J. Liq. Chromatogr. Relat. Technol. 41, 83-86 (2018). TLC of gardenia blue in foods on RP-18 with 0.2 % trifluoroacetic acid – acetonitrile – ethanol 1:2:3 and on cellulose with acetone – 3-methyl-1-butanol – water 6:5:5. The hRf values of gardenia blue coloring were 35, 18 and 13 on RP-18 and 72, 56 and 48 on cellulose layer.

J. Chromatogr. A 1577, 101-108 (2018). In order to overcome the difficulty of the interpretation of the MS signals present at a low intensity for unknown degradation products or impurities, a new strategy and open-source software called eicCluster was developed. It offered unsupervised machine learning algorithms and powerful interactive visualization tools that made data processing fast and intuitive. The low-intensity HPTLC-HRMS signals were highlighted in a stressed formulation by using eicCluster. Thus, even compound ions present at low intensities were separated in subclusters from background signals (in silico highlighting). The respective preprocessing led to intensity-agnostic signals and the t-SNE algorithm clustered mass signals based on their similarity. The resulting 2D maps allowed a new view on the data set to such low-intensity target molecules in complex mixtures. Moreover, the targeted on-surface synthesis of degradation products (in situ highlighting) was shown to support a fast structure elucidation, when standards are not commercially available. It allowed a better understanding of the proposed degradation reactions in the formulation. Comparison with the results of stressed samples as well as the proposed degradation products of on-surface synthesis proved that in silico and in situ signal highlighting substantially eased structure elucidation and data processing.

J. Ethnopharmacol. 233, 141-147 (2019). HPTLC of gentiopicrin in the dried roots and rhizomes of Gentiana scabra on silica gel with ethyl acetate – ethanol – water 8:2:1. Detection by spraying with chromogenic reagent (acetic acid – sulfuric acid – p-anisaldehyde 100:2:1). Qualitative evaluation at UV 254 nm. The hRF value for gentiopicrin was 58.

J. Chromatogr. A 1572, 137-144 (2018). Development of a method for the analysis of anthocyanes within the foodstuffs of plant origin by TLC on RP-18 phase (which ensures mixed-mode retention mechanism with the localized adsorption on the non-bonded silanols) with acetic acid as the mobile phase component, using two anthocyanins (cyanin and keracyanin) and two anthocyanidins (pelargonidin and delphinidin) as phytochemical standards. By triple development, distinct and symmetrically shaped chromatographic zones were obtained. Further analysis of the products of hydrolytic degradation of the test anthocyanins by MS. Identification of the hydrolytically split fractions by using the p-aminobenzoic acid reagent. Investigation of the calibration curves for cyanin, keracyanin, pelargonidin and delphinidin, and the respective LOD and LOQ values. Application of the method to identify and quantify cyanin, keracyanin, pelargonidin and delphinidin in selected alimentary products (syrups, juices and herbal infusions).

J. AOAC Int. 101, 1031-1041 (2018). HPTLC of zofenopril calcium (1) and hydrochlorothiazide (2) in the presence of the hydrochlorothiazide impurities chlorothiazide (3) and salamide (4) on silica gel with ethyl acetate – glacial_x000D_ acetic acid – triethylamine 100:1:1. Quantitative determination by absorbance measurement at 270 nm. The hRF values for (1) to (4) were 34, 44, 25 and 64, respectively. Linearity ranged between 0.5-10.0 μg/zone for (1), 0.2-4.0 μg/zone for (2), 0.05-1.4 μg/zone for (3) and 0.05-1.0 μg/zone for (4). LOD and LOQ were 20 and 50 ng/zone for (3) and (4). The intermediate precision was <2 % (n=3). Average recovery was 100.0 % for (1), 99.6 % for (2), 99.5 % for (3) and 99.2 % for (4).

(TLC in the laboratory of a chemist's shop.) Dtsch. Apoth. Ztg. 125, 1223-1232 (1985). Identification of vitamins (A,D,E), salicylic acid derivatives, passiflorae herba, foliae rubus, solidago virgaurea, veronica officinalis and flores primulae by TLC. Detailed description including color pictures to facilitate the interpretation of TLC results.

Then chromatography in second direction with chloroform - acetone 8:2. Detection by UV and iodine vapor.

TLC on silica with chloroform -methanol - acetic acid - water 80:10:8:2. Detection by spraying with 2 % eosin in ethanol and by UV.