PLoS ONE 18(11), e0294054 (2023). Sample was a pigment extracted with methanol from cell pellets of Serratia marcescens strain BRL41 (Yersiniaceae). TLC on silica gel with ethyl acetate. Detection under daylight. The pink pigment had the same hRF value (87) and colour as prodigiosin from standard strain ATCC-13880.

Food Chem. 421, doi.org/10.1016/j.foodchem.2023.136217 (2023). HPTLC of scopoletin in cassava landraces on silica gel with ethyl acetate - dichloromethane - acetic acid - formic acid - water 23:6:2:2:2. Detection under UV light at 366 nm.

 J. Pharmacogn. Phytochem. 12(1), 6-14 (2023). TLC silica gel layers were used to monitor the purification through column chromatography (CC) of a chloroform fraction of the methanolic root bark extract of Rauvolfia vomitoria (Apocynaceae). Mobile phases were petroleum ether – ethyl acetate 4:1 (MP1), dichloromethane – methanol 20:1 (MP2), and dichloromethane – methanol 15:1 (MP3). Visualization under UV 254 nm. Preparative TLC on thicker silica gel was performed on two subfractions: (A) with dichloromethane – methanol 100:7 for the isolation of the methyl esters of eudesmic acid and of trimethoxycinnamic acid (hRF values 35 and 28, respectively, in MP1); (B) with MP2 for the isolation of an indole alkaloid: kumujan B (= 1-carbomethoxy-β-carboline, hRF value 40 in MP2). Other indole alkaloids were isolated through CC: ajmaline, mauensine and reserpine (hRF values 35, 13 and 47, respectively, in MP3).

J. Planar Chromatogr. 36, 71-76 (2023). HPTLC of melamine (1), formaldehyde (2) and genotoxins (3) in bamboo tableware on silica gel with iso-propanol - ethyl acetate - water 10:5:6 for (1), chloroform - dichloromethane - diethyl ether 4:5:6 for (2) and (3). Genotoxin analysis by spraying with Salmonella suspension followed by spraying FDG substrate solution and incubation at 37 °C for 15 min. Qualitative analysis at 254 nm and densitometric absorption measurement at 202 nm for (1) to (3).

Marine Drugs 20(4), 270 (2022). Samples were ether glycerols (EG) purified: (A) from Chimaera monstrosa liver oil (Chimaeridae); (B) from mixed liver oil of sharks Centrophorus squamosus (Centrophoridae) and Somniosus microcephalus (Somniosidae); (C) from Macaca fascicularis hearts (Cercopithecidae); (D) from tumors obtained by grafting in mice the human melanoma cell line MDA-MB-435s, and (E) from periprostatic adipose tissue of men with prostate cancer. Reduction of (phospho)ester glycerolipids into EG and fatty alcohols was part of the purification process. Octadecyl-glycerol and octadecenyl-glycerol were used as standards of alkyl- and alkenyl-glycerols, respectively. HPTLC on silica gel previously developed with chloroform – methanol 1:1, air-dried and activated for 30 min at 110° C. Application under nitrogen stream (6 bar). Development with petroleum ether – diethyl ether – acetic acid 60:140:1. After 2 h drying at room temperature under ventilation hood, visualization by 50 s immersing into sulfuric acid (7 % in ethanol), followed by 2 h drying under air-stream, and 14 min heating at 140° C. Plates were documented under white light illumination and densitometry was performed by computered scanning of the pictures. Alkyl-glycerols (mean hRF 34, LOQ 1235 ng/band) and alkenyl-glycerols (mean hRF 44, LOQ 2352 ng/band), present in all samples (except alkenyl-glycerols in shark oil), were quantified after method validation for specificity, sensitivity, accuracy, precision and repeatability. Linearity range was 1000 ng – 7000 ng for both EG types. To confirm the band identification, samples and standards were also submitted to acidic hydrolysis before HPTLC application. In this case, the bands of alkenyl glycerols did not appear, because chlorhydric acid reacted with the vinyl ether bonds to form glycerol and aldehydes.

Heliyon 7(2), e06116 (2021). Samples were a methanolic extract of a semi-solid ayurvedic conserve (ashwagandhadi lehyam) prepared with Withania somnifera roots (Solanaceae) and five other plants, as well as standards: withaferin A and withanolide A (= withaniol), two ergostane triterpene steroids with lactone cycle and epoxide. HPTLC on silica gel with toluene – ethyl acetate – formic acid 6:4:1. Visualization and densitometric scanning at UV 254 nm and 366 nm (deuterium lamps). Derivatization by immersion into vanillin – sulfuric acid reagent, followed by oven heating at 105 °C until optimal coloration. Documentation under white light and densitometry scanning at 540 nm (tungsten lamp). Both analytes (hRF 35 and 45 respectively) were shown at 254 nm and 540 nm (but not at 366 nm), in the standards and in the extract.

Food Chem. 133263 (2022). HPTLC of 27 hand-filtered coffee brews of differently roasted coffee beans and 14 differently prepared and stored coffee brews on amino phase with a 3-step gradient: 1) methanol - ethyl acetate 13:7 (1), 2) ethyl acetate - toluene - formic acid - water 70:11:15:4, and stopped below the eluted alkaloids caffeine and theobromine; and 3) up to 13 mm with water - methanol 3:2. The hRF values for caffeine, theobromine, theophylline and 5-O-caffeoylquinic acid  were 95, 85, 18 and 21 in step (1), while for ferulic acid, coumaric acid, caffeic acid, nicotinic acid and gallic acid were 60, 54, 51, 35 and 10 during step (2), and for melanoids was 12 in step (3). The following effect-directed assays on the chromatogram were also performed: DPPH scavenging asay, Aliivibrio fischeri bioassay, Bacillus subtilis bioassay, acetylcholinesterase inhibition assay, α-glucosidase inhibition assay and planar yeast estrogen screen (pYES) bioassay. Further analysis by mass spectrometry using a electrospray interface. Coffee brews made by a fully automated coffee machine showed the highest antioxidative potential.

J Chromatogr A, 1603, 355–360 (2019). Samples were ethyl acetate root macerates of fully flowered Tanacetum vulgare (Asteraceae). HPTLC on silica gel (classical irregular particles vs. Lichrosphere with spherical particles) previously washed with methanol, dried for 5 min at room temperature, perimeter-sealed with a polymer coat, and heated for 30 min at 100 °C. Separation with toluene or with toluene – n-hexane 7:3, in classical capillary flow or in OPLC (overpressured layer chromatography). For OPLC, off-line infusion was used (closed mobile phase (MP) outlet, automatically stopping development); external pressure 50 bar, rapid MP flush 175 and 350 µL, MP flow rate 250 and 500 µL/min, 1830 and 3475 µL MP, development time 446 s and 424 s. Derivatization by immersion into vanillin – sulfuric acid reagent, followed by 5 min heating at 110 °C; or into PABA reagent (500 mg p-aminobenzoic acid, 18 mL glacial acetic acid diluted, 20 mL water, 1 mL o-phosphoric acid, 60 mL acetone), followed by 5 min heating at 140 °C. Effect-directed analysis using automated immersion: A) for free radical (DPPH•) scavengers; B) for activity against Gram-negative bacteria using Aliivibrio fischeri bioluminescence assay; C) for activity against Gram-positive bacteria with Bacillus subtilis bioassay. Four active polyynes were identified as hexadiynylidene-epoxy-dioxaspiro-decane (1), pontica epoxyde (nonene-triynyl-vinyl-oxirane) (2), tetradeca-triine-en-one (3) and trans-(hexadiynylidene)-dioxaspiro-decene (4), by hyphenating OPLC to quadrupole-orbitrap HRMS without eluent, using a DART interface (Direct Analysis in Real-Time, needle voltage 4kV, grid voltage 50 V, helium as gas, temperature 500 °C, full scan in positive ionization mode in m/z range 100-750). Polyynes (3) and (4) were coeluting in HPTLC but not in OPLC, demonstrating that (4) is not produced by oxidation during the DART-MS procedure. Separation with OPLC compared to HPTLC was performed in a shorter time and with better resolution at the same time. Layers with spherical particles gave higher resolution; zone distortions occurring in OPLC due to dissolved air in MP were prevented by previous MP sonication.