J. of Chromatogr. Sci. 58 (5), 427 - 432 (2020). HPTLC of ulipristal acetate (UPA) in presence of its degradation products on silica gel with ethyl acetate - toluene - glacial acetic acid 40:70:3. UPA was subjected to acid and alkali hydrolysis, oxidation, photo and thermal degradation. The hRF of UPA was 38. Quantitative determination by densitometry. The linearity range was between 400-3600 ng/band. LOD was 72 ng/band and LOQ 220 ng/band. The recovery was 100.1-100.7 %. The method is accurate, precise, robust, and specific to measure UPA in presence of degradants.

Biochem. Biophys. Res. Commun. 525, 61-66 (2020). HPTLC of complete precursors of glycosylphosphatidylinositol (GPI) in Gpi8 deficient strains of Candida albicans on silica gel with chloroform - methanol - water 4:4:1. Metabolic labeling was performed using [2-3H]-myo-inositol. Detection of radiolabeled glycolipid intermediates by scanning for 5 min.

J. Sep. Sci. 43, 2981-2988 (2020). HPTLC of citicoline (1) and piracetam (2) in presence of their degradation products on silica gel with methanol - chloroform - ammonium chloride buffer 9:1:2. Quantitative determination by absorbance measurement at 230 nm. The hRF values for (1) and (2) were 15 and 85, respectively. Linearity was between 0.2 and 4 µg/zone for both (1) and (2). Intermediate precision was below 2 % (n=3). The LOD and LOQ were 56 and 180 ng/zone for (1) and 53 and 170 ng/zone for (2), respectively. Average recovery was 100.9 % for (1) and 99.8 % for (2).

J. of Chromatogr. Sci. 58 (5), 418 - 426 (2020). Development of a method for the quantitation of glibenclamide (GLIBEN), rosiglitazone maleate (ROSI) and metformin hydrochloride (MET) from a combined dosage form by HPTLC on RP-18 F254s aluminum layer with methanol - tetrahydrofuran - water - glacial acetic acid 40:9:10:1. Detection under UV light. The hRf for GLIBEN, ROSI and MET was 54, 62 and 80, respectively. Quantification and photodocumentation by densitometry. For GLIBEN and  ROSI the LOD and LOQ was 80 and 200 ng/zone, for MET the LOD and LOQ was 48 and 120 ng/zone, respectively. The linearity for GLIBEN and ROSI was 200 - 1000 ng/zone (r = 0.9991 for GLIBEN and r = 0.9993 for ROSI) and for MET 120 - 600 ng/zone (r = 0.9988). The method was precise and accurate for all three drugs, and well suitable for the analysis of triglucored tablets, and reliable quality control for GLIBEN, ROSI and MET in a combined dosage form.

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. of Chromatogr. Sci. 57 (6), 552-559 (2019). Analysis of chlorpheniramine maleate (CM), phenylephrine (PE) and guaifenesin (GF) in their mixture and in presence of the GF related substance guaiacol (GL) and the cough syrup preservative sodium benzoate (NaB) by TLC on silica gel with ethyl acetate - methanol - toluene - ammonia 14:3:2:1. Quantitative determination by absorbance measurement at 270 nm. The method was suitable for the determination of CM, PE, and GF in pure powder and in combined cough syrup without interference from the excipients.

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).

J. Planar Chromatogr. 33, 481-487 (2020). HPTLC of resveratrol in the fruits of Morus alba on silica gel with hexane - ethyl acetate - glacial acetic acid 40:60:1. Quantitative determination by absorbance measurement at 302 nm. The hRF value for resveratrol was 56. Linearity was between 100 and 1600 ng/zone. Intermediate precision was below 2 % (n=6). The LOD and LOQ were 16 and 46 ng/zone, respectively. Recovery was between 90.3 and 96.5 %.