the use of TLC for pesticide degradation studies. The review highlighted the isolation, characterization, and determination of less hazardous and less toxic biopesticides from plants, bacteria, fungi, and soil as the most active application area of pesticide TLC today.

J. Liq. Chromatogr. Relat. Technol. 42, 249-257 (2019). HPTLC of methanolic extracts from the leaves of Paulownia tomentosa on silica gel with chloroform - ethyl acetate - methanol 20:3:2. HPTLC-direct bioautography by dipping into B. subtilis cell suspension, followed by incubation at 28 °C for 2 h. Then the bioautograms were dipped into an aqueous solution of the MTT vital dye (1 mg/mL (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide), followed by incubation at 28 °C for 30 min. Further analysis by using a HPLC-DAD-MS system allowed the identification of apigenin and p-coumaric acid as highly abundant antibacterial components.

J. Liq. Chromatogr. Relat. Technol. 42, 122-127 (2019). Review of the application of TLC and HPTLC for the analysis of Licorice, the dried root and rhizome of Glycyrrhiza uralensis Fisch., Glycyrrhiza inflate Bat., or Glycyrrhiza glabra L. The authors described methods using HPLC combined with HPLC fingerprint for rapid identification of species as well as methodologies for the analysis of glabridin on silica gel and RP-18.

J. Liq. Chromatogr. Relat. Technol. 42, 238-248 (2019). Review of recent applications of TLC in medicinal chemistry, including the determination of lipophilicity of biologically active compounds and its influence as activity descriptors of absorption, distribution, metabolism, elimination and toxicity. Practical applications of TLC as a fast screening technique in different stages of monitoring processes were also described, including systems recently used for stability studies of selected drugs.

J. Liq. Chromatogr. Relat. Technol. 42, 266-273 (2019). HPTLC of aqueous, fermented plant preparations from Chamomilla recutita L. (1), Allium cepa L. (2), Equisetum arvense L. (3) and Hamamelis virginiana L. (4) of different harvest years on silica gel with ethyl acetate - toluene - formic acid - water 16:4:3:2. The method was combined with effect-directed analysis (EDA) and high-resolution mass spectrometry (HRMS). For α-/β-glucosidase assays, the plate was sprayed with 2 mL substrate solution (60 mg 2-naphthyl-α-D-glucopyranoside or 2-naphthyl-β-D-glucopyranoside in 50 mL ethanol), then sprayed with 1 mL sodium acetate buffer and 2 mL enzyme solution (500 units α-glucosidase), followed by incubation at 37 ºC for 10 min. Analysis of multi-potent compounds was also performed using the 2,2-diphenyl-1-picrylhydrazyl reagent and Gram-positive Bacillus subtilis assays, followed by recording of elution head-based HPTLC-ESI-HRMS spectra. 

J. Liq. Chromatogr. Relat. Technol. 42, 311-316 (2019). HPTLC of equol in cattle manure with methyl t-butyl ether - cyclohexane 1:1. The plate was scanned with a Time of Flight – Direct Analysis in Real Time – Mass Spectrometry (TOF-DART-MS) system. The hRF value of equol was 71. The LOD and LOQ for equol were 2.4 µg/zone and 4.5 µg/zone, respectively. 

J. Liq. Chromatogr. Relat. Technol. 32, 41-46 (2019). HPTLC of flavonoids apigenin, luteolin, chrysin, myricetin, prunin (or naringenin 7-O-glucoside), nicotiflorin (or kaempferol 3-O-rutinoside), rutin (or quercetin 3-O-rutinoside), quercetin 3-O-glucopyranoside, luteolin 7-O-glucoside, isovitexin (or apigenin-6-C-glucoside), apigenin-7-O-glucoside, naringenin, hesperetin, flavone, kaempferide, kaempferol, naringin, hesperidin, quercetin dihydrate and quercetin in Caigua (Cyclanthera pedata Scrabs) on silica gel (1) or RP-18 (2) with ethyl acetate - water - formic acid 17:3:2 for (1) or 5 % formic acid in methanol - water 7:3 for (2). Detection by heating at 110 ºC, followed by dipping into Natural product reagent for 2 min. Qualitative identification under UV light at 254 nm and 366 nm. Flavonoids were further analyzed by HPTLC–MS/(MSⁿ). 

Planta Med. 83(14/15), 1233-1241 (2017). HPTLC of standards and methanolic extracts of L. cardiaca, L. japonicus and L. sibiricus (Lamiaceae) acidified with formic acid on silica gel with ethyl acetate – acetic acid – formic acid – water 100:11:11:26, in an automatic development chamber with 48 % humidity (20 min presaturation). Detection under white and UV light, before and after immersion in 1) anisaldehyde – sulphuric acid (followed by heating) for the detection of iridoids; 2) natural product reagent A for phenylpropanoids; 3) modified Dragendorff reagent (bismuth oxynitrate 0.17 %, sulfuric acid 3.5 %, glacial acetic acid 2 %, potassium iodide 4 %) for alkaloids. Ajugoside (hR_F 29) and verbascoside (hR_F 53) were found in L. cardiaca and L. sibiricus, but absent in L. japonicus. The opposite was true for leonurine (hR_F 52), whereas stachydrine (hR_F 14) was found in the three species. This method allows to distinguish L. japonicus from the other species, which have to be distinguished from each other through morphology.