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.

(Xi Xian) by a validated high-performance thin-layer chromatographic method. J. Planar Chromatogr. 30, 516-520 (2017). HPTLC of chlorogenic acid (1) and caffeic acid (2) in the leaves of Siegesbeckia orientalis on silica gel with toluene ‒ ethyl acetate ‒ formic acid ‒ methanol 30:30:8:3. Quantitative determination by absorbance measurement at 366 nm. The hRF values for (1) and (2) were 19 and 83, respectively. Linearity was between 200 and 600 ng for (1) and (2). LOD and LOQ were 20 and 40 ng/zone for (1) and 59 and 120 ng/zone for (2), respectively. The intermediate/interday/intra-day precisions were below 3 % (n=3). Recovery was 99.0 %.

J. Chromatogr. A 1497, 155-163 (2017). Development of a planar yeast estrogen screen for the determination of estrogen active compounds. Introduction of resorufin-β-D-galactopyranoside, providing the orange fluorescing resorufin after enzymatic cleavage, as the planar yeast estrogen screen (pYES) substrate to determine estrogen active compounds (EAC). For samples containing blue fluorescent components, this substance is better suited than the generally employed substrate 4-methylumbelliferyl-β-D-galactopyranoside, which delivered blue fluorescing 4-methylumbelliferone after enzymatic cleavage by the YES reporter β-D-galactosidase. The mean LOD and LOQ was 3.5 and 6.5 pg/zone for 17β-estradiol (1) and 17α-ethinylestradiol (2), respectively; recoveries were close to 100% for (1) and (2) from spiked water samples in a concentration range of 2–20 ng/L.

J. Chromatogr. Sci. 56 (4), 376-381 (2018). Investigation of the lipophilicity of new anticancer active 10-substituted 1,6- and 3,6-diazaphenothiazines using RP TLC. Determination of their lipophilicity (RM0 and log PTLC) with mixtures of acetone and Tris buffer as mobile phases. The obtained results showed significant intercorrelation between RM0 and the specific hydrophobic surface area b, revealing congeneric classes of diazaphenothiazines. Transformation of the parameter RM0 into parameter log PTLC by use of the calibration curve. Comparison of the parameter log PTLC with computationally calculated lipophilic parameters log Pcalcd. Discussion of the lipophilicity with the structure elements and correlation with molecular descriptors, ADME properties and in vitro anticancer activities.

J. Planar Chromatogr. 31, 143-149 (2018). HPTLC of stigmasterol (1), β-sitosterol (2), campesterol (3) and ergosterol (4) in Heteropogon contortus on silica gel with toluene – methanol – formic acid 90:10:3. Detection by spraying with anisaldehyde sulfuric acid followed by heating at 110-120 °C for 4-5 min. Quantitative determination by absorbance measurement at 530 nm. The hRf values for (1) to (4) were 23, 13, 39 and 28, respectively. Linearity was in the range of 2-12 ng/zone for (1) to (4). The LOD and LOQ were 50 and 200 pg/zone for (1), 13 and 40 pg/zone for (2), 86 and 260 pg/zone for (3) and 20 and 60 pg/zone for (4), respectively. Recovery was in the range of 98.4 and 99.6 % for (1) to (4).

J. Agric. Food Chem. 65, 8773-8778 (2017). HPTLC of aflatoxin B1 on silica gel with chloroform – ethyl acetate 4:1. Quantitative determination by fluorescence measurement at 366/>400 nm.

J. Chromatogr. A 1579, 115-120 (2018). Description of a fast method for on-site detection of aflatoxins in moldy agricultural products using TLC combined with surface-enhanced Raman spectroscopy (TLC-SERS). On-site identification of four aflatoxins separated by TLC employing a small portable Raman spectrometer with gold colloids as the SERS-active substrate. Investigation of the application of the TLC-SERS technique to on-site qualification and quantification of aflatoxins in levels as low as 1x10−6 M shows that the technique has high sensitivity and selectivity to the object of interest and suits complex matrixes, such as the extracts from moldy peanuts. The method is suitable for fast on-site screening of aflatoxins in various agricultural products.

leaves. J. Planar Chromatogr. 31, 377-381 (2018). HPTLC of ursolic acid and β-sitosterol in the leaves of Paederia foetida on silica gel with toluene ‒ ethyl acetate ‒ formic acid 80:20:1. Detection by spraying with anisaldehyde–sulfuric acid reagent, followed by heating at 110 °C for 1 min. Quantitative determination by absorbance measurement at 550 nm. The hRF values for (1) and (2) were 22 and 38, respectively. Linearity was between 100 and 500 ng for (1) and (2). LOD and LOQ were 40 and 121 ng for (1) and 50 and 152 ng for (2). The intermediate precision was <2 % (n=3). Recovery ranged from 97.2 % to 99.2 % for (1) and 98.0 % to 99.2 % for (2).