J. AOAC Int. 102, 708-713 (2019). TLC of snake bile in 20 species from three families (Elapidae, Colubridae, and Viperidae) on silica gel with xylene – isopropanol – methanol – glacial acetic acid – water 80:40:30:20:3. Detection by spraying with a 10% sulfuric acid ethanol solution, followed by heating at 105 ºC.  Qualitative identification under UV light at 366 nm. TLC coupled with quadrupole–time-of-flight–MS analysis of each zone was used for compound identification and evaluation.

J. AOAC Int. 102, 714-719 (2019). HPTLC fingerprint of the aerial parts of Isodon lophanthoides (Buch. Ham. ex D. Don) Hara (IL) on silica gel with toluene - chloroform - ethyl acetate - formic acid 30:10:10:1. Detection by spraying with 10 % sulfuric acid in ethanol, followed by heating at 105 ºC. Among the 12 bands with good resolution, four ursane-type triterpenoids were recognized as ursolic acid (hRF 61), 2α-hydroxy-12-en-28-ursolic acid (hRF 25), 2α,19α-dihydroxy-12-en-28-ursolic acid (hRF 19), and 2α-O-β-D-glucoside-12-en-28-ursolic acid (hRF 3). The method allowed to distinguish Isodon lophanthoides from its substitute, I. lophanthoides var. gerardianus and was a prospect for the quality control of I. lophanthoidis herba.

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. AOAC Int. 102, 726-733 (2019). HPTLC of different parts of Alpinia offcinarum on silica gel with n-hexane - ethyl acetate - acetic acid 6:1:1. Antioxidant activity analysis by spraying with methanolic 0.04 % 2,2-diphenyl-1-picrylhydrazyl (DPPH*) radical reagent, followed by densitometric detection at 535 nm. Zones were scraped from HPTLC plates and further analyzed by electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS). The method allowed the identification of three antioxidant compounds: (5R-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-heptanone, kaempferide, and galangal with hRF values of 21, 33 and 40, respectively.

J. Liq. Chromatogr. Relat. Technol. 42, 324-329 (2019). HPTLC of individual pharmaceutical products containing moxifloxacin HCl (1), ofloxacin (2), amoxicillin trihydrate (3), acetylsalicylic acid + acetaminophen + caffeine (4), nimesulide (5), irbesartan (6), and pantoprazole (7) on silica gel with methanol - ammonium hydroxide - water 7:2:1 for (1), methanol - ethyl acetate - ammonium hydroxide 7:7:3 for (2), acetone - water - methanol - glacial acetic acid 20:10:5:2 for (3), ethyl acetate - glacial acetic acid 19:1 for (4), toluene - acetone 10:1 for (5), ethyl acetate - acetone - glacial acetic acid 180:40:1 for (6) and ethyl acetate - methanol - toluene 4:1:2 for (7). Quantitative determination by absorbance measurement at 366 nm. The hRF values for (1) to (3) and (5) to (7) were 72, 30, 80, 33, 40 and 43, respectively. The hRF values for (4) were 62 for acetylsalicylic acid, 49 for acetaminophen and 22 for caffeine. The quantitative methods were used to transfer the Global Pharma Health Fund (GPHF) Minilab Manual and U.S. Food and Drug Administration (FDA) Compendium to HPTLC following a model process for moxfloxacin HCl, ofloxacin, and amoxicillin trihydrate. The results met the guidelines of the model process regarding the calibration curves: r-values were at least 0.99, assays were within 85–115% specification limits of the label values of individual tablets and capsules, validation recoveries were within 95 - 105 % at all three spike levels, RSDs were no higher than 3 % for assays and validation analyses, and peak identity and peak purity checks had correlation factors of at least
0.99. 
 

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, 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.