J. Planar Chromatogr. 34, 55-60 (2021). TLC of genistein‑7‑O‑[α‑rhamnopyranosyl‑(1 → 6)]‑β‑glucopyranoside (GTG) in Derris scandens on silica gel with ethyl acetate - methanol - water 80:13:10. Quantitative determination by absorbance measurement at 254 nm for (1), 256 nm for (2), 300 nm for (3) and 296 nm for (4). The hRF value for GTG was 26. Linearity was between 8 and 120 µg/mL. Intermediate precision was below 2 % (n=3). The LOD and LOQ were 3 and 9 µg/mL. Recovery was between 102.3 and 108.6 %. The results obtained from the TLC–densitometric, TLC–image analysis and HPLC methods were comparable.

J. Planar Chromatogr. 34, 39-44 (2021). HPTLC of salicylic acid (1), kaempferol (2), gallic acid (3), and protocatechuic acid (4) in Cinnamomum verum on silica gel with toluene - ethyl acetate - formic acid 5:4:1. Quantitative determination by absorbance measurement at 302 nm for (1), 256 nm for (2), 300 nm for (3) and 296 nm for (4). The hRF values for (1) to (4) were 54, 66, 31 and 37, respectively. Linearity was between 200 and 700 ng/zone for (1) and 100 and 600 ng/zone for (2) to (4). Intermediate precision was below 2 % (n=3). The LOD and LOQ were 70 and 200 ng/zone for (1), 40 and 100 ng/zone for (2) to (4). Recovery was between 97.8 and 98.9 % for (1), 98.1 and 99.0 % for (2), 97.4 and 99.2 % for (3) and 98.4 and 99.5 % for (4).

J. Planar Chromatogr. 34, 31-38 (2021). HPTLC of reserpine (1), scopoletine (2), piperine (3), bacoside A (4) and lupeol (5) in a polyherbal formulation (containing Rauwolfia serpentina, Nardostachys jatamansi, Convolvulus pluricaulis, Bacopa monnieri, Piper longum) on silica gel with benzene - ethyl acetate - glacial acetic acid - n-butanol 57:30:10:3 for (1), (2) and (3), n-butanol - glacial acetic acid - water 18:3:4 for (4) and benzene - ethyl acetate 9:1 for (5). Detection by spraying with 5 % methanolic sulfuric acid solution, followed by heating at 80 °C for 20 min. Quantitative determination by absorbance measurement at 254 nm for (1) to (3), 598 nm for (4) and 580 nm for (5). The hRF values for (1) to (5) were 17, 53, 73, 34 and 48, respectively. Linearity was between 1 and 2 µg/zone for (1), 2.5 and 4.5 µg/zone for (2), 10 and 50 µg/zone for (3), 12 and 24 µg/zone for (4) and 1 and 5 µg/zone for (5). Intermediate precision was below 2 % (n=6). The LOD and LOQ were 6 and 20 ng/zone for (1), 13 and 38 ng/zone for (2), 11 and 33 ng/zone for (3), 377 and 1143 ng/zone for (4) and 324 and 982 ng/zone for (5), respectively. Average recovery was 98.1 %for (1), 99.9 % for (2), 99.9 for (3), 99.7 % for (4) and 99.5 % for (5).

J. of Chromatogr. Sci. 59 (7), 634-641 (2021). TLC of ledipasvir on silica gel with ethylacetate – hexane – acetonitrile – trimethylamine 12:7:3:1. Detection by exposure to strong UV irradiation to enhance the fluorescence properties of ledipasvir and densitometric scanning at 315 nm⁠. The hRF of ledipasvir was 28 and of sofosbuvir 36. Linearity was in the range of 5-50 ng/band⁠. The method is suitable for the specific determination of ledipasvir in pharmaceutical tablets without interference from sofosbuvir or excipients, thus for the estimation of ledipasvir in fecal specimens with adequate recovery and for testing the content uniformity of ledipasvir in the pharmaceutical tablets.

J. Planar Chromatogr. 33, 609-616 (2020). HPTLC of oleuropein in the leaves of Olea europaea on silica gel with ethyl acetate - methanol - water 16:2:1 (method 1) and on RP-18 phase with ethanol - water 11:9 (method 2). Quantitative determination by absorbance measurement at 200 nm. The hRF values for oleuropein were 47 and 78 for methods (1) and (2), respectively. Linearity was between 200 and 1400 ng/zone for both methods, respectively. Intermediate precision was below 2 % (n=6). The LOD and LOQ were 68 and 203 ng/zone for method (1) and 69 and 206 ng/zone for method (2). Recovery was between 99.7 and 98.2 % for method (1) and 99.7 and 99.3 % for method (2).

J. Planar Chromatogr. 33, 663-667 (2020). HPTLC of sotalol on silica gel using (S)-levofloxacin as chiral selector, with acetonitrile - methanol - water 13:5:2. Detection by exposure to iodine vapors. Linearity was between 5 and 30 µg/zone. The LOD and LOQ were 2.3 and 6.7 µg/zone, respectively. Recovery was beween 76 and 85 %.

J. Planar Chromatogr. 33, 533-546 (2020). Review of chromogenic spray reagents for the detection and identification of organic pesticides by TLC and HPTLC. Specific applications for the analysis of organochlorine pesticides, organophosphate pesticides, carbamates and synthetic pyrethroids were described.

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.