J. Chromatogr. A 1526, 137-150 (2017). HPTLC of physalins from crude extracts of Chinese lantern (Physalis alkekengi L.) on silica gel with ethyl acetate – toluene – formic acid 35:15:1. Densitometric screening of physalins in absorption and in fluorescence mode after post-chromatographic derivatization with sulfuric acid reagent. Identification of the physalin L standard and its impurity, 2,3,25,27-tetrahydrophysalin A. Applying two successive plate pre-developments with methanol – formic acid 9:1 and methanol to avoid strong ion suppression caused by the developing solvent additive (formic acid), and to improve the sensitivity of HPTLC-MS/MS method combined with a slightly modified developing solvent ethyl acetate – toluene – formic acid 30:20:1. Non-targeted characterization of physalins from the same chromatographic zone and determination of physalin types by simultaneous hyphenation of HPTLC with a triple quadrupole and an ion trap mass analyzer. Demonstration of the performance of the HPTLC-densitometric and HPTLC–MS/MS methods for the analysis of physalins from aqueous reflux extracts. Observation of variations in physalin profiles and abundances in different parts of P. alkekengi harvested at different stages of maturity, showed that the husks are the most suitable plant part for P. alkekengi quality control.

J. Planar Chromatogr. 31, 72-78 (2018). HPTLC of equol in ethanolic cattle manure extract on RP-18 with n-hexane – ethyl – acetate – acetone 9:3:2. Detection by planar yeast estrogen screening (pYES) by dipping into a yeast suspension, followed by incubation at 30 °C for 4 h. After incubation, the plate was dried in a 37 °C incubator for 15 min and dipped into the combined reaction buffer followed by incubation at 37 °C for 60 min and 90 % relative humidity. The combined reaction buffer was prepared by mixing 20 mL of buffer C (5.3 g of sodium phosphate dibasic and 0.4 g of potassium chloride were dissolved in about 490 mL water, the solution was adjusted with sodium hydroxide to pH 13, 0.5 g of benzalkonium chloride were added and the mixture was filled up to 500 mL) and 0.2 mL of a freshly prepared X-Gal solution (0.05 g/mL X-Gal in DMSO). Fluorescence evaluation under UV 366 nm. The hRF value for equol was 47.

J. AOAC Int. 99, 1204-1212 (2016). HPTLC of St. John’s wort labeled as Hypericum perforatum on silica gel with ethyl acetate – dichloromethane – formic acid – acetic acid – water 100:25:10:10:11 (USP 38-NF33), ethyl acetate – formic acid – water 30:2:3 (European Pharmacopoeia) and ethyl acetate – acetic acid – formic acid – water 100:11:11:26 (USP 37-NF32). For the investigation of synthetic dyes, samples were analyzed on RP-18 with methanol – 5 % aqueous sodium sulfate 3:4. Detection by dipping into natural products reagent (1 g diphenylborinic acid 2-aminoethylester in 200 mL ethyl acetate), then in polyethylene glycol reagent (10 g PEG 400 (macrogol) in 200 mL dichloromethane). Qualitative identification under UV 254 and 366 nm. A decision tree was developed to analyze adulterated samples labeled as Hypericum perforatum. If for example under UV 366 nm after derivatization a yellow fluorescent zone is seen at hRF 46, samples are probably mixed with another undesired species. In addition, if a bluish zone is seen at application position of samples identified with the test USP 38-NF32 and examined under white light prior derivatization, the sample is probably mixed with dyes.

Food Chem. 255, 120-131 (2018). HPTLC of polyphenols (chlorogenic acid and rutin) in the peel, pulp, and the edible part of pepper on silica gel with ethyl acetate – dichloromethane – formic acid – acetic acid – water 100:25:10:10:11. Detection by spraying with Natural Product reagent and anisaldehyde sulfuric acid solution. Qualitative identification under UV 254 and 366 nm.

J. Planar Chromatogr. 31, 163-168 (2018). HPTLC bioautography of the essential oil in the bark of Ocotea quixos on silica gel with toluene – ethyl acetate – petroleum ether 97:7:20. After separation, the Mueller‒Hinton culture medium was deposited on the Petri dish which contained the chromatographic plate. The medium contained the selected microorganisms: 500 μL Bacillus subtilis ATCC 6633 ATCC and 500 μL P. aeruginosa ATCC 9027. The plate was incubated at 37 °C for 48 h. The molecule with activity proved to be cinnamyl acetate at an hRF value of 53.

Rapid Commun. Mass Spectrom. 32, 2113-2121 (2019). HPTLC of dihexadecylphosphatidylethanolamine, dihexadecylphosphatidylglycerol, dihexadecylphosphatidylcholine, monohexadecylphosphatidylethanolamine and tetratetradecenylcardiolipid in the lipidome of P. aeruginosa on silica gel with chloroform – methanol – acetic acid – water 170:45:20:8. Detection by exposure to iodine vapor. Phospholipid identification by mass spectrometry.

Rapid Commun. Mass Spectrom. 33, 185-192 (2019). HPTLC of phospolipids (1) and neutral lipids (2) in the extensor digitorum longus, soleus and gastro muscle on silica gel with methyl acetate – 1‐propanol – chloroform – methanol – 0.25 % aqueous potassium chloride 25:25:25:10:9 for (1) and n‐hexane – diethyl ether – acetic acid 80:30:1 for (2). Detection by spraying with primuline reagent. Qualitative identification under UV light. TLC‐matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry imaging was performed to verify the compositions of molecular species.

J. Chromatogr. 315, 101-109 (1984). TLC of naturally occurring flavone aglycones on silica with benzene - methanol - acetic acid 45:3:2 or with chloroform - hexane - methanol 40:40:3. AIso TLC of permethylated flavones on silica with chloroform - ethyl acetate - acetone 5:4:1, butanol-hexane 15:85 or benzeneethyl acetate 6:4. Detection by UV 366 nm. The 5-hydroxy-flavones with methoxy groups at 6 or 8 showed dark purple colors. Rf values of 16 5-hydroxy-flavones. In general, 6-methoxyflavones showed higher Rf values than the corresponding 8-methoxy compounds.