J. AOAC Int. 102, 720-725 (2019). HPTLC fingerprint of 98 batches of four commonly used traditional Chinese medicines dried tangerine peel (Chen Pi), green tangerine peel (Qing Pi), immature bitter orange fruit, and bitter orange fruit (Zhi Qiao) from two similar Citrus spp on silica gel with chloroform - methanol - water - acetic acid 26:8:2:3. Detection by spraying with 5 % aluminum chloride in ethanol, followed by examination under UV light at 366 nm. Artificial neural network analysis was applied to raw HPTLC fingerprints without any image processing and by manual image processing followed by chemometrics modeling (k-nearest neighbors and partial least-square discriminant analysis).

J. Liq. Chromatogr. Relat. Technol. 42, 1-8 (2019). HPTLC of phospholipids  (phosphatidylcholines, phosphatidylethanolamines, cardiolipins and phosphatidylglycerols) associated to membrane proteins in Rhodobacter (Rb.) blasticus, Rhodospirillum (R.) rubrum and Rhodobaca (Rbc.) bogoriensis on silica gel with a 7-step gradient based on methanol - water - ethyl acetate. HPTLC was coupled to electrospray mass spectrometry (ESI-MS) using an elution head-based interface for the identification of several phospholipid species.

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, 249-257 (2019). Review of HPTLC methods published after 2000 for the analysis of vegetables, including bioactive compounds such as indoles, glycolipids, carotenoids and anthocyanins. TLC methods for the identification and quantification of pesticide residues such as iprodione, vinclozolin, cymoxanil, deltamethrin and parathion were reviewed. TLC coupled with other non-chromatographic techniques for the analysis of inorganic species, mycotoxins, glycoalkaloids and polyamides was described.  

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. 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). 

J. Planar Chromatogr. 32, 335-338 (2019). TLC of paraquat on silica gel with methanol - ammonia 97:3. Detection by spraying with 1 % phenylhydrazine (0.5 g phenylhydrazine in 50 mL 2 N sodium hydroxide). The hRF value of paraquat was 62.