CBS 115, 2-4 (2015). HPTLC of propolis tinctures and standards estrone, 17-estradiol, 17-ethinylestradiol, estriol, bisphenol A, 4-n-nonylphenol, and caffeic acid methyl ester on RP-18W with n-hexane – toluene – ethyl acetate 8:3:2 to a migration distance of 7 cm. For the HPTLC-pYES bioassay the plate was dipped into a yeast cell suspension and incubated for 3 h. Biodensitometric evaluation by fluorescence measurement at 365 nm with a cut-off filter of 400 nm. Elution of the bioactive zones with methanol – ammonium formate buffer (10 mM, pH 4, 49:1) into a ESI-MS. The LOD for 17-estradiol was 0.2 pg/zone and the LOQ 0.5 pg/zone. With this method estrogen effective substances can be detected with no or minimal sample preparation.

J. Planar Chromatogr. 29, 221-226 (2016). HPTLC of malathion (1) and fenthion (2) in apple and orange juice on silica gel with n-hexane – acetone 3:2. Detection by spraying with 6 % sodium azide, 0.25 % starch, pH 6.5 for (1) and 0.5 % sodium azide, 2 % starch,_x000D_ pH 6.0 for (2), followed by exposure to iodine vapors for 15 s. The chromatograms were scanned at 300 dpi. The hRF values for (1) and (2) were 51 and 48, respectively. Linearity was in the range of 1.0-7.3 μg/zone for (1) and 2.5-24.8 μg/zone for (2). Intermediate precisions were below 3.1 %. The LOD and LOQ were 242 and 807 ng/zone for (1) and 588 and 1960 ng/zone for (2), respectively. Recovery was in the range of 94.8-105.4 % for (1) and 84.2-104.0 % for (2).

J. Planar Chromatogr. 29, 417-422 (2016). HPTLC of kaempferol (1), quercetin (2), and gallic acid (3) in the herb Euphorbia humifusa on silica gel with chloroform – ethyl acetate – formic acid 26:22:5. Quantitative determination by absorbance measurement at 300 nm for (3) and 400 nm for (1) and (2). The hRF values for (1) to (3) were 18, 36 and 48, respectively. Linearities ranged 168-448 ng/zone for (1), 183-488 ng/zone for (2) and 179-476 ng/zone for (3). The intermediate precision was below 3.3 % (n=6). The LODs and LOQs were 16 and 53 ng/zone for (1), 7 and 23 ng/zone for (2) and 8-23 ng/zone for (3), respectively. Average recoveries were 96.1 % for (1), 98.3 % for (2) and 96.6 % for (3).

J. Planar Chromatogr. 29, 469-473 (2016). HPTLC of miconazole in creams on silica gel with ethyl acetate ‒ 25 % ammonia 50:1. Quantitative determination by absorbance measurement at 228 nm. The hRF value for miconazole was 57. Linearity was between 1250 and 3000 ng/zone. The intermediate precisions were below 2 % (n=6). Recovery ranged between 98.0 and 106.9 %.

J. Liq. Chromatogr. Relat. Technol. 40, 50-57 (2017). HPTLC of six nucleobases, guanosine (1), guanine (2), cytosine (3), adenine (4), uracil (5), and thymine (6) in sea buckthorn leaves on silica gel with dichloromethane – methanol – formic acid 160:45:16. Detection at UV 254 nm. The hRF values for (1-6) were 17, 23, 32, 38, 64 and 73, respectively. The bands were eluted using a TLC–MS interface and subjected to electrospray ionization-mass spectrometry (ESI-MS)._x000D_

J. Planar Chromatogr. 30, 181-187 (2017). HPTLC of guggulsterones E (1) and Z (2) in a polyherbal formulation containing Commiphora Muku on silica gel with toluene – ethyl acetate 4:1. Quantitative determination by absorbance measurement at 251 nm. The hRF values for (1) and (2) were 34 and 41. Linearity was between 0.2 and 1.2 μg/zone. LOD and LOQ were 43 and 132 ng/zone for (1) and 39 and 120 ng/zone for (2), respectively. The intermediate precision was below 2 % (n=3). Average recovery was 94.4 % for (1) and 97.7 % for (2).

J. Chromatogr. Sci. 54 (8), 1421-1427 (2016). Development of a simple, cost-effective and reliable method for quantification of naphthoquinones, found as natural red color pigments in roots of Arnebia benthamii (Wall. ex G.Don) I.M. Johnst., by HPTLC on silica gel with hexane – ethyl acetate – methanol 16:3:1. Determination of shikonin (hRf 37) and β,β-dimethylacryl shikonin (hRf 58) in the methanol extract by densitometry at 520 nm. The linearity was 0.1-8 µg/zone. The average recovery was >97 % for both and the intraday and interday precision for the quantification of naphthoquinones was good (%RSD <2.0 %). The LOD were 13 and 15 ng/zone for shikonin and β,β-dimethylacryl shikon and the LOQ were 39 and 44 ng/zone, respectively.

J. Chromatogr. Sci. 55 (5), 564-570 (2017). Determination of the chromatographic retention data for 13 new 5-arylidene-2,4-thiazolidinediones on cyano phase and RP-18 with 6 aqueous binary mobile phases modified with acetonitrile, methanol, ethanol, propanol, acetone and dioxane. Presentation of 3 attempts to find suitable quantitative structure–retention relationship (QSRR) models that quantify retention as a function of molecular descriptors. It was found that models built for RP-18 show generally better multiple R but are also mostly monoparametric with logP as the dominant descriptor. More informative from the standpoint of molecular interactions are QSRR models for cyano phase, and the quality of those models depends on the mobile phase modifier (the best was acetone and the worst propanol). It is suggested to consider extrapolated retention on cyano phase as alternative to standard RP-18 for further assessment of plasma protein binding, since all QSRR models use extrapolated retention as a property which is indirectly connected with plasma protein binding.