J. Agric. Food Chem. 69, 12686-12694 (2021). HPTLC of 2Z,8Z- and 2E,8Z-matricaria esters in European goldenrod (Solidago virgaurea) and E- and Z-dehydromatricaria esters in grass-leaved goldenrod (Solidago graminifolia) and showy goldenrod (Solidago speciosa) on silica gel with n-hexane − acetone 17:3. Detection by dipping into mycelium suspension of F. avenaceum and B. sorokiniana, followed by incubation in a vapor chamber at 21 °C for 48−72 h. The lack of visible white (F. avenaceum) or dark gray (B. sorokiniana) fungal mycelia indicated the inhibition zones on the bioautograms. Compounds were further analyzed by high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy.

J Chromatogr A, 1641, 462334 (2021). Validation of a newly built (using 3D-printing) and newly configurated on-surface multi-purpose autosampler, called “autoTLC−LC−MS system”, developed for orthogonal hyphenation of normal phase HPTLC with reversed phase HPLC and high-resolution MS. Details and protocols are given for the construction, installation and numerical control software programming of this autosampler. HPTLC of antibiotics cefoperazone (third-generation cephalosporin), clindamycin (lincosamide), erythromycin A (macrolide), ipronidazole (nitro-imidazole), nafcillin (penam), sulfaquinoxaline (sulphonamide), tiamulin (pleuromutilin), and trimethoprim (DHFR inhibitor) on silica gel without development. Bioassay with Bacillus subtilis: bacterial suspension was sprayed onto the plate, which was  horizontally incubated for 2 h at 37°C in a humid box; afterwards, the plate was sprayed with 0.2% MTT solution, incubated again for 30 min at 37°C, dried for 10 min at 50°C, and documented under white light. The image was uploaded as a template in the updated TLC–MS managing software, so that by clicking on the zones of the image showing antibacterial activity, the corresponding zones of the untreated plate, placed on a newly designed plate holder, were sequentially eluted by the round elution head of the automatic sampler into the RP-18 endcapped HPLC monolithic column connected to a Quadrupole-Orbitrap mass spectrometer. For the elution from the plate and HPLC separation, a gradient was used (flow rate 0.2 - 0.5 mL/min, depending on the step), with different proportions of two mobile phases: A) 0.1 % formic acid and 4 mM ammonium formate in water; B) 0.1 % formic acid and 4 mM ammonium formate in methanol. After separation in the column, antibiotics directly underwent electrospray ionization in positive mode (voltage 3.5 kV, capillary temperature 320 °C, probe heater temperature 350 °C) and were detected by HRMS. For validation, the achieved ranges were 2.1–14.1 % for intra-day and 2.5–16.1 % for inter-day precisions.

J. Planar Chromatogr. 34, 203-209 (2021). HPTLC of triclosan in toothpaste on silica gel with n-heptane - methyl tert-butyl ether - acetic acid 920:80:1. Detection by spraying with 2,6-dichloroquinone-4-chloroimide in 50 mL methanol, followed by spraying with an aqueous sodium carbonate solution (1 g/10 mL). Plates were scanned using a flatbed scanner. The hRF value for triclosan was 22. Linearity was between 100 and 1000 ng/zone. The LOD and LOQ were 46 and 91 ng/zone, respectively. Average recovery was 93.2 %.

J. Planar Chromatogr. 34, 253-261 (2021). HPTLC of emtricitabine (1) and tenofovir alafenamide fumarate (2) on silica gel with ethyl acetate - n-hexane - methanol - ammonia solution 20:20:10:1. Quantitative determination by absorbance measurement at 260 nm. Linearity was between 400 and 2000 ng/zone for (1) and 50 and 250 ng/zone for (2). Intermediate precisions were below 2 % (n=3). The LOD and LOQ were 29 and 87 ng/zone, respectively. Recovery was between 100 and 102 % for (1) and 100 and 103 % for (2).

J. Planar Chromatogr. 34, 271-278 (2021). HPTLC of tedizolid phosphate on silica gel with chloroform - methanol 9:1. Quantitative determination by absorbance measurement at 300 nm. The hRF value for tedizolid phosphate was 46. Linearity was between 10 and 2000 ng/zone. Intermediate precisions were below 2 % (n=6). The LOD and LOQ were 3 and 10 ng/zone. Recovery was between 98.5 and 101.7 %.

J. Planar Chromatogr. 34, 189-195 (2021). HPTLC of tacrolimus on silica gel with acetonitrile - ethyl acetate - glacial acetic acid 60:20:20:1. Detection by spraying with anisaldehyde reagent (0.5 mL of p-anisaldehyde was mixed with 10 mL of glacial acetic acid, 85 mL of methanol and 5 mL of sulfuric acid), followed by heating at 100 °C for 3 min. Quantitative determination by absorbance measurement at 366 nm. The hRF value for tacrolimus was 20. Linearity was between 20 and 140 ng/zone. Intermediate precisions were below 3 % (n=3). The LOD and LOQ were 6 and 17 ng/zone, respectively. Mean recovery was 101.6 %.

Sens. Actuators. B. Chem. 325, 128753 (2020). Leucomalachite green (1) and malachite green (2) and certain amount of highly dispersed potassium iodate titanium dioxide composites (0.1 M titanium butoxide was used as a precursor with 5 % potassium iodate solution to prepare KIO3-doped TiO2 nanoparticles). The sample was developed with chloroform - methanol 4:5. Detection by dipping into 5 % potassium iodine, followed by heating and then dipping into a zinc ion solution followed by heating at 80 °C. Linearity was in the range of 0.3–8.0 μg/mL for (1) and 0.1–4.0 μg/mL for (2), respectively. LOD and LOQ were 1.7 and 5.2 μg/kg for (1) and 0.9 and 2.7 μg/kg for (2), respectively.

Food Chem. 351, 129211 (2021). High-throughput planar solid-phase extraction of 66 multi-class antibiotic residues in muscle tissue, cow milk and chicken eggs on silica gel with acetonitrile - methanol - ammonia 5:3:2 as first front-elution up to 85 mm followed by a second front-elution in the reverse direction up to 25 mm with acetonitrile -water - ammonia 9:7:4. Evaluation under UV 254 nm and 366 nm. Detection of macrolides by spraying with p-anisaldehyde sulfuric acid reagent (methanol - glacial acetic acid - sulfuric acid - p–anisaldehyde 420:50:26:3), followed by heating at 110°C for 3 min. Detection of penicillins by spraying with ninhydrin reagent (500 mg ninhydrin in ethanol - glacial acetic acid 23:2). Detection of lincosamines by spraying with aniline diphenylamine o-phosphoric acid reagent (2 g diphenylamine in methanol – o-phosphoric acid - aniline 90:10:1). Via simple clicks on the image, the auto TLC-MS interface automatically eluted the target zones at the trace level from the TLC plate into a Q Exactive Plus Hybrid Quadrupole-Orbitrap Mass Spectrometer.