Front. Pharmacol. 13, 925298 (2022). HPTLC of milk thistle on silica gel with toluene - ethyl formate - formic acid 8:10:1. Detection by dipping in NP reagent and subsequently in PEG reagent, followed by heating at 100 °C for 5 min. Qualitative analysis under UV light at 254 and 366 nm. HPTLC of alkylamides in coneflower on silica gel with ethyl acetate - ethyl methyl ketone - water - formic acid 5:3:1. Detection by dipping in NP reagent and subsequently in PEG reagent, followed by heating at 100 °C for 5 min. Qualitative analysis under UV light at 254 and 366 nm. HPTLC of black cohosh on silica gel with toluene - ethyl formate - formic acid 5:3:2. Detection by dipping into sulfuric acid reagent (20 mL of sulfuric acid in 180 mL of methanol), followed by heating at 100 °C for 5 min. 

Front. Pharmacol. 12, 678611 (2021). HPTLC of withanolide S in Withania somnifera and myristicin in Myristica fragrans on silica gel with toluene - ethyl acetate - acetic acid 5:4:1. Detection of myristicin under UV 254 nm. Detection of withanolide S by spraying with 5 % anisaldehyde sulfuric acid, followed by visualization under UV 540 nm. Screening of anticholinesterase active metabolites by spraying with DTNB/ATCI reagent (1 mmol/L 5,5-dithiobis-(2- nitrobenzoic acid) and 1 mmol/L acetyl thiocholine iodide). 

Anal. Bioanal. Chem. 414, 4167-4178 (2022). HPTLC of organothiophosphates malathion, parathion, and chlorpyrifos in storm, waste, and surface water on silica gel with an eluent mixture of cyclohexane, dichloromethane, and acetone in different proportions and with increasing migration distances. The plate was sprayed with n-bromosuccinimide to oxidize the organothiophosphates. AChE‑inhibition assay was performed by spraying with an AChE solution, followed by incubation at 37 °C for 5 min. Plates were sprayed with the substrate indoxyl acetate freshly prepared in methanol, followed by incubation for 45 min at room temperature. Detection at 670 nm using the fluorescence mode. 

Anal. Bioanal. Chem. 414, 5991-6001 (2022). 2D-HPTLC fingerprint of Alpinia officinarum on silica gel in 384-well microplate array format (4.5 × 4.5 mm) matrix with trichloromethane - methanol - petroleum ether 97:3:25 in the first dimension and ethyl acetate - petroleum ether - acetic acid 15:35:1 in the second dimension. The paired chromatographic-based microassay array with the consistent chromatographic distribution was prepared by transferring a portion of the sample from the stock chromatographic-based microassay arrays to the corresponding array units of another 384-well microplate. A G‑quadruplex ligand bioassay was used to evaluate the ligand activity of the components in each array unit of the chromatographic-based microassay array. Further analysis by mass spectrometry. 

Anal. Bioanal. Chem. 414, 4481-4495 (2022). HPTLC of selected caffeine-containing standards and beverages (Red Bull, Coca-Cola, coffee, and black tea) on different stationary phases (silica gel, RP- and cyano-) with propan-2-ol - n-heptane - water 7:3:1. Direct surface analysis of the TLC plates with a flowing atmospheric pressure afterglow (FAPA) ambient desorption/ionization source (TLC-FAPA-MS). CN-HPTLC plates were the most efficient stationary phase, resulting in a significantly more intense caffeine signal.

Pharmacogn. Mag. 18, 836-843 (2022). HPTLC of shatavarin IV in the roots of Asparagus racemosus on silica gel with ethyl acetate - methanol - water 15:3:2. Detection by dipping into anisaldehyde-sulfuric acid reagent, followed by heating at 110 °C for 5 min. Quantitative determination by absorbance measurement at 425 nm. The hRF value for hatavarin IV was 40. Linearity was between 72 and 432 ng/zone. Intermediate precisions were below 2 % (n=3). The LOD and LOQ were 24 and 72 ng/zone, respectively. Mean recovery was 97.5 %.

Rapid Commun. Mass Spectrom. 36, e9409 (2022). HPTLC of nicotinamide, 2-phenylacetamide, and dibenzylamine on silica gel with toluene - acetone - methanol - ammonia 8:9:2:1. Flame-induced atmospheric pressure chemical ionization (FAPCI) was used to directly characterize chemical compounds on a glass rod and drug tablet surfaces and applied as an interface TLC and mass spectrometry (MS) for the analysis of the mixture. The LOD of nicotinamide, 2-phenylacetamide, and dibenzylamine was between 5 and 50 ng/zone. 

J. Sep. Sci. 45, 1305-1316 (2022). HPTLC of tamsulosin hydrochloride (1) and solifenacin succinate (2) along with their impurities on silica gel with ethyl acetate - butanol - glacial acetic acid 100:4:1. Quantitative determination by absorbance measurement at 225 nm. The hRF values for (1) and (2) were 61 and 26, respectively. Linearity was between 0.1 and 1.0 µg/zone for (1) and 1.0 and 15.0 µg/zone for (2). Inter-day and intra-day precisions were below 2 % (n=6). Mean recovery was 99.9 % for (1) and 99.8 % for (2).