Braz. J. Pharm. Sci. 58, e18691 (2022). HPTLC of paracetamol (1), diclofenac sodium (2), ibuprofen (3), and indomethacin (4) in wastewater effluents on silica gel with n-hexane - ethyl acetate - acetic acid 12:7:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (4) were 18, 56, 69 and 44, respectively. Linearity was between 0.1 and 0.9 µg/zone for (1) to (4). Inter-day and intra-day precisions were below 1 % (n=3). Mean recovery was 99.7 % for (1), 99.8 % for (2), 99.7 % for (3) and 99.2 % for (4). 

Trends Anal. Chem. 159, 116915 (2023). Review of analytical methodologies, distribution, ecotoxicity and removal of artificial sweeteners to determine the ecological and health risks that these substances may pose based on available data. The paper described analytical techniques, including HPTLC for the determination of artificial sweeteners in water samples.

Trends Anal. Chem. 154, 116654 (2022). Review of recent advances of sampling and sample preparation in effect-directed environmental analysis with a special focus on innovative approaches. The paper summarized sampling, enrichment and fractionation techniques for effect-directed analysis of water samples, including HPTLC methods for the analysis of potential toxicity contributors.

J Chromatogr A, 1624, 461239 (2020). Samples were chemical standards of acetylcholinesterase (AChE) inhibitors (azamethiphos, caffeine, donepezil, galanthamine, methiocarb-sulfoxide, paraoxon-ethyl) and of neurotoxic compounds, as well as drinking or contaminated water samples enriched through solid phase extraction. HPTLC on spherical silica gel (pre-washed twice by 20 min immersion in isopropanol, heated 20 min at 120 °C before and after pre-washing with acetonitrile). First separation (preparative TLC) with automated multiple development (16 steps). Effect-directed analysis for AChE inhibitors by immersion (speed 5 cm/s, time 1 s) into enzyme solution, incubation 5 min at 37 °C and immersion into substrate solution (indoxyl acetate 2 % in methanol); visualization under UV 366 nm. Active zones from untreated layers were eluted through the oval head of a TLC-MS interface to a second plate for a second separation with a panel of other mobile phases. Bands of interest were eluted from the second layer with water through the oval elution head of the TLC-MS interface pump, into a RP18 liquid chromatography guard column, followed by a quadrupole time-of-flight mass spectrometer. Full scan mass spectra (m/z 100–1200) were recorded in negative and positive modes using electrospray ionization (and collision-induced dissociation for MS2). Among the water contaminants, lumichrome (riboflavin photolysis product), paraxanthine and linear alkylbenzene sulfonates were identified as AChE inhibitors.

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. 32, 421-429 (2019). HPTLC of levamisole (1), pyrantel pamoate (2), albendazole (3), and febantel (4) on silica gel with dichloromethane - methanol - formic acid 18:1:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (4) were 10, 15, 47 and 79, respectively. Linearity was between 600 and 1500 µg/L for (1), 400 and 1000 µg/L for (2), 200 and 1000 µg/L for (3) and (4). The obtained RSD values were in the range from 7.0 % to 8.8 % for intra-day precision and from 8.1 % to 13.1 % for inter-day precision (n=3). The LOD and LOQ were 300 and 600 µg/L for (1), 200 and 400 µg/L for (2) and 100 and 200 µg/L for (3) and (4), respectively. Recovery rate was above 95 % for (1) to (4).

J. Planar Chromatogr. 32, 173-182 (2019). HPTLC of chlorinated metformin samples with genotoxic effect obtained by umu assay (Salmonella typhimurium TA1535/pSK1002 Assay) on silica gel in a gradient development with methanol - formic acid 2000:1, dichloromethane and n-hexane. A TLC-MS interface was used for further analysis by LC-high-resolution mass spectrometry. 

J. Sep. Sci. 31, 71-77 (2008). HPTLC of acrylamide in drinking water on silica gel, derivatization in situ with 5-dimethylamino-naphtalene-1-sulfinic acid (1.6 µg/µL in methanol), followed by heating at 120 °C for 1 hour and developed with ethyl acetate. For fluorescence enhacement, the plate was dipped into a solution of 25 % polypropylene glycol in n-hexane and dried immediately. Quantitative determination by fluorescence at 366/>400 nm. Verification was based on HPTLC-ESI/MS, HPTLC-direct analysis in real time (DART)-TOF/MS and NMR. The hRf value of acrylamide (as 3-dansylpropanamide) was 69. Linearity was between 0.1 and 0.4 µg/L. Within-run precision and the mean between-run precision (n=3) were 4.6 and 11.0 %. The limit of detection and quantification for acrylamide was 0.025 and 0.083 µg/L, respectively. Recovery (by standard addition) was 96.4 %. The method showed comparable result with HPLC-MS/MS.