Food Chem. 341, 128271 (2021). HPTLC of finger millet (Eleusine coracana L.) on silica gel with n-butanol - water - acetic acid 4:1:1. Detection by spraying with ninhydrin, followed by heating at 100 °C. Amino acid profiling under UV light at 546 nm. The hRF values for 21 standard amino acids ranged from 2 to 51.

Food Chem. 338, 128115 (2020). 2D HPTLC of tangeretin (1), 5-demethyltangeretin (2), nobiletin (3), 3′-demethylnobiletin (4), 4′-demethylnobiletin (5), 3′,4′-didemethylnobiletin (6), 5-demethylnobiletin (7), 5,3′-didemethylnobiletin (8), 5,4′-didemethylnobiletin (9), 5,3′,4′-tridemethylnobiletin (10), naringenin (11), hesperetin (12), naringin (13) and hesperidin (14) on silica gel with dichloromethane - methanol 20:1 containing 1 % acetic acid in the first direction, then the plate was rotated 90° to the right and eluted with petroleum ether - acetone 3:2. The hRF values for (1) to (12) were 53, 62, 46, 36, 38, 18, 57, 48, 51, 27, 43 and 42, respectively. Detection under UV light at 254 and 366 nm and by spraying with 1 % vanillin in ethanol with several drops of concentrated sulfuric acid; or with 3 % iron chloride dissolved in 0.5 M hydrochloric acid solution for compounds with a phenolic hydroxyl group. The LOD for (1) to (14) under 254 nm ranged from 0.5 to 2.5 mM, while 0.1 to 2.5 mM under 366 nm. Quantitative determination by surface-enhanced raman spectroscopy (SERS).

Food Chem. 357, 129135 (2021). HPTLC of cinnamon on silica gel with toluene - ethyl acetate - methanol 6:5:3. Nine detection modes were used: 1) white light illumination, 2) UV 366 nm, 3) UV 254 nm, and six different derivatization reagents applied by immersion: 4) primuline reagent (100 mg primuline, 20 mL water and 80 mL acetone), 5) p-anisaldehyde sulfuric acid reagent (1 mL methoxy benzaldehyde, 140 mL methanol, 16 mL acetic acid and 8 mL sulfuric acid), 6) vanillin sulfuric acid reagent (1 g vanillin, 80 mL ethanol and 0.8 mL sulfuric acid), 7) diphenylamine aniline o-phosphoric reagent (2 % each of diphenylamine and aniline in 100 mL isopropanol plus 20 mL o-phosphoric acid), 8) Fast Blue B salt reagent (100 mg Fast Blue B salt in 100 mL ethanol, 70 %) and 9) natural product reagent (1 g 2-aminoethyl diphenyl borate in 100 mL ethanol), followed by heating at 110 °C (5), 120 °C (4, 6) or 140 °C (7, 8) for 3-5 min. Effect-directed profiling was performed through eight different assays: HPTLC–Aliivibrio fischeri bioassay, HPTLC–Bacillus subtilis bioassay, HPTLC–tyrosinase inhibition assay and densitometric evaluation, HPTLC–α–glucosidase and β–glucosidase inhibition assays, HPTLC–AChE and BChE inhibition assays, HPTLC–DPPH assay. Compounds were further characterized by heated electrospray ionization high–resolution mass spectrometry (HESI–HRMS).

Food Chem. 343, 128400 (2020). HPTLC fingerprint of Citrus bergamia fruits from the islands of Kefalonia, Corfu and R. Calabria on silica gel with chloroform - methanol - water 13:9:3. Qualitative identification under UV light at 280 nm.

Food Chem. 362, 130132 (2021). HPTLC of betanin (1) and vulgaxanthin I (2) in beetroot (Beta vulgaris L. subsp. vulgaris) on RP-18 silica gel with water - acetonitrile -  trifluoroacetic acid 40:10:1. Quantitative determination by absorbance measurement at 535 nm for (1) and 484 nm for (2). The hRF values for (1) and (2) were 38 and 58, respectively.

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1932521 (2021). HPTLC of gallic acid in the stem bark of Schinus terebinthifolius on silica gel with toluene - ethyl acetate - formic acid - methanol 15:15:4:1. The plates were scanned at 254 nm and 366 nm. The hRF value for gallic acid was 43. Image features were acquired using a combination of two approaches: Haralick texture features and Zernike moments. The GNU OctaveVR software was used to set the architectures of the Artificial Neural Network. The mathematical data provided by the image analysis was correlated with the gallic acid content determined by HPLC. The method allowed the prediction of phenolic content through TLC plate images.

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1930556 (2021). HPTLC of patulin in apple juice on silica gel with methyl tert-butylether - n-pentane 9:5. Detection by spraying with 0.25 % methyl-benzothiazolinone hydrazone hydrochloride monohydrate in methanol, followed by heating at 105 °C. Quantification was performed using a 48-bit flatbed scanner for color measurements (in red, green, and blue). Quantification in fluorescence mode by use of a 16-bit CCD-camera and UV-366 nm illumination as well as a HPTLC DAD-scanner. The hRF value for patulin was 58. Linearity was between 5 and 800 ng/zone. The LOD and LOQ were 33 and 67 ng/zone, respectively.

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1930555 (2021). HPTLC of ofloxacin (1), tinidazole (2), terbinafine hydrochloride (3), and clobetasol propionate (4) on silica gel with toluene - ethyl acetate - methanol - triethylamine - formic acid 50:40:10:3:3. Quantitative determination by absorbance measurement at 238 nm. Linearity was between 300 and 1500 ng/zone for (1) to (4). The intermediate precision was below 2 % (n=6). Recovery was between 98.9 and 99.1 % for (1), 98.9 and 99.3 % for (2), 99.0 and 99.5 % for (3) and 98.9 and 99.3 % for (4).