by validated high-performance thin-layer chromatography-densitometric method. J. Planar Chromatogr. 27, 362-366 (2014). HPTLC of (1) piperine and (2) piperlongumine in the fruits of Piper longum on silica gel with n-hexane – ethyl acetate 4:1. Quantitative determination by absorbance measurement at 290 nm. The hRF values of (1) and (2) were 24 and 54, respectively. Linearities were between 100 and 500 ng/zone for (1) and between 200 and 1000 ng/zone for (2). The intermediate precisions were below 1 % (n=6) for both, (1) and (2). The LOD and LOQ were 40 and 80 ng/zone for (1) and 90 and 200 ng/zone for (2), respectively. Average recoveries for (1) and (2) were 99.2 and 99.3 %, respectively.

J. Planar Chromatogr. 27, 428-430 (2014). HPTLC of (1) tretinoin and (2) isotretinoin on silica gel with toluene – ethyl acetate – methanol 16:2:1. Quantitative determination by absorbance measurement at 334 nm. The hRF values of (1) and (2) were 27 and 38, respectively. Linearity was in the range of 30-70 ng/zone for (1) and (2). The intermediate precision was below 1 % (n=6) for (1) to (2). The LOD and LOQ were 10 and 20 ng/zone for (1) and 20 and 30 ng/zone for (2). Recovery for (1) and (2) were in the range of 95-102 %.

J. Beijing Univ. Agr. 29 (2), 33-35 (2014). Qishen Koufuye oral solution is a TCM preparation for the treatment of chronic gastritis, gastric and duodenal ulcer, etc. For quality control, TLC on silica gel (1) for Astragalus membranaceus (Fisch.) Bunge. and astragaloside A with ethyl acetate – butanone – formic acid – water 5:3:1:1, detection by spraying with 10 % sulfuric acid in ethanol and heating at 105 °C for 5 min, evaluation under white light and at UV 366 nm; (2) for Atractylodes macrocephala Koidz. with cyclohexane - ethyl acetate 7:3, detection by spraying with 5 % p-dimethylaminobenzaldehyde in sulfuric acid – ethanol 1:4 and heating at 105 °C for 5 min, evaluation at UV 366 nm; (3) for Glycyrrhiza uralensis Fisch. with ethyl acetate – formic acid – glacial acetic acid – water 15:1:1:2, detection by spraying with 10 % sulfuric acid in ethanol and heating at 105 °C for 5 min, evaluation under white light and at UV 366 nm. Identification of Radix Codonopsis by HPLC.

Food Chem. 187, 460-468 (2015). HPTLC-direct bioautography of bioactive compounds in the extracts of cold-pressed hemp (1), flax (2) and canola (3) seed oil on silica gel with toluene - ethyl acetate - formic acid - water 15:30:5:3 for (2) and toluene - ethyl acetate - acetic acid 80:25:4 for (1) and (3). HPTLC-DPPH scavenging activity was determined by dipping into a methanolic DPPH solution, followed by drying for 90 s in the dark and heating at 60 °C for 30 s. The hRF values of dominant radical scavenging zones were in the range of 75-85 for (1), 70-90 for (2) and 64 and 95-100 or (3). HPTLC-antimicrobial Aliivibrio fischeri assay allowed the determination of major antimicrobial zones at hRF 40-49 and 55-66 or (1), 23, 45 and 60 for (3) and 95 for (2). Additional effect-directed analyses employing acetylcholinesterase (AChE) assay, planar yeast estrogen (pYES) bioassay and Bacillus subtilis bioassay as well as subsequent HPTLC-ESI-MS allowed targeted characterization of bioactive compounds.

Phytochem. Anal. 26, 97-104 (2015). HPTLC of gymnemagenin in the leaves of Gymnema sylvestre on silica gel with toluene - chloroform - methanol 5:8:3. Detection by spraying with vanillin-sulfuric acid reagent, followed by heating at 110 °C for 10 min. Quantitative determination by absorbance measurement at 610 nm. The hRF value of gymnemagenin was 46. Linearity was in the range of 400-3000 ng/zone. LOD and LOQ were 0.07 and 0.55 ng/zone, respectively. Intra-day and inter-day precisions were below 2 % (n=3). Average recovery was 93 %.

J. Planar Chromatogr. 28, 466-471 (2015). TLC of L-glutamic acid in a solution of Astragalus complanatus coarse powder on silica gel with n-butyl alcohol - glacial acetic acid - water 4:1:1. Detection by spraying with 0.2 % ninhydrin - acetone solution 10:1, followed by heating at 105 °C. Quantitative determination by measuring pixels after photographing. Linearity was in the range of 10-60 μg/zone. Average recovery was 103 %. Different measures to reduce the error were proposed.

J. Liq. Chromatogr. Relat. Technol. 38, 1794-1801 (2015). 2D-TLC of eleven essential oils from nine Mentha species on silica gel with ethyl acetate - toluene 5:19 in the first direction and ethyl acetate - n-heptane 3:17 in the second direction. Detection by dipping into p-anisaldehyde reagent (0.5 mL p-anisaldehyde solution in 50 mL glacial acetic acid and 1 mL concentrated sulfuric acid) followed by heating at 105 °C for 10 min. Evaluation under 254 nm. The developed plates were immersed in a 0.2 % methanolic solution of 2,2-diphenyl-1-picrylhydrazyl (DPPH radical reagent) and scanned after 30 min.

J. Liq. Chromatogr. Relat. Technol. 38, 1731-1739 (2015). HPTLC of asenapine maleate in pharmaceutical formulations on silica gel with methanol. Quantitative determination by absorbance measurement at 235 nm. The hRF value for asenapine was 43. Linearity was in the range of 300-1800 ng/zone. LOD and LOQ were 39 and 119 ng/zone, respectively. The intermediate precision was below 0.2 % (n=3). Recovery was in the range of 99-102 %. Results were comparable to those obtained by HPLC.