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, 1640, 461929 (2021). Study of the impact of different strains, culture media and parameters (temperature, time, rotational speed, and glucide and amino-acid supply) on the metabolite profile of bacteria. Samples were cultivation broths of Bacillus subtilis, B. licheniformis, B. pumilus and B. amyloliquefaciens, as well as their respective supernatant liquid-liquid extracts (apolar solvents only or QuEChERS method with acetonitrile and MgSO4 – NaCl mixture 4:1). HPTLC on silica gel (normal phase and RP-18), either as bands (for small volumes of extracts) or as areas for supernatants and bigger volumes of extracts. Extract areas were focused with a three-step procedure (up to 20mm with acetone, and twice with methanol); unextracted supernatants were focused twice with methanol and once with tetrahydrofuran, but the application zone of the plate had to be cut before development, due to the high matrix load. Development with ethyl acetate – methanol – water at different ratios after activation of the plate surface with magnesium chloride (33% relative humidity), evaluation in white light and UV. Detection of antibacterial compounds with Aliivibrio fischeri bioassay. Derivatization with primuline (for lipophilic substances) and diphenylamine aniline sulfuric acid reagent (for saccharides). This method allowed a fast comparison: A) of the patterns of the different strains (presence /absence and intensity of detected or antibacterial bands); B) of cultivation parameters: the number of metabolites increased with time, rotational speed (oxygen level), and at 37°C (vs. 30°C), whereas a minimal medium allowed the detection of more metabolites, due to the lower matrix load; C) of the impact of the extraction parameters: choice of the solvents (QuEChERS method had no advantage here), solvent – supernatant ratio (1:3 showed richer patterns than 1:1); D) of the HPTLC parameters used (better separation and resolution with normal phase vs. RP18 layers).

J. Liq. Chromatogr. Relat. Technol. https://doi.org/10.1080/10826076.2021.1933025 (2021). Laser fabrication of open capillary microchannels on cyclic olefin polymer susbtrates as stationary phase. Microchannels of 24 µm X 68 µm depth were produced using a neodymium-doped yttrium aluminum garnetan laser (Nd:YAG). The ultra thin layer chromatography layer was used for the separation of Fast Green for food coloring (1) and rhodamine 6G (2) and compared with a comercial RP-TLC. The hRF values for (1) and (2) were 9 and 18 using the UTLC plate and 10 and 57 with the RP-TLC plate. The paper highlighted the potential to tailor the surface chemistry through known surface functionalization routes for cyclic olefin polymer susbtrates that will allow unique applications for the UTLC plate.

J. of Chromatogr. A 1218 (37), 6540-6547 (2011). New approach and application of highly automated planar chromatographic tools for powerful clean-up, called high-throughput planar solid phase extraction (HTpSPE), which is indispensable for preventing matrix effects in multi-residue analysis of pesticides in food by liquid and gas chromatography coupled to mass spectrometry, employing TLC to completely separate pesticides from matrix compounds and to focus them into a sharp zone, followed by extraction of the target zone by the TLC-MS interface, thus resulting in extracts nearly free of interference and free of matrix effects, as shown for seven chemically representative pesticides in four different matrices (apples, cucumbers, red grapes, tomatoes), and completion of clean-up of one sample in a manner of minutes. Regarding the clean-up step, quantification by LC–MS with mean recovery (against solvent standards) of 90–104% and relative standard deviations of 0.3–4.1% (n = 5) for two spiking levels of 0.1 and 0.5 mg/kg.

Chromatographia 27, 617-621 (1989). Evaluation of the florisil clean-up procedure for its suitability of quantifying aflatoxin in sorghum grain by bi-directional HPTLC. Investigation of the accuracy and precision of the method. Detec tion limits, 0.13˜0.36 µg/kg. Comparison with the AOAC CB method.

CBS 107, 9-10 (2011). Extraction of pesticides from fruit and vegetable samples by QuEChERs method. TLC of acetamiprid, azoxystrobin, chlorpyriofos, fenarimol, mepanipyrim, penconazole and pirimicarb on amino phase aluminum foil (prewashed with acetonitrile) with acetonitrile over a migration distance of 75 mm in the first direction. After drying development in the backwards direction over 45 mm with acetone. Evaluation under UV 254 nm, UV 366 nm, white light and under UV 366 nm after immersion in primuline solution. Extraction of the target zone by TLC-MS interface with acetonitrile - 10 mM ammonium formate 1:1. Average recoveries of the seven pesticides were 90-104 % with %RSD of 0.3-4.1 % (n = 5). This new high-throughput planar solid phase extraction method for multi-residue analysis of pesticides in food allows a rapid and efficient clean-up at low costs and low solvent consumption.

Chromatographia 29, 177-181 (1990). Evaluation of a modified phenyl non-polar bonded-phase clean-up procedure for bi-directional HPTLC. Separation of aflatoxins in aqueous acetone extracts of maize on silica. Evaluation of the accuracy and precision of the method for a range of aflatoxin concentrations between 3.4 and 901 µg/kg, CV = 1.7-10.8%, with mean recoveries of 92-99%. Discussion of the systematic errors and the detection limits. Comparison of the method with CB and Romer ones.

Clean-up of matrix-rich samples using high-troughput planar solid phase extraction (HTpSPE). Black and green tea samples were spiked with 7 pesticides (acetamiprid, azoxystrobin, chlorpyrifos, fenarimol, mepanipyrim, penconazole, and primicarb) at level 0.01, 0.1 and 1 mg/kg. Extraction with acetonitrile, pre-cleaning by dispersive SPE. TLC on silica gel (prewashed with acetonitrile) of samples applied as rectangles of 3 x 16 mm first with acetonitrile - water 19:1 over 85 mm and after drying for 5 min with acetone - water 7:1 in the opposite direction over 31 mm. Detection under UV 254 and 366 nm and by dipping in primuline reagent (0.2 % in acetone - water 4:1) and detection under UV 366 nm and white light. Elution of target zones into autosampler vials by TLC-MS Interface with acetonitrile - 10 mM ammonium formate buffer 1:1, flow rate 0.2 mL/min. After clean-up the samples are free of caffeine which interferes with pesticide detection.