J Pharm Bioallied Sci 15(Suppl.2), S948-S951 (2023). Sample was the ethyl acetate fraction of an ethanolic extract of Viola odorata aerial parts (Violaceae). Standards were coumarinic compounds: esculetin (1) and umbelliferone (2). TLC and HPTLC on silica gel with toluene – ethyl acetate – formic acid 5:4:1. Visualization under UV 254 nm and 366 nm; densitometric scanning at 366 nm. Both (1) and (2) were found in the extract (hRF values 30 and 53, respectively, in TLC). Alternative mobile phases were also tested (TLC only): toluene – ethyl acetate 1:1 (hRF values 47 and 68) and chloroform – methanol 97:3 (hRF values 20 and 41).

J. Liq. Chromatogr. Relat. Technol. 45, 217-225 (2022). HPTLC of capecitabine (1) and thymoquinone (2) on silica gel with toluene - methanol 3:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for (1) and (2) were 52 and 86, respectively. Intermediate precisions were below 2 % (n=3). LOD and LOQ were 17 and 54 ng/zone for (1) and 39 and 119 ng/zone for (2), respectively. 

J. Liq. Chromatogr. Relat. Technol. doi.org/10.1080/10826076.2023.2216780
2023). HPTLC of haloperidol, risperidone, aripiprazole, olanzapine, and quetiapine on RP-18, CN and amino phase with acetonitrile-water in various concentrations (from 75 to 90 % acetonitrile with 0.2 % formic acid in each case). Detection under UV light at 254 nm. Lipophilicity parameters (mRM, RM0) were determined from the hRF values for estimation of enzyme inhibitory activity and prediction of antipsychotic action of compounds.

 J. Pharmacogn. Phytochem. 12(1), 6-14 (2023). TLC silica gel layers were used to monitor the purification through column chromatography (CC) of a chloroform fraction of the methanolic root bark extract of Rauvolfia vomitoria (Apocynaceae). Mobile phases were petroleum ether – ethyl acetate 4:1 (MP1), dichloromethane – methanol 20:1 (MP2), and dichloromethane – methanol 15:1 (MP3). Visualization under UV 254 nm. Preparative TLC on thicker silica gel was performed on two subfractions: (A) with dichloromethane – methanol 100:7 for the isolation of the methyl esters of eudesmic acid and of trimethoxycinnamic acid (hRF values 35 and 28, respectively, in MP1); (B) with MP2 for the isolation of an indole alkaloid: kumujan B (= 1-carbomethoxy-β-carboline, hRF value 40 in MP2). Other indole alkaloids were isolated through CC: ajmaline, mauensine and reserpine (hRF values 35, 13 and 47, respectively, in MP3).

J. Planar Chromatogr. 36, 89-97 (2023). HPTLC of remogliflozin etabonate (1) and metformin hydrochloride (2) in bulk and tablet formulation on silica gel with ethyl acetate - methanol - toluene - formic acid 5:2:9:4 (NP) and on RP-18 with water - methanol - glacial acetic acid 5:3:2 (RP). Quantitative determination by absorbance measurement at 226 nm for both methods. The hRF values for (1) and (2) were 56 and 10 for NP and 15 and 88 for RP, respectively. Linearity was in the range of 200-1200 ng/zone for (1) and 1000-6000 ng/zone for (2) in both NP and RP. Intermediate precisions were below 2 % (n=3). LOD and LOQ were 18 and 54 ng/zone for (1) and 105 and 318 ng/zone for (2) in NP and 17 and 51 ng/zone for (1) and 115 and 348 ng/zone for (2) in RP. Recovery was in the range of 100.3-100.8 % for (1) and 100.2-100.7 % for (2) in NP and 100.3-100.7 % for (1) and 100.3-100.8 % for (2) in RP.

J. Planar Chromatogr. 36, 63-70 (2023). HPTLC of quercetin (1), berberine (2), rutin (3) and curcumin (4) in a polyherbal formulation on silica gel with toluene - ethyl acetate - methanol - formic acid 10:6:4:1. Quantitative determination by absorbance measurement at 366 nm for (1) to (3) and 425 nm for (4). The hRF values for (1) to (4) were 57, 30, 9 and 66, respectively. Linearity was in the range of 500-3000 ng/zone for (1), 200-700 ng/zone for (2), 1000-6000 ng/zone for (3) and 100-350 ng/zone for (4). Intermediate precisions were below 2 % (n=6). LOD and LOQ were 119 and 362 ng/zone for (1), 33 and 100 ng/zone for (2), 248 and 750 ng/zone for (3) and 14 and 42 ng/zone for (4). Recovery was between 95 and 102 % for (1) to (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 %.