J. Chromatogr. A 1530, 185-191 (2017). Development of a new spray-on method for applying yeast cells to HPTLC plates, leading to a much higher sensitivity of the planar yeast estrogen screen (p-YES), which can serve as a highly valuable and sensitive screening tool for the detection of estrogenic compounds in various sample matrices such as water and wastewater, personal care products and foodstuff. HPTLC of sample constituents and direct detection of estrogenic compounds by spraying with yeast cells. This resulted in much sharper signals compared to those in previous publications. Satisfying results were achieved using cultures with cell densities of 1000 FAU with reduced signal broadening, thus lower LOQ for estrogenic compounds, e.g. estrone 2 pg/zone, 17β-estradiol 0.5 pg/zone, 17α-ethinylestradiol 0.5 pg/zone and estriol 20 pg/zone. Demonstration of the possibility of the method to characterize profiles of estrogenic activity of wastewater samples with high quality and reproducibility by using native samples from wastewater or even surface water directly applied on HPTLC plates without the need for prior sample treatment.

J. Sep. Sci. 41, 518-524 (2018). HPTLC of withanolide S in the leaves of Withania somnifera on silica gel with dichloromethane – toluene – methanol – acetone 15:2:1:1. Detection by spraying with sulfuric acid reagent (180 mL methanol with 20 mL sulfuric acid) followed by heating at 120 °C for 10 min. Quantitative determination by fluorescence measurement at 365/>400 nm. The hRF value for withanolide S was 7. Linearity was between 15 and 500 μg/mL. LOD and LOQ were 30 and 92 μg/mL. The intermediate/interday/intra-day precisions were below 2 % (n=3). Recovery was in the range of 94.6 and 99.1 %.

J. Chromatogr. A 1560, 78-81 (2018). The minimalistic software quanTLC is open-source, online, intuitive to use and tailored to planar chromatography. It supports common image file formats for chromatogram upload and allows the quantitative evaluation of samples quickly, involving steps of videodensitogram extraction, preprocessing, automatic peak integration, calibration, statistical data analysis, reporting and data export. The default options for each step are suitable for most analyses, but can be tuned for export of the data in each step and for further processing in other software. Demonstration of the software capabilities on the example of a lipophilic dye mixture separation in a one-minute video user manual. Verification of the quantitative results by comparison with those obtained by commercial videodensitometry software and opto-mechanical slit-scanning densitometry. The software is directly accessible and online useable without installation.

J. Chromatogr. Sci. 56, 518-523 (2018). Presentation of a validated method for the quantitation of dihydrokaempferol-4′-O-glucopyranoside. This flavanonol glucoside is a marker compound in the flower of Alcea rosea L. with significant antioxidant and anticancer activity against the HepG-2 cell line. HPTLC on silica gel with ethyl acetate – methanol – water – acetic acid 600:100:80:3 over 70 mm with chamber saturation for 30 min. Quantitative determination by absorbance measurement at 295 nm. The amount of dihydrokaempferol-4′-O-glucopyranoside in the flowers of A. rosea was 0.733 g/100 g and 0.928 g/100 g after maceration and sonication for 15 min, respectively. Linearity was in the concentration range of 0.9-3.6 µg/zone. The %RSD of the intra-day and inter-day precision was 0.2–1.5 % and 0.5–1.7 %, respectively. The LOD and LOQ were 312 ng/zone and 947 ng/zone, respectively.

by high-performance thin-layer chromatography method. J. Planar Chromatogr. 31, 337-342 (2018). HPTLC of betulinic acid (1), oleanolic acid (2) and lupeol (3) in Achyranthes aspera on silica gel with benzene – ethyl acetate – formic acid 679:227:94 for (1), n-hexane – ethyl acetate – glacial acetic acid 40:20:1 for (2) and n-hexane – ethyl acetate 4:1 for (3). Detection by spraying with anisaldehyde sulfuric acid reagent for (1) and (2) and ceric ammonium sulfate for (3), followed by heating at 105-110°C for 5-10 min. Quantitative determination by absorbance measurement at 530 nm for (1) and (2) and 366 nm for (3). The hRF values for (1) to (3) were 79, 46 and 44, respectively. Linearity was between 2-10 μL/zone. LOD and LOQ were 1 and 4 ng/zone for (1), 1 and 3 ng/zone for (2), and 2 and 5 ng/zone for (3), respectively.

Braz. J. Pharm. Sci. 54, 1-10 (2018). HPTLC of gliquidone on silica gel with chloroform – cyclohexane – glacial acetic acid 6:3:1. Quantitative determination by absorbance measurement at 254 nm. The hRF values for gliquidone and degradation products I, II and III were 60, 1, 24 and 52, respectively. Linearity was between 2 and 20 μg/zone. LOD and LOQ were 261 and 791 ng/zone. The intermediate precision was <2 % (n=3). Average recovery was 100.0 %.

Proc. Intern. Symposium on TLC with special Emphasis on OPLC, Szeged, 28 (1984). OPLC (OPTLC) of leu-, gly-, glu-, his-, ser-, tyr-, met on silica with 1) chloroform - ethanol - acetic acid 90.10:2, followed by a second run with dichloromethane-ethyl acetate 9:1. Detection by UV. Fluorescence scanning (excitation at 275 nm). Detection limit 50 ng. Sequencing of some polypeptides from the N-terminus.

Method for the analysis of aflatoxins, ochratoxin A, zearalenone, vomitoxin and secalonic acid D. J.A.O.A.C. 67, 963-967 (1984). TLC of aflatoxins on silica with ether - methanol - water 96:3:1 and of ochratoxin with toluene - acetic acid 95:5. Quantification by fluorescence measurement. Minimum detectable amount for aflatoxins: less than 0.5 ng/g; ochratoxin: l0 ng/g.