J. Planar Chromatogr. 29, 66-71 (2016). Controlled gas phase HPTLC of benzoic acids (benzoic o-, m-, p-hydroxybenzoic, 2,4-dihydroxybenzoic, nitrobenzoic, o-, m-, p-aminobenzoic, o- and p-chlorobenzoic, o- and p-bromobenzoic, and o-phthalic acids) on silica gel, RP-18 and polyamide-11 with hexane – 2-propanol 19:1. This variant was based on the use of a gas phase (carbon dioxide, ammonia or acetic acid) moving over the TLC plate for regulation of the stationary and mobile phases. The most considerable change in the retention of benzoic acid derivatives was observed for normal-phase plates due to change of acid-base properties of stationary and mobile phases.

Pharm. Res. 33, 1587-1601 (2016). HPTLC study of the cleavability of the disulfide bond in a conjugate siRNA-S-S-PE (incubated in 10 mM glutathione at 37 °C for 4 h) on silica gel with chloroform – methanol 4:1. Detection by spraying with molybdenum blue dye for the cleaved phospholipids. This test confirmed the potential utility of this system for siRNA delivery in vivo.

CBS 114, 9-10 (2015). HPTLC of phosphodiesterase type 5 inhibitors Viagra (sildenafil), Levitra (vardenafil), Cialis (tadalafil) and their analogs (hydroxyacetildenafil, homosildenafil, thiohomosildenafil, acetildenafil, acetaminotadalafil, propoxyphenyl, hydroxyhomosildenafil, hydroxyhomosildenafil, and_x000D_
hydroxythiohomosildenafil) on silica gel with t-butyl methyl ether – methanol – 28 % ammonia 20:2:1 with chamber saturation, migration distance 70 mm. Detection under UV 254 and 366 nm. Densitometric evaluation by absorbance measurement at 232 nm. Identification of the substances based on their hRf values and distinctly different UV spectra.

J. Planar Chromatogr. 29, 184-189 (2016). HPTLC of (±)-etodolac mixed with L-Trp 1:1 as chiral inducing reagent on silica gel with acetonitrile – dichloromethane – methanol 3:1:2. Detection by using iodine vapor. The hRF values for (-)- and (+)-etodolac were 33 and 62, respectively.

J. Planar Chromatogr. 29, 341-346 (2016). HPTLC of artemisinin in the seeds of Artemisia annua on silica gel with n-hexane ‒ ethyl acetate ‒ acetic acid 20:10:1. Detection by dipping into anisaldehyde reagent (glacial acetic acid ‒ sulfuric acid ‒ anisaldehyde 50:1:0.5) followed by heating at 110 °C for 5 min. Quantitative determination by absorbance measurement at 540 nm. The hRF value for artemisinin was 43. Linearity was between 200 and 1000 ng/zone. The intermediate precision was below 0.7 % (n=3). The LOD and LOQ were 30 and 80 ng/zone, respectively. Recovery ranged from 82.9 to 87.1 %.

J. Planar Chromatogr. 29, 453-461 (2016). HPTLC of chlorzoxazone (1) and diclofenac potassium (2) in the presence of the nephrotoxic chlorzoxazone degradation product_x000D_
2-amino-4-chlorophenol (3) on silica gel with chloroform ‒ ethanol ‒ triethylamine 90:10:1. Quantitative determination by absorbance measurement at 230 nm. The hRF values for (1) to (3) were 63, 35 and 42, respectively. Linearities ranged between 1.5-5 μg/zone for (1), 0.5-4 μg/zone for (2) and 0.4-4 μg/zone for (3). The intermediate precisions were below 1.3 % (n=3). The LODs and LOQs were 320 and 980 ng/zone for (1), 140 and 450 ng/zone for (2) and 120 and 370 ng/zone for (3), respectively. Average recoveries were 100.2 % for (1), 99.3 % for (2) and 99.4 % for (3).

J. Planar Chromatogr. 30, 97-105 (2017). Review of current applications of room temperature ionic liquids on planar chromatography as mobile phases. Methylammonium, ethylammonium, propylammonium, isopropylammonium, butylammonium, s-butylammonium, dipropylammonium, tributylammonium were reported to be used as replacements for organic solvents in binary systems. As mobile phase additives, room temperature ionic liquids were used for the separation of peptides and basic drugs in both normal phase and reversed phase chromatography with an emphasis on their role as masking agents. The authors suggested that given the large number of possible cation and anion combinations, systematic methods that characterize solvation properties for both ionic liquids and organic solvents are required.

J. Ethnopharmacol. 204, 26-35 (2017). HPTLC of quercitrin (1), isoquercitrin (2), quercitrin-3-O-β-D-xylopyranosyl-α-L-rhamnopyranoside (3) on silica gel with ethyl acetate – formic acid – acetic acid – water 100:11:11:26. Detection by spraying with NEU`s reagent (diphenylborinic acid 2-aminoethylester, natural product reagent), followed by drying at 110 °C for 2 min. Quantitative determination by absorbance measurement at 265 nm. LOD and LOQ were 31 ng/zone and 75 ng/zone for (2). Recovery was between 99.8 and 101.1 % for (2). Intermediate precision was <2 % (n=3).