J. Planar Chromatogr. 32, 41-46 (2019). HPTLC of ayapanin in the leaves of Ayapana triplinervis on silica gel with ether - ethyl acetate 3:2. Quantitative determination by absorbance measurement at 254 nm. The hRF value of ayapanin was 56. Linearity was between 200 and 1000 ng/zone. The intermediate precision was below 0.8 % (n=6). The LOD and LOQ for ayapanin were 54 and 169 ng/zone, respectively. Recovery rate was 99.7 % for ayapanin.

) wood enzyme extract with catechins. J. Planar Chromatogr. 21, 83-88 (2008). TLC of (+)-catechin and (-)-epicatechin on silica gel with diisopropyl ether - formic acid 91 in an unsaturated twin-trough chamber. Detection by spraying with vanillin-sulfuric acid reagent followed by heating at 120 °C for 5 min. Quantitative determination by absorbance measurement at 490 nm.

CBS 107, 13-15 (2011). HPTLC of 5-hydroxymethylfurfural (HMF) in honey on silica gel, prewashed with methanol - water 61, with ethyl acetate. Quantitative determination by densitometry in absorbance mode at 290 nm. Optional detection by immersion in p-aminobenzoic acid reagent followed by heating at 110 °C for 5-10 min. The hRf value of HMF was 80. The calibration function was polynomial in the range of 0.8-80 ng/band whilst Michaelis Menten 2 regression was suitable for higher concentrations. The LOD of HMF in honey samples was 0.75 mg/kg (12 µL applied) and the LOQ 2.4 mg/kg. The method complies with the requirement of max. 15 mg/kg of HMF in honey. The results with this method were compared with those obtained by the spectrophotometric Winkler method and by HPLC-UV and mean differences were minor (3.3 % or 0.9 mg/kg). Complementary confirmation by HPTLC-MS online coupling. HMF zones identified under UV were eluted and analyzed by ESI-MS in full-scan and SIM mode.

by principal component analysis. J. Planar Chromatogr. 28, 274-279 (2015). DPPH-HPTLC bioautography assay of Hibiscus sabdariffa on silica gel with toluene - ethyl acetate - formic acid - methanol 303085. Analysis by dipping into 0.05 % DPPH methanolic solution. Combination with liquid chromatography-quadrupole time-of-flight mass spectrometry enabled the rapid screening and identification of the antioxidants in Hibiscus sabdariffa.

Planta Medica 83(03/04), 326-333 (2017). Usnic acid, precipitated by low temperature (4 °C) from a benzene Soxhlet extract of the lichen Usnea amblyoclada, was purified by preparative layer chromatography on silica gel with chloroform – n-hexane 41. Detection at UV 254 nm. Yield was 1.1 % of the dried plant.

J. Ethnopharmacol. 233, 141-147 (2019). HPTLC of gentiopicrin in the dried roots and rhizomes of Gentiana scabra on silica gel with ethyl acetate – ethanol – water 821. Detection by spraying with chromogenic reagent (acetic acid – sulfuric acid – p-anisaldehyde 10021). Qualitative evaluation at UV 254 nm. The hRF value for gentiopicrin was 58.

(Coumarin drugs - quality testing of the umcka drug and its preparations.) Dtsch. Apoth. Ztg. 128, 292-296 (1988). TLC of umckalin, scopoletin umckalinic acid, umckalin-7-O-glucoside on silica with ethyl acetate - formic acid - acetic acid - water 100111126. Detection under UV 365 nm after spraying with KOH solution; separation of umckalin and scopoletin with toluene - ether 5050 saturated with 10% aqueous acetic acid.

Helv. Chim. Acta 72, 1455-1462 (1989). TLC of plant extracts containing chromonocoumarins on silica with chloroform - methanol 955 or chloroform - methanol - water 65355 and HPTLC on RP-8 with methanol - water 73 or 82. Detection under UV 266 nm. Bioautography on silica with the plant pathogenic fungus Cladosporium cucumerinum. Also HPLC and low pressure liquid chromatography.