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.

growing in Nilgiri hills of India. J. Planar Chromatogr. 29, 347-355 (2016). HPTLC of forskolin in the roots of Coleus forskohlii on silica gel with toluene – ethyl acetate – methanol 180:60:1. Detection by dipping into anisaldehyde ‒ sulfuric acid reagent. Quantitative determination by absorbance measurement at 545 nm. The hRF value for forskolin was 48. Linearity was between 20 and 100 ng/zone. The intermediate precisions were below 1.6 % (n=3). The LOD and LOQ were 1 and 3 ng/zone, respectively. Recoveries were between 98.3 and 101.5 %.

Chinese J. of Inform. on TCM 21 (5), 95-97 (2014). Lianqiao Baidu Wan pill is a standard herbal TCM issued by the Ministry of Health, for treating swelling and pain, rheumatism, itching, constipation etc. For quality control, TLC on silica gel (1) for Ephedra sinica, with dichloromethane – methanol – ammonium hydroxide 20:7:1, detection by spraying with 0.1 % ninhydrin in acetone and heating at 105 ºC until the zones are clearly visualized, evaluation under white light; (2) for Radix sophorae flavescentis, with toluene – acetone – ethyl acetate – ammonium hydroxide 10:15:20:1, detection by spraying with 5 % potassium bismuthate solution and viewing under white light; (3) for Radix paeoniae rubra, with chloroform – ethyl acetate – methanol – formic acid 125:25:50:1, detection by spraying with 5 % vanillin in sulfuric acid – ethanol 1:4 and heating mildly until the zones are clearly visualized, viewing under white light.

Planta Medica 82(18), 1576-1583 (2016). The fractionation (by column and flash chromatography) of an aqueous extract of the aerial parts of Hilaria hirsuta was monitored through TLC on silica gel with n-butanol – acetic acid – water 13:3:5. The compounds (including flavonoids narcissin and rutin, and two new saponins, herniariasaponins G and H) were detected with anisaldehyde sulfuric acid reagent.

J. Food Comp. Anal. 61, 4-19 (2017). Review of the current methodologies available for determination of organosulfur compounds in garlic and other Allium species, including TLC and HPTLC for the analysis of alk(en)yl cysteine sulfoxides, S-allyl cysteine, thiosulfinates (mainly allicin), diallyl, mono-, di-, and tri-sulfides, vinyldithiins and (E)- and (Z)-ajoene.

Phytochem. Anal. 29, 5-15 (2018). TLC fingerprint of Ipomoea aquatica on silica gel with methanol – water from 1:1 to 9:1 (1) or methanol with 0.05 % trifluoroacetic acid – water with 0.05 % trifluoroacetic acid 1:1 (2). Detection by spraying with anisaldehyde sulfuric acid reagent. Detection under UV 254 nm, 366 nm, and for (2), white light (yellow bands at hRF 19 and 25). The post chromatographic visualization possibilities indicate the potential of TLC in qualitative fingerprint analysis.

J. Chromatogr. A 1482, 97-108 (2017). For the analysis of flavan-3-ols and proanthocyanidins in crude extracts of Japanese knotweed (Fallopia japonica Houtt.) rhizomes, the sensitivity of HPTLC-MS methods was improved by using two pre-developments of the silica gel layer, firstly with methanol – formic acid 10:1, and secondly with acetonitrile – methanol 2:1. HPTLC on silica gel and silica gel MS grade with toluene – acetone – formic acid 3:3:1; 6:6:1; 3:6:1, and dichloromethane – acetone – formic acid 10:10:1. Detection by derivatization with 4-dimethylaminocinnamaldehyde (DMACA) reagent and evaluation under white light allowed for the identification of flavan-3-ols and B-type proanthocyanidins from monomers up to decamers. Tentative identification of trimers, trimer gallates, tetramer gallates, pentamers, pentamer gallates, hexamers, hexamer gallates, heptamers, octamers, nonamers and decamers in Japanese knotweed rhizomes. Simultaneous identification of stilbenes (resveratrol, piceatannol hexoside, piceid) and anthraquinones (emodin, emodin-O-hexoside, emodin-O-(acetyl)-hexoside and emodin-O-(6′-O-malonyl)-hexoside).

J. Planar Chromatogr. 31, 169-172 (2018). HPTLC for the analysis of enzyme activity of the purified β-glucosidase from Cyamopsis tetragonoloba with natural isoflavonoid (genistin and daidzin) and flavonoid O-glycoside (rutin, naringin and hesperidin) substrates on silica gel with toluene – ethyl acetate – acetone – formic acid 20:4:2:1 for genistin, daidzin and rutin, methanol – chloroform 3:17 for hesperidin and methanol – ethyl acetate 3:7 for naringin. Detection under UV 254 nm. The hRF values were 18 and 32 for daidzein and genistein, respectively. TLC was successfully used as the first step for validation of the metabolic product formation.