Heliyon 6(8), e04654 (2020). HPTLC of ethanolic extracts of three algae (100µg/band) on silica gel, along with carotenoid standards (10µg/band), developed with toluene – acetone 7:3. Detection under white light. Carotenoids appeared orange or yellow, chlorophylls green, pheophytins dark khaki. Carotenoid patterns of the algae were very different depending on the family: red alga Eucheuma denticulatum (Solieriaceae) contained mainly zeaxanthin and lutein (hRF 44) and β-carotene (hRF 88), but also β-cryptoxanthin (hRF 69-71) and fucoxanthin (hRF 39); brown alga Sargassum polycystum (Sargassaceae) contained mainly fucoxanthin, and also cryptoxanthin; green alga Caulerpa lentillifera (Caulerpaceae) contained mainly zeaxanthin, but also astaxanthin (hRF 61) and canthaxanthin (hRF 77) in smaller amounts. Separately, HPLC-MS was used to confirm and quantify these compounds, which was necessary for carotenoids with similar hRF values: zeaxanthin and lutein (hRF 44), and β-carotene and lycopene (hRF 88).

J. Planar Chromatogr. 33, 647-661 (2020). HPTLC of empaglifozin (1) and linagliptin (2) on silica gel with chloroform - methanol - ammonia (25 %) 100:10:1. Quantitative determination by absorbance measurement at 225 nm. The hRF values for (1) and (2) were 31 and 71, respectively. Linearity was between 100 and 5000 ng/zone for (1) and 50 and 2500 ng/zone for (2), respectively. Intermediate precision was below 2 % (n=3). The LOD and LOQ were 32 and 97 ng/zone for (1) and 14 and 42 ng/zone for (2), respectively. Average recovery was 100.1 % for (1) and 99.9 % for (2). Comparison with a similar TLC method showed no significant statistical differences.

J. Planar Chromatogr. 33, 631-646 (2020). HPTLC of azilsartan medoxomil (1) and chlorthalidone (2) on silica gel with toluene - methanol - ethyl acetate - formic acid 35:10:5:1. Quantitative determination by absorbance measurement at 241 nm. The hRF values for (1) and (2) were 55 and 36. Linearity was between 800 and 4000 ng/zone for (1) and 250 and 1250 ng/zone for (2), respectively. Intermediate precision was below 2 % (n=3). The LOD and LOQ were 15 and 44 ng/zone for (1) and 10 and 32 ng/zone for (2). Recovery was between 100.8 and 101.7 % for (1) and 99.4 and 101.0 % for (2).

J. Planar Chromatogr. 33, 231-244 (2020). HPTLC of apremilast on silica gel with toluene - methanol - ethyl acetate 7:2:1. Quantitative determination by absorbance measurement at 241 nm. The hRF value for apremilast was 63. Linearity was between 200 and 1000 ng/zone. Inter-day and intra-day precision were below 1 % (n=3). The LOD and LOQ were 4 and 13 ng, respectively. Recovery rate was between 99.7 and 100.0 %. Apremilast was subjected to acidic, alkaline, oxidative, dry heat, neutral, and photolytic degradation conditions. The method was implemented using a quality risk management and quality by design approach for regulatory requirements.

XLVI. Synthesis of 2-substituted-5,6-pentamethylene-5,6-hexamethylene-and 5,6- decamethylenepyrimidine-4 (3H)- ones. Acta Chimica 115, 231-235 (1984). TLC of 2-substituted-5,6- pentamethylene-5,6- hexamethylene and 5,6-decamethylenepyrimidine-4- (3H)- ones on silica with benzene - ethanol 4:1. Detection with iodine vapours.

J. Chromatogr. 607, 91-95 (1992). Investigation of the relationship between GLC retention properties and Rf values in TLC with molecular connectivity indices for a series of benzodiazepines. Employed were multiple correlation coefficients, standard errors of estimate, F-Snedecor function values and Student’s-test as the criteria for best equation selection. The effect of the polarity of the mobile phases in TLC was also investigated.

J. Planar Chromatogr. 1, 214-219 (1988). Ion-pair TLC on octadecyl-bonded silica with buffered mobile phase containing N-cetyl-N,N,N,-trimethylammonium bromide as ion- pair reagent. Detection under UV 366 nm. Quantification by fluorodensitometry at 404 nm. Detection limit, 10 fmol. The calibration curves of all 6 substances were linear between 0.15 and 3 pmol. r = 0.999. The repeatability of the results from one plate to another was good.

J. Planar Chromatogr. 15, 383-386 (2002). TLC of 7 meso-tetraphenylporphyrin derivatives on silica gel, alumina, cellulose, polyamide and on RP-phase with Cu(II) and chiral reagent with 26 different mobile phases. Detection by visual inspection.