J Chromatogr A, 1619, 460945 (2020). Samples were lamotrigin as standard, or extracted with an oil-in-water microemulsion (10 µL butyl acetate, 4 mL n-butanol, 925 mg sodium dodecyl sulphate, 8.6 mL water) either from patients’ raw plasma (for separation from blood proteins) after spiking, or from commercial tablets dissolved in methanol. TLC on silica gel with a water-in-oil microemulsion of 9 mL butyl acetate, 1 mL n-butanol, 250 mg sodium dodecyl sulphate, 250 µL water. Both optimal microemulsions were predicted using Taguchi orthogonal array and Plackett-Burman design. Evaluation in UV 254 nm, quantification from the digital picture using four image processing software programs. For lamotrigin (hRF 24), limits of quantification were 170 ng for pure drug and 10 ng for spiked plasma. Linearity (in range 20–200 ng/spot) was directly obtained for the calibration curve in spiked plasma; however, for pure drug, linearity was obtained only when using log values of the calculated densities (300–3000 ng/spot).

J Chromatogr A, 1598, 196-208 (2019). Samples were acertone – water 7:3 extracts of Reynoutria japonica (= Fallopia japonica = Polygonum cuspidatum) rhizomes (Polygonaceae) as well as flavanols (catechin, epicatechin, epicatechin gallate, epigallocatechin gallate) and procyanidins (A1, A2, B1–B3 and C1) as standards. HPTLC on diol silica gel with: (MP1) acetonitrile; (MP2) ethyl acetate; (MP3) ethyl acetate – formic acid 90:1; or (MP4) toluene – acetone – formic acid 3:6:1. Prewashing of the plates with mobile phase was needed only with MP1. After drying under hot air stream, derivatization by automated immersion into DMACA (dimethylaminocinnamaldehyde) – HCl solution (60 mg in 13 mL HCl + 187 mL ethanol), followed by 2 min drying under warm air stream. Visualization under UV 366 nm and white light, densitometry in absorption/reflectance mode at 280 nm (before derivatization) or 655 nm (10 min after derivatization). Bands of interest were eluted from layer with acetonitrile – methanol 2:1 through the oval elution head of a TLC-MS interface pump, into a RP18 liquid chromatography guard column, followed by a quadrupole ion trap mass spectrometer. Full scan mass spectra (m/z 150–2000) were recorded in negative mode using electrospray ionization (spray voltage 4 kV, capillary temperature 200◦C, capillary voltage -38.8 V). Monomer gallates to hexamer gallates were detected, separated with MP1, MP2 or MP4; monomers and oligomers (not gallates) were separated with MP3 (up to hexamers) and with MP1 and MP4 (up to decamers). Moreover, enhanced absorption of standards was also studied for influence of mobile phases, of layers (diol silica gel vs. classical silica gel vs. cellulose) and of luminosity (light vs. dark).

J Chromatogr A, 1684, 463582 (2022). Samples were concentrated filtrates of leachates of waste deposition sites, as well as testosterone, flutamide, bisphenol A (BPA) and nitroquinoline oxide (NQO) as standards. Automated Multiple Development on HPTLC silica gel (prewashed with methanol and dried 30 min at 110 °C) with 1) methanol up to 20 mm; 2A) chloroform – ethyl acetate –petroleum ether 11:4:5 or 2B) ethyl acetate – n-hexane 1:1 for flutamide and testosterone, up to 90 mm. Effect-directed analysis was performed by automated spraying 3 mL suspension of BJ1991 yeast (transfected Saccharomyces cerevisiae strain, pure for androgenic activity, with 50 ng/mL testosterone for anti-androgenic assay), followed by 20 h incubation at 30 °C in a closed chamber (90 % relative humidity), by 5 min drying under cold air stream, by spraying 2.5 mL MUG solution (4-methylumbelliferyl-galactopyranoside) and by 15 min incubation at 37 °C in an open chamber. Agonistic and antagonistic activities were detected qualitatively under UV 366 nm (light or dark blue bands, respectively, on blue background) and quantitatively documented using automated scanning at excitation wavelength 320 nm (deuterium lamp), with cut-off filter at 400 nm. Dose-response curves for model compounds were established by regression analysis. Anti-androgenic effective doses at 10 % were 28 ng/zone for flutamide and 20 ng/zone for BPA, without toxicity for the yeast. To exclude cytotoxicity where anti-androgenic activity was observed, the HPTLC layers (either without or after the spraying with MUG) were sprayed with 3 mL resazurin solution (0.01 % in water) and incubated 30 min at 30 °C and 90 % humidity. Cytotoxicity bands appeared as pink zones of resorufin on a colorless background (dihydroresorufin) under white light. Densitometric evaluation in absorption mode at 575 nm (under deuterium and halogen-tungsten lamps, no filter applied). NQO was cytotoxic at its lowest tested dose (1 ng/zone).

J. Planar Chromatogr. 35, 439-451 (2022). HPTLC of withanoside IV (1), withanoside V (2), withaferin A (3), and kaempferol-based glucoside (4) in the roots and aerial parts of Withania somnifera on silica gel with ethyl acetate - chloroform - methanol - water 40:15:22:9. Detection of (1) to (3) by spraying with anisaldehyde sulfuric acid reagent, followed by heating at 100 °C for 3 min. Quantitative determination by absorbance measurement at 540 nm for (1) to (3) and 254 nm for (4). The hRF values for (1) to (4) were 33, 42, 62 and 21, respectively. Linearity was between 200 and 1000 ng/zone for (3) and (4) and 400 and 2000 ng/zone for (1) and (2). Interday and intra-day precisions were below 4 % (n=6). The LOD and LOQ were 180 and 544 ng/zone for (1), 215 and 652 ng/zone for (2), 170 and 516 ng/zone for (3) and 48 and 144 ng/zone for (4). Recovery was between 95.9 and 99.6 % for (1) and (4).

J. Planar Chromatogr. 35, 509-517 (2022). HPTLC of tamsulosin hydrochloride (1) and tolterodine tartrate (2) binary mixture on silica gel with ethyl acetate - n-hexane - diethylamine 9:3:1. Quantitative determination by absorbance measurement at 225 nm. The hRF values for (1) and (2) were 40 and 85, respectively. Linearity was between 10 and 200 ng/zone for (1) and 100 and 900 ng/zone for (2). The LOD and LOQ were 3 and 8 ng/zone for (1) and 22 and 66 ng/zone for (2), respectively. Average recovery was 100.1 % for (1) and 100.7 5 for (2).

J. Planar Chromatogr. 35, 519-532 (2022). HPTLC of binary mixtures of the novel oral anticoagulants (NOACs) apixaban (1), edoxaban tosylate (2) and rivaroxaban (3) with the lipid-lowering statin, rosuvastatin calcium (4) on silica gel with toluene - ethyl acetate - methanol - 25 % ammonia 35:45:20:2 (method 1) for the three mixtures, and methanol - 25 % ammonia 199:1 (method 2) for (2)/(3) mixture only. Quantitative determination by absorbance measurement at 291 nm. The hRF values for (1) to (4) were 65, 20, 75 and 10 using method 1, and 40 for (2) and 90 for (4) using method 2. Linearity was between 5 and 45 µg/mL for (1) to (4). Interday and intra-day precisions were below 3 % (n=6). The LOD and LOQ were 0.1 and 0.4 µg/mL for (1), 1 and 4 µg/mL for (2) and (3), 0.4 and 1 µg/mL for (4) using method 1, and 1.4 and 4.7 µg/mL for (2) and 0.4 and 1.2 µg/mL for (4) using method 2. Average recovery was between 97.6 and 102.9 % for (1) to (4).

J. Planar Chromatogr. 35, 473-479 (2022). HPTLC of capsaicin and dihydrocapsaicin as capsaicinoids in Habanero pepper pods on silica gel with cyclohexane - chloroform - acetic acid 7:2:1. Quantitative determination by absorbance measurement at 254 nm. The hRF value for capsaicinoids was 29. Linearity was between 0.5 and 4.0 µg/zone. Interday and intra-day precisions were below 6 % (n=6). The LOD and LOQ were 251 and 750 ng/zone, respectively. 

J. Planar Chromatogr. 35, 491-500 (2022). HPTLC of gallic acid in fern species Drynaria
quercifolia, Diplazium esculentum, and Asplenium nidus on silica gel with ethyl acetate - formic acid - acetic acid - water 120:11:11:26. Detection by heating at 100 °C for 3 min, followed by dipping into NP reagent (1.0 g of 2-aminoethyl diphenyl borate in 200 mL of ethyl acetate and stored at 4 °C). Quantitative determination by absorbance measurement at 366 nm. The hRF value for gallic acid was 82. Interday and intra-day precisions were below 1 % (n=3).