J. Planar Chromatogr. 33, 263-269 (2020). HPTLC of the interaction between methylene blue and purified glutathione-S-transferase (5 mmol/L methylene blue and enzyme solution in 0.1 mol/L potassium phosphate buffer) on silica gel with butanol - acetic acid - water 12:3:5 for 2 h. Detection by spraying with ninhydrin (0.25 % in acetone). The complex that most likely came from the interaction of methylene blue and purified glutathione-S-transferase had a hRf of 16.

J. Liq. Chromatogr. Relat. Technol. 43, 233-246 (2020). HPTLC of lutein (1) and lactucaxanthin (2) in three varieties of lettuce (Iceberg, Romania, and green lettuce) on silica gel with heptane - acetone 7:3. The hRF values for (1) and (2) were 44 and 41, respectively.

J. Liq. Chromatogr. Relat. Technol. 43, 445-454 (2020). HPTLC of aniline (1), 2,4-xylidine (2) and 4-aminoazobenzene (3) in chili oils, pickles and related food matrices on silica gel with chloroform - acetic acid 9:1. Quantitative determination by absorbance measurement at 280 nm. The hR_F values for (1) to (3) were 53, 43 and 82, respectively. Linearity was in the range of 2-14 ppm for (1) to (3). The LOD and LOQ were 0.0015 and 0.0045 ppm for (1), 400 and 1200 ppm for (2) and 200 and 600 ppm for (3), respectively. Mean recovery rate was 100.2 % for (1) and 100.9 % for (2). The azo aryl amines were also analyzed using a TLC-MS interface.

J. Planar Chromatogr. 33, 11-18 (2020). HPTLC of lutein in dietary supplements on silica gel with n-heptane – ethyl acetate 9:1. The part of the TLC chromatogram containing the zone visible in day light was cut off, followed by developing in the opposite direction with n-heptane – acetone – ethyl acetate 11:5:4. Quantitative determination by absorbance measurement at 450 nm. Linearity was between 90 and 500 ng/zone for lutein. Intermediate precisions were below 2 % (n=9). The LOD and LOQ were 50 and 90 ng/zone, respectively. Recovery rate was between 87 and 102 %.

J. Planar Chromatogr. 32, 59-60 (2019). TLC of p-phenylenediamine on silica gel with ethyl acetate - diethyl ether 1:1. Detection by spraying with aqueous alkaline solution of Folin’s reagent (0.5 % Folin’s reagent in 5 % sodium carbonate solution). The hRF value of p-phenylenediamine was 45. The LOD for p-phenylenediamine was approximately 3 μg by visual evaluation.

J. of Chromatogr. A 1257, 195-203 (2012). Based on the recent description of the fabrication of TLC plates from patterned carbon nanotube (CNT) forests via direct infiltration/coating of the CNTs by low pressure chemical vapor deposition of silicon from SiH4, followed by high temperature oxidation of the CNTs and Si, an improved microfabrication process for the preparation of these TLC plates has been presented. First, deposition of a few nanometers of carbon and/or a thin film of Al2O3 on the CNTs, confirmation of the presence of additional oxygen after carbon deposition by X-ray photoelectron spectroscopy, after priming, coating of the plates by rapid, conformal deposition of an inorganic material that does not require subsequent oxidation, i.e., by a fast pseudo atomic layer deposition (?-ALD) of SiO2 from trimethylaluminum and tris(tert-butoxy)silanol and faithful reproduction of the features in the masks is still observed after oxidation. Fast, highly efficient separations of the fluorescent dyes eosin Y disodium and sulforhodamine B were achieved on amino phase with LiCl - methanol 1:100 over 30 mm migration distance.

J. Planar Chromatogr. 4, 365-369 (1991). TLC and HPTLC separation of 8 thiazin dyes (thionine, azure A, azure B, azure C, methylene blue, new methylene blue, toluidine blue, methylene violet) on silica with 1-butanol - acetic acid - water in different ratios. Optimum solvent for all dyes except methylene violet 1-butanol - formic acid - water 10:1:1. Quantification by densitometry.

J. Liq. Chromatogr. & Rel. Technol. 26, 819-832 (2003). TLC of carotenoid colorings (annatto extract, orange color, gardenia yellow, paprika color, tomato color, marigold color, b-carotene) on RP-18 with acetonitrile - acetone - n-hexane 11:7:2 and acetone - water 9:1 and on silica gel with n-hexane - ether - acetic acid 4:1:1 and benzene - ethyl acetate - methanol 15:4:1. Color standards were i.a. capsanthin, b-carotene, b-cryptoxanthin, bixin, crocetin, lycopene, lutein, crocin, and norbixin.