J. Planar Chromatogr. 36, 77-87 (2023). HPTLC of guggulsterones E (1) and Z (2) in AYUSH guggul formulations on silica gel with n-hexane - ethyl acetate 1:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) and (2) were 41 and 48, respectively. Linearity was in the range of 6-24 µg/mL for (1) and 13-42 µg/mL for (2). Intermediate precisions were below 2 % (n=6). LOD and LOQ were 3 and 5 µg/mL for (1) and 2 and 5 µg/mL for (2), respectively. Recovery was between 93.3 and 95.6 % for (1) and 95.0 and 97.8 % for (2).

J. Planar Chromatogr. 36, 55-61 (2023). HPTLC of catechin (1) and andrographolide (2) in Himalaya PartySmart capsule on silica gel with chloroform - acetone - formic acid 14:6:1. Quantitative determination by absorbance measurement at 259 nm. The hRF values for (1) and (2) were 41 and 78, respectively. Linearity was in the range of 500-2500 ng/zone for (1) and 250-1250 ng/zone for (2). Intermediate precisions were below 2 % (n=3). LOD and LOQ were 205 and 621 ng/zone for (1) and 134 and 406 ng/zone for (2), respectively. Recovery was between 97.6 and 102.0 % for (1) and 96.7 and 104.1 % for (2).

J. Planar Chromatogr. 36, 71-76 (2023). HPTLC of melamine (1), formaldehyde (2) and genotoxins (3) in bamboo tableware on silica gel with iso-propanol - ethyl acetate - water 10:5:6 for (1), chloroform - dichloromethane - diethyl ether 4:5:6 for (2) and (3). Genotoxin analysis by spraying with Salmonella suspension followed by spraying FDG substrate solution and incubation at 37 °C for 15 min. Qualitative analysis at 254 nm and densitometric absorption measurement at 202 nm for (1) to (3).

J. Planar Chromatogr. 35, 585-591 (2022). HPTLC of betulinic acid in the fruit extracts of Ziziphus mauritiana and Ziziphus nummularia on silica gel with petroleum ether - ethyl acetate - toluene 7:2:1. Detection by dipping into an anisaldehyde - sulfuric acid reagent, followed by heating at 110 °C for 5 min. Quantitative determination by absorbance measurement at 580 nm. The hRF value for betulinic acid was 73. Linearity was between 2 and 10 µg/zone. Intermediate precisions were below 2 % (n=6). LOD and LOQ were 0.4 and 1 µg/zone, respectively. Average recovery was 99.5 %.

J. Planar Chromatogr. 35, 571-577 (2022). HPTLC of rosmarinic acid (1), quercetin (2), glycyrrhizin (3) and betulinic acid (4) in polyherbal immunostimulant formulation on silica gel with ethyl acetate - toluene - methanol - formic acid 14:2:1:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) to (4) were 68, 74, 14 and 87, respectively. Linearity was between 400 and 1900 ng/zone for (1) to (4). Intermediate precisions were below 2 % (n=6). LOD and LOQ were 4 and 11 ng/zone for (1), 1 and 3 ng/zone for (2), 12 and 36 ng/zone for (3) and 0.3 and 0.9 ng/zone for (4), respectively. Average recovery was 99.1 % for (1), 99.8 % for (2), 99.8 % for (3) and 100.3 % for (4).

J. Planar Chromatogr. 35, 617-625 (2022). HPTLC of montelukast (1) and loratadine (2) mixture in spiked human plasma on silica gel with chloroform - ethyl acetate 4:1. Quantitative determination by absorbance measurement at 280 nm. The hRF values for (1) and (2) were 17 and 39, respectively. Linearity was between 48 and 300 ng/zone for (1) and 90 and 600 ng/zone for (2). Intermediate precisions were below 3 % (n=3). LOD and LOQ were 9 and 28 ng/zone for (1) and 22 and 67 ng/zone for (2), respectively. Recovery was between 99.6 and 102.8 % for (1) and (2).

J. Planar Chromatogr. 35, 635-641 (2022). HPTLC of leflunomide on silica gel with toluene - chloroform - ethanol 2:2:1. Quantitative determination by absorbance measurement at 266 nm. The hRF value for leflunomide was 53. Linearity was between 100 and 600 ng/zone. Intermediate precisions were below 2 % (n=6). LOD and LOQ were 4 and 13 ng/zone, respectively. Recovery was between 100.8 and 103.8 %.

J Chrom Sci, bmad055 (2022). Standards of antiglycemic drugs were metformin hydrochloride (S1, a biguanide), glibenclamide (S2 = glyburide, a sulfonylurea), pioglitazone hydrochloride (S3, a thiazolidinedione), repaglinide (S4, a glinide). Samples were methanolic solutions of commercial tablets of S1 with each of the other molecules. The following method was developed by a software-assisted AQbD approach (analytical quality by design): (1) Several TLC separations were tried with toluene together with other solvents and with acidic or basic modifiers, with also variations of 24 method or instrumental parameters. (2) Principal component analysis (PCA) was performed in order to identify two principal components (PCs) responsible for 98 % of the observed variations: namely, resolution and tailing factor. Three critical method parameters (CMPs) had a statistically significant impact on the PCs: mobile phase (MP) composition, ammonium acetate concentration in MP, and saturation time. (3) To optimize these CMPs, the Box–Behnken design was implemented in 15 software-proposed experiments; the impacts of the 3 CMPs on the 2 PCs were evaluated by ANOVA, multiple regression analysis, and 2D and 3D contour plots. (4) The optimal CMPs ranges were determined by defining a MODR (method operable design region) on the superposed contour plots, and one TLC condition was selected as analytical control point.
TLC on silica gel pre-washed with 10 mL methanol, dried and activated 10 min at 100° C. Separation with toluene – ethyl acetate – methanolic solution of 4 % ammonium acetate 7:7:6 after 15 min pre-saturation with 35 % relative humidity. Absorption emasurement at UV 254 nm. The hRF values were 13 for S1, 72 for S2, 82 for S3, 38 for S4. LOQ were 263, 387, 73 and 35 ng/zone, respectively. Linearity range was 25–75 µg/zone for S1, 100–300 ng/zone for S2 and S4, 750–2250 ng/zone for S3. Intermediate precision was below 2 %. For accuracy tests, recovery rates were between 97.6–101.4 %.