J. Liq. Chromatogr. Relat. Technol. 38, 1546-1554 (2015). HPTLC of aliskiren (1), amlodipine (2), and hydrochlorothiazide (3) on silica gel with ethyl acetate - methanol - ammonia 375:140:11. Quantitative determination by absorbance measurement at 229 nm. The hRF values for (1) to (3) were 43, 29 and 65, respectively. Linearity was in the range of 1500-5250 ng/zone for (1), 50-175 ng/zone for (2) and 125-432 ng/zone for (3). LOD and LOQ were 133 and 404 ng/zone for (1), 14 and 43 ng/zone for (2) and 12 and 36 ng/zone for (3), respectively. The intermediate precision was below 1.5 % (n=6). Recovery was found in the range of 99-101 %, 99-100 %, and 100-101 % for (1) to (3), respectively.

Food Chem. 214, 162-168 (2017). HPTLC of cinnamic acid (1), ferulic acid (2), caffeic acid (3) and flavonoid-glycosides (4) in the grains of Kodo millet (Papsalum scrobiculatum) on silica gel with ethyl acetate – formic acid – water 30:2:2. Detection by exposure to iodine vapor. The hRF values for (1) to (4) were 52, 15, 7 and 10, respectively.

J. Planar Chromatogr. 29, 145-147 (2016). HPTLC of amino acids in seed cotyledons and seed coats from two types of legumes: black-eyed beans (Vigna unguiculata) and red kidney beans (Phaseolus vulgaris) on silica gel with n-butanol – glacial acetic acid – water 12:3:5. Detection by spraying with ninhydrin reagent 0.2 g/100 mL in ethanol, followed by heating at 80-100 °C for 5 min. The hRF values of essential and nonessential amino acids were determined and ranged between 13 and 62.

J. Chromatogr. Sci. 52 (9), 1089-1094 (2014). HPTLC of the anticancer compound nimbolide in different parts of Azadirachta indica and its dosage form on silica gel with n-hexane – ethyl acetate – acetic acid 30:20:1 (migration distance 68 mm, chamber saturation time 2 min), detection by spraying with 5 % sulfuric acid in methanol, quantification after absorption measurement at 515 nm. Validation by investigation of the (A) hRf value of nimbolide (43), (B) linearity range (200–1400 ng/zone, r2=0.99968), (C) LOD (70 ng/zone) and LOQ (200 ng/zone), (D) recovery (97.5 %, n=3), and (E) specificity (comparison of hRf value and UV/vis absorption spectrum with the standard).

J. of Chromatogr. A 1415, 155-160 (2015). Presentation of a technique for direct analysis of raw samples by TLC coupled with electrospray ionization mass spectrometry (ESI-MS) instead of conventional MS analysis, which for raw samples commonly requires time-consuming and laborious sample pretreatment and separation using HPLC or GC. The analytes of interest could be extracted, ionized and detected by ESI-MS with much reduced matrix interference because the interfering compounds were retained by the sorbent material of the TLC plate. Demonstration by applying in direct analysis of samples containing common interfering compounds, e.g. salts and detergents. Rapid detection and quantification of target analytes in raw samples showed that the TLC-ESI-MS method was simple, rapid, efficient and could be effectively applied in offline and online separation and detection of different components in raw samples, e.g. plant extracts.

J. Agric. Food Chem. 64, 8246-8253 (2016). HPTLC of ricinoleic acid in Secale cornutum on silica gel with cyclohexane – diisopropyl ether – formic acid 86:14:1. Detection by dipping into a solution of n-hexane – paraffin oil 2:1. Quantitative determination by fluorescence measurement at 280/>340 nm. The hRF value for ricinoleic acid was 33. Linearity was between 0.1 and 1.8 ng/zone. The intermediate precisions were below 3 % (n=5). The LOD and LOQ were 0.06 and 0.2 ng/zone, respectively.

J. Planar Chromatogr. 29, 474-476 (2016). HPTLC of methamphetamine in Ya-Ba tablets on silica gel with methanol ‒ ammonium 200:3. Quantitative determination by absorbance measurement at 259 nm. The hRF value was 35. Linearity was between 600 and 3000 μg/zone. The intermediate precision was 11.2 % (n=3). The LOD and LOQ were 153 and 463 μg/zone, respectively. Average recovery was 102.3 %.

J. Chromatogr. A 1468, 228-235 (2016). Development and validation of a rapid and simple screening method by HPTLC for antioxidant activity in samples of 16 algal species collected from local Victorian beaches. Quantification of fucoxanthin, one of the most abundant marine carotenoids directly from the HPTLC plates before derivatization either with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical or ferric trichloride to analyze antioxidants in marine algae, based on their ability to chelate iron ions or to scavenge non-biological stable free radical, respectively. Classification of algae species into 5 groups according to the chemical/antioxidant profiles by principal component analysis of obtained HPTLC fingerprints. The investigated brown algae samples were rich in non-polar and moderate-polar and phenolic compounds with antioxidant activity, while most of the phenolic iron chelators showed free radical scavenging activity. Strong positive and significant correlations between total phenolic content and DPPH radical scavenging activity showed that phenolic compounds, including flavonoids are the main contributors of antioxidant activity in these species, which could be considered for future applications in medicine, dietary supplements, cosmetics or food industries. Discussion of the advantages of the proposed methods in terms of screening for antioxidants and quantification of antioxidant constituents in complex mixtures using the flexible and versatile standard HPTLC system in the drug discovery, and the possibility of using the method for the bioassay-guided isolation of unknown natural antioxidants and subsequent identification if combined with spectroscopic identification.