by TLC-MS-coupling. CBS 109, 5-7 (2012). HPTLC of Rheum root extracts on silica gel (pre-washed with isopropanol, activated for 30 min at 120 °C) with toluene - ethyl acetate - formic acid 5:4:1 for fraction (1), 4:5:1 for fractions (2) to (6), 3:6:1 for fraction (7), 3:7:1 for fraction (8) and 2:7:1 for fractions (9) and (10). Detection under white light and UV 366 nm after dipping in 1 % ethanolic vanillin solution for 3 s, drying, heating at 63 °C for 5 min and exposure to 37 % HCl vapors. Elution of target zones by TLC-MS Interface, flow rate 0.1 mL/min, for ESI MS in negative mode.

Food Chem. 187, 460-468 (2015). HPTLC-direct bioautography of bioactive compounds in the extracts of cold-pressed hemp (1), flax (2) and canola (3) seed oil on silica gel with toluene - ethyl acetate - formic acid - water 15:30:5:3 for (2) and toluene - ethyl acetate - acetic acid 80:25:4 for (1) and (3). HPTLC-DPPH scavenging activity was determined by dipping into a methanolic DPPH solution, followed by drying for 90 s in the dark and heating at 60 °C for 30 s. The hRF values of dominant radical scavenging zones were in the range of 75-85 for (1), 70-90 for (2) and 64 and 95-100 or (3). HPTLC-antimicrobial Aliivibrio fischeri assay allowed the determination of major antimicrobial zones at hRF 40-49 and 55-66 or (1), 23, 45 and 60 for (3) and 95 for (2). Additional effect-directed analyses employing acetylcholinesterase (AChE) assay, planar yeast estrogen (pYES) bioassay and Bacillus subtilis bioassay as well as subsequent HPTLC-ESI-MS allowed targeted characterization of bioactive compounds.

J. Planar Chromatogr. 29, 127-131 (2016). Over-pressured layer chromatography of gallic acid in the fruits of Annona muricata on RP-18 with an isocratic solvent system consisting of 0.1 % acetic acid in water (A) and methanol (B) at a flow rate of 0.15 mL/min and the eluent pressure below 40 bar. Quantitative determination by absorbance measurement at 270 nm. Linearities were between 0.1 and 0.5 mg/mL. The intermediate precisions were below 0.6 % (n=3). The LOD and LOQ were 522 and 1581 mg/mL. Recoveries ranged between 99 and 103 %.

J. Chromatogr. A 1465, 197-204 (2016). Demonstration of a strategy for an improved quality control of propolis shown on the example of 30 French propolis samples based on evaluation of their HPTLC fingerprints in combination with selected mass signals obtained by desorption-based scanning mass spectrometry (MS). Separation of the French propolis sample extracts by HPTLC on silica gel with n-hexane – ethyl acetate - acetic acid 5:3:1 and on RP phase with n-hexane – toluene – ethyl acetate – formic acid – acetic acid 16:6:10:3:3, both in twin-trough chambers with 37 % hydrochloric acid applied on a filter paper in the second trough of the chamber. Analysis of the fingerprints, obtained by two different detection modes, i.e. after (1) derivatization with NP and PEG reagents and fluorescence detection at UV 366 nm and (2) scanning direct analysis in real time (DART)-MS, by multivariate data analysis. The best classification was obtained using both methods, RP-HPTLC-FLD and RP-HPTLC-DART-MS, in combination with pattern recognition techniques, such as principal component analysis. Observation of the characteristic patterns from the two types, in which all investigated French propolis samples were divided. Identification of phenolic compounds, such as caffeic acid, p-coumaric acid, chrysin, pinobanksin, pinobanksin-3-acetate, galangin, kaempferol, tectochrysin and pinocembrin, as characteristic marker compounds of French propolis samples. Confirmation of the presence of two botanically different types of propolis, known as the blue and orange types.

Food Chem. 243, 258-268 (2018). HPTLC of [6]-gingerol (1) and [6]-shogaol (2) in 17 ginger rhizomes and ginger-containing food products on silica gel with n-hexane – ethyl acetate 13:7. Detection by dipping into anisaldehyde sulfuric acid reagent (5 mL concentrated sulfuric acid was added to a mixture of 500 μL anisaldehyde, 10 mL acetic acid and 100 mL methanol), followed by heating at 110 °C for 5 min. Quantitative determination by absorbance measurement at 580 nm. The hRF values for (1) and (2) were 32 and 41, respectively. LOD and LOQ were 25 and 45 ng/zone for (1) and 20 and 40 ng/zone for (2), respectively. The primuline reagent (100 mg primuline in 200 mL acetone – water 4:1) was also investigated for detection, but it was not as sensitive. Polynomial calibrations ranged between 0.9982 and 0.9999. Their contents ranged 0.2–7.4 mg/g (1) and 0.2–3.0 mg/g (2) in the different products. Intermediate precisions were mostly ≤8 % for (1) and ≤10 % for (2) in the different food matrices. Effect-directed detection was performed via A. fischeri and B. subtilis bioassays, tyrosinase and AChE inhibition assays and DPPH* radical scavenging assay. Active unknown zones were further characterized by HPTLC-ESI-HRMS and assigned as [8]-gingerol and [10]-gingerol. Among others, further multi-detected zones were assigned to be [4]-gingerol, dehydro-[6]-gingerdione, dehydro-[6]-gingerol, dehydro-[8]-gingerol, dehydro-[10]-gingerol etc.

Planta Medica 83(14/15), 1149-1158 (2017). The cyclodextrane fractionation of the methanolic percolate of Salix reticulata aerial parts was analyzed on silica gel with ethyl acetate – methanol – water 100:13:10. Detection by derivatization with vanillin-sulfuric acid reagent. Luteolin and apigenin glycosides, catechin, procyanidins and phenolic glucosides (picein, triandrin, and salicortin) were isolated from these fractions through preparative HPLC._x000D_

TLC separation of xanthohumol, humulone and lupulone on silica with cyclohexane - ethyl acetate - propionic acid. Examination by UV 254 and 366 nm and spraying with vanillin - sulfuric acid reagent. Chromatographic separation to be carried out protected from light. New semi quantitative TLC analysis.

(TLC separation and identification of phenolic components in desinfectants as coupling products with fast blue salt BB.) Z. Anal. Chem. 332-372 (1988). TLC separation of methyl and dimethyl phenols after coupling with Fast Blue Salt BB on silica potassium carbonate 1:2 with dichloromethane - ethyl acetate - diethylamine 92:5:3.