J. of Chromatogr. Sci. 58 (1), 16 - 21 (2020). Development of a selective and sensitive method for the simultaneous determination of a new combination of quinfamide and mebendazole in bulk powder and in pharmaceutical formulation by HPTLC on silica gel with methanol - toluene 1:3. Quantitative determination by densitometry at 254 nm. Validation of the method according to ICH guidelines. Successful application for determination of quinfamide and mebendazole in tablets. Statistical comparison between the developed HPTLC method and a reported simultaneous equation spectrophotometric method showed no significant difference, proving the suitability for quality control testing of the studied drugs.

J. of Chromatogr. Sci. 57 (9), 799 - 805 (2019). Description of a method for the quantification of R, R-glycopyrronium bromide (GLY) and its related impurities in drug substance and drug product by HPTLC on silica gel with dichloromethane - methanol - formic acid 20:1:1. GLY and its related impurities (glycopyrronium impurity G and glycopyrronium impurity J) were separated with hRf values of 17, 34 and 69, respectively. Quantitative determination at 220 nm in the range of 0.3 - 10 and 0.2 - 4.0 μg/zone. The LOD and LOQ were 0.1, 0.3 and 0.05, 0.2 μg/zone for GLY and its related impurities, respectively. The recovery was 99.5 ± 1.4, 100.0 ± 1.3 and 99.6 ± 0.8 and R2 ≥ 0.9968 for GLY and its impurities, consecutively.

J. Liq. Chromatogr. Relat. Technol. 43, 925-933 (2020). HPTLC of 21 cycloalkylspiro-5-hydantoins on RP-18 with mixtures of water and organic solvent (acetone: 0.5-0.8 v/v, 1,4-dioxane: 0.5-0.74 v/v, tetrahydrofuran: 0.4-0.7 v/v, acetonitrile: 0.5-0.7 v/v). Detection at UV 254 nm. The logarithm of partition coefficient, log P, for the investigated compounds was calculated. Multivariate data analysis (hierarchical cluster analysis (HCA) and principal component analysis (PCA) was performed.

J. Liq. Chromatogr. Relat. Technol. 43, 852-862 (2020). HPTLC of diphenylacetamide derivatives on RP-18 with binary mixtures of organic modifier (ethanol, n-propanol, tetrahydrofuran and acetonitrile 36–52 % with 4 % increments). Detection at UV 254 nm. Lipophilicity of examined derivatives was determined. Two multivariate methods, Cluster Analysis, (CA) and Principal Component Analysis, (PCA) were performed to study the compliance of the chromatographic parameters, the standard measure of lipophilicity, the pharmacokinetic predictors and the toxicity parameters of the substances.

J. Liq. Chromatogr. Relat. Technol. 43, 580-588 (2020). Retardation factor (hRF) of 42 amino acids in two different eluents (acetonitrile - sodium azide and 1,2 dioxane-sodium azide solutions) were predicted by different quantitative structure-retention relationship (QSRR) methods. The method analyzed the effect of sum of geometrical distances between N and O in separation of amino acids in RP-TLC.

J. Planar Chromatogr. 33, 281-291 (2020). HPTLC of Weikangling capsules (a Chinese patent medicine for treating chronic gastritis, containing Paeoniae Radix Alba, Glycyrrhizae Radix et Rhizoma, Bletillae Rhizoma, Notoginseng Radix et Rhizoma, Poria, Corydalis Rhizoma, Sepiae Endoconcha, and Belladonnae Extractum) on silica gel with chloroform - methanol - water 14:5:1. Detection by spraying with 10 % sulfuric acid in alcohol, followed by heating at 105 ºC for 5 min. Qualitative analysis at UV 366 nm.

J. Planar Chromatogr. 33, 429-437 (2020). Review of the application of TLC and HPTLC for the analysis of vitamins covering the period of 2011-2019. The authors describe stationary and mobile phases for the TLC/HPTLC analysis of water and fat-soluble vitamins. The review highlightes that none of the papers reviewed showed the use of surfactants or ionic materials as impregnating agents or mobile phase modifers.

J. Planar Chromatogr. 33, 523-530 (2020). HPTLC of clonazepam (1), lorazepam (2), alprazolam (3), diazepam (4), furazepam (5), oxazepam (6) and nitrazepam (7) in urine on silica gel with chloroform - glacial acetic acid 9:1. Direct extraction of the substances from the plate into a mass spectrometer. The hRF values for (1) to (7) were 73, 44, 22, 64, 18, 53 and 40, respectively. Linearity was between 0.2 and 0.8 µg/mL. Intermediate precision was below 5 %. LOD was 1 ng/mL for each substance. Average recovery was 67.1 % for (1), 68.9 % for (2), 64.2 % for (3), 73.1 % for (4), 50.7 % for (5), 81.4 % for (6) and 64.4 % for (7).