Acta Chromatographica 21(1), (2009) . This study focused on the attempt to suppress the spontaneous oscillatory in-vitro chiral conversion of a-substituted propionic acids using, as example, L-lactic acid dissolved in water in the presence of copper(II) cations to check whether the coordinate covalent bonds between copper(II) and L-lactic acid ligands prevented the latter species from oscillatory chiral conversion. Aqueous solutions of copper(II) acetate and lactic acid in the molar ratios 1:1, 1:2, and 1:3 were stored and the possible chiral conversion of L-lactic acid was monitored by TLC, polarimetry, and circular dichroism spectroscopy. It was found that chelating of copper(II)cations with L-lactic acid did not result in suppression of the spontaneous oscillatory in-vitro chiral conversion of the acid from the TLC data. Different molar proportions of copper(II) cation and L-lactic acid had somewhat different effects on the dynamics of conversion, in contrast, when L-lactic acid is dissolved in water in the presence of copper(II)cations almost no chiral conversion is observed from polarimetric and circular dichroism studies. It was therefore concluded that chelating of copper(II) cations with L-lactic acid stabilizes the chiral structure of the acid in solution. The structure-stabilizing effect of copper(II) cations is weakened by the TLC system due to the interaction of the copper(II)-L-lactic acid complex with the silica gel.

J. of Chromatogr. A 1218 (24), 3811-3815 (2011). HPTLC of sugars in bio-oil fractions on silica gel with acetonitrile - water 4:1, or mixtures of butanol and formic acid, followed by detection with the aniline - diphenylamine - o-phosphoric acid reagent. The method allowed for the separation of the anhydrosugars levoglucosan and cellobiosan, as well as glucose, arabinose, xylose and cellobiose without the need of pre-treatment and pre-derivatization of samples. Volatile compounds present in bio-oil did not interfere with sugar analysis, and the detrimental effect of the complex bio-oil matrix on columns and detector lifetime is avoided by using disposable HPTLC plates. It was found that the concentrations of levoglucosan and cellobiosan in bio-oil samples obtained from Pinus radiata sawdust were ranged between 1.3-2.3 % and 1.0-2.0 % respectively, while a higher levoglucosan concentration was in a bio-oil sample obtained from native wood.

J. of Chromatogr. A 1218 (50), 9111-9114 (2011). A short communication on the fractionation, separation and identification of spinochrome pigments from sea urchin (Strongylocentrotus droebachiensis) shells by TLC with off-line HPLC coupled to diode array detection and microTOF-Q mass spectrometry (HPLC–DAD–MS). Two fractions of pigments were obtained and separated by TLC, then eluted with methanol directly into the MS using the TLC-MS Interface. The HPLC-DAD-MS analysis of the fractions indicated the presence of six sea urchin pigments: spinochrome monomers B and D, three spinochrome dimers (anhydroethylidene-6,6'-bis(2,3,7-trihydroxynaphthazarin) and its isomer and ethylidene-6,6'-bis(2,3,7-trihydroxynaphthazarin)), and one pigment that was preliminary identified as a spinochrome dimer with the structural formula C22H16O16.

Food Research International 44, 2258-2263 (2011). HPTLC of sugar constituents linked to anthocyanidin in the fruits of Acanthopanax sessiliflorum on silica gel with n-propanol - water - 30 % ammonia 20:5:1 + 1 drop triethylamine. Detection by spraying with a solution of 0.3 % N-(1-naphtyl)-ethylenediamine and 5 % sulfuric acid in methanol, followed by heating at 121 °C for 10 min. The acidic hydrolysate consisted of the two monosaccharides, glucose and xylose.

J. of Chromatogr. Sci. 49, 560-567 (2011). Evaluation of the fingerprinting efficiency of a novel two-dimensional analytical system composed of RP-TLC and RP-LC-MS. The efficiency of the system was compared with that of the one-dimensional system RP-TLC with MS detection. The test samples were phenolic acid extracts from Salvia lavandulifolia. Both systems can be applied to the fingerprint analysis of herbal extracts, but the two-dimensional system based on RP-TLC and RP-LC-MS can provide more abundant information.

J. Planar Chromatogr. 24, 48-52 (2011). HPTLC of hydroquinone on silica gel with chloroform - methanol 17:3 in a twin-trough chamber after saturation for 30 min at 25 °C. Quantitative determination by densitometry in absorbance mode at 289 nm. The hRf of hydroquinone was 51. Linearity was between 100 and 2500 ng/zone. Mean recovery was 99.2 %, with %RSD between 1.7-2.0 %. The intra-day precision (n = 3) as %RSD was 0.9-1.1 % and the inter-day precision 1.0-1.2 %. The LOD and LOQ was 39 and 116 ng/band, respectively.

J. of Integrated Modern Trad. Chinese & Western Med. 20(13), 1634-1636 (2011). TLC of the extracts of Yinlishuang lotion on silica gel 1) for Phellodendron with chloroform - methanol - ammonia 50:10:1, detection under UV 365 nm; 2) for radix Sophorae flavescentis, with toluene - acetone - methanol 8:3:1, detection by spraying with diluted potassium iodobismuthate; 3) for fructus Cnidii, with toluene - ethyl acetate - n-hexane 3:3:2, detection under UV 365 nm. Identification by comparison of the fingerprint with the standards of the individual drug components.

J. Sep. Sci. 36, 1-19 (2013) The application of TLC in the characterization of polysaccharides from medicinal plants and fungi were reviewed. Physicochemical and structural characterization as well as fingerprinting methods were also described.