J. Liq. Chromatogr. Relat. Technol. 35, 1676-1685 (2012). HPTLC of ranitidine hydrochloride thermal decomposition products on silica gel with dimethyl sulfoxide (DMSO), acetonitrile, methanol, 25 % ammonia, 2-propanol, and 2-methoxyethanol in a concentration range of 0-100 %. Detection under UV light at 254 nm. Degradation products with the binary mobile phases are arranged in three groups, depending on the retention: acetonitrile/DMSO at 373K (product 3), acetonitrile/DMSO at 353 K (product 3), and 2-methoxyethanol/DMSO at 353 K and 373 K (product of 2 and 3).

CBS 107, 2-4 (2011). HPTLC of chloroform extracts from cleaning swabs on silica gel with toluene - ethyl acetate 3:2 after 10 min chamber saturation. Densitometric evaluation for identification of substances by spectra recording at 200-350 nm, quantification with 3-level calibration. Detection by immersion in methanol - sufuric acid 9:1 and heating at 105 °C for 5 min. Cleaning validation by HPTLC (i.e. determination of residues of hormonal ingredients) can be achieved with the required accuracy. The method is simple and quick and the quantitative results are precise.

J. Planar Chromatogr. 26, 325-330 (2013). HPTLC of piperine (1) and gallic acid (2) in pharmaceuticals on silica gel with toluene - ethyl acetate 3:7. Quantitative determination by absorbance measurement at 340 nm for (1) and 254 nm for (2). The hRf values of (1) and (2) were 55 and 19, respectively. Linearity was between 250 and 1250 ng/zone for (1) and 750 and 1750 ng/zone for (2). LOD and LOQ were 10 and 33 ng/zone for (1) and 25 and 83 ng/zone for (2). Recovery (by standard addition) was in the range of 94-103 %. Intermediate intra- and inter-day precision was below 0.7 % (n=3).

J. Planar Chromatogr. 28, 74-82 (2015). HPTLC of two binary mixtures containing (1) omeprazole with (2) ketoprofen (mixture A) and (3) esomeprazole with (4) naproxen (mixture B) on silica gel with chlorofom - ethylacetate 3:7. Quantitative determination by absorbance measurement at 302 nm. The hRF values of (1) to (4) were 21, 49, 22 and 65, respectively. Linearities were between 30 and 300 ng/zone for (1) and (3), between 200 and 2000 ng/zone for (2) and between 500 and 6000 ng/zone for (4). The intermediate intra-day and inter-day precisions were below 2 % (n=3). The LOD and LOQ were 10 and 30 ng/zone for (1) and (3), 30 and 100 ng/zone for (2) and 150 and 500 ng/zone for (4), respectively. Recoveries for (1) to (4) ranged between 98 and 102 %.

J. Planar Chromatogr. 29, 287-298 (2016). HPTLC of 34 structurally diverse drugs on RP-18 with acetonitrile – pH 7.4 phosphate buffered saline 7:3. Detection under UV 254 nm. Molecular descriptors were investigated to assign the compounds to two clusters: central nervous system active (CNS+) or inactive (CNS-) describing the ability of the compounds to penetrate the brain.

J. Planar Chromatogr. 29, 380-387 (2016). HPTLC of metolazone (1) and spironolactone (2) on silica gel with ethyl acetate ‒ chloroform ‒ glacial acetic acid 50:50:1. Quantitative determination by absorbance measurement at 238 nm. The hRF values for (1) and (2) were 51 and 79, respectively. Linearities were between 50 and 300 ng/zone for (1) and 200 and 1200 ng/zone for (2). The intermediate precisions were below 1.3 % (n=6). The LODs and LOQs were 2 and 5 ng/zone for (1) and 5 and 16 ng/zone for (2). Average recoveries were 99.7 % for (1) and 99.7 % for (2). The developed method successfully separated drug substances from degradation products formed under various stress conditions.

J. Planar Chromatogr. 30, 350-356 (2017). HPTLC for the enantioresolution of atenolol, betaxolol, and orciprenaline racemic mixtures using the chiral selector (S)-Glu as an additive of the stationary phase (A) or the mobile phase (B). For method (A), the chiral selector (50 mL of 0.5 % (S)-Glu) was mixed with a slurry of silica gel (25 g) and the plate was developed with acetonitrile – methanol – dichloromethane – water 10:3:3:2. For method (B), the mobile phase was acetonitrile – methanol – water 7:1:1 admixed with 0.5 % (S)-Glu. Detection by exposure to iodine vapor. LOD for each enantiomer was in the range of 1.4-1.9 μg/zone. Recovery was between 96.2-99.1 % for_x000D_
both (S)- and (R)-atenolol.

J. Planar Chromatogr. 31, 469-476 (2018). HPTLC of metformin hydrochloride (1) and dapagliflozin (2) on silica gel with acetonitrile ‒ ammonium acetate 10% ‒ acetic acid 90:9:1. Quantitative determination by absorbance measurement at 228 nm. Linearity ranged between 1-10 μg/mL for (1) and 10-100 μg/mL for (2). LOD and LOQ were 314 and 950 ng/mL for (1) and 3.1 and 9.4 μg/mL for (2). The intermediate precision was <2 % (n=3). Average recovery was 99.9 % for (1) and 99.6 % for (2).