J. AOAC Int. 90, 920-924 (2007) TLC of commercial products containing Aesculus hippocastanum, Turnera diffusa, Matricaria recutita, Passiflora incarnata, and Tilia occidentalis against standardized extracts on silica gel with ethyl acetate - formic acid - acetic acid - water 100:11:11:27 with chamber saturation. Detection by spraying with 1 % methanolic diphenylborinic acid 2-amino ethyl ester, followed by 5 % ethanolic polyethylenglycol 400 (PEG) and visualization under UV light at 365 nm or with anisaldehyde - sulfuric acid reagent followed by heating at 100 - 110°C and visualization under visible and UV light at 365 nm. The standards contained aescin, apigenin-7-glucoside, other glycoside flavonoids, flavonoid aglycones, quercetin, myricetin, kaempferol, and rutin.

J. Chromatogr. Sci. 46 (6), 565-573 (2008). Investigation of selected amino acid standards on cellulose layers using organic-aqueous eluent systems modified with neutral and chaotropic salts: chlorides, iodides, nitrates, thiocyanates, perchlorates, and hexafluorophosphates at low concentrations from 10 to 80 mM in the mobile phase. The effect of salts used as mobile phase modifiers was evaluated by comparison of densitograms, peak symmetry coefficients, and theoretical plate numbers. The efficiency of the investigated chromatographic systems depends primarily on the kind of salt and organic solvent in the mobile phase. The best efficiency was obtained by adding ammonium thiocyanate to the mobile phase which contained acetonitrile as an organic modifier.

Part II. Connection with RP18 and silica plates. J. Chromatogr. Sci. 46 (4), 291-297 (2008). Optimization of the one-dimensional TLC of alkaloid standards on cyano phase, RP-18W, and silica gel with various eluents containing silanol blockers (besides diluent and modifier), such as diethyl amine or ammonia. Separation of alkaloid mixtures with the most selective system (e.g. methanol - water 4:1 in the first direction and methanol - acetone - diisopropylether - diethylamine 15:15:69:1 in the second direction) with an adsorbent gradient method. Alkaloids or plant extracts of Chelidonium majus, Fumaria officinalis, or Glaucium flavum were chromatographed in the first system, the plates were connected with the plate pre-coated with various adsorbents, and partly separated fractions were transferred to the second layer and developed in a second system. Cyano - silica - RP-18W and cyano - silica - silica were used as the connected layers. The alkaloids were identified based on the Rf values of standards, and by comparison of UV spectra obtained by densitometry with a diode array detector.

J. Planar Chromatogr. 21, 119-123 (2008). TLC of aqueous Senna and Tilia extracts with sennoside A and B as standards on silica gel after immersion in acetonitrile - water 17:3, with 2-propanol - ethyl acetate - water 9:9:7 (for Senna extracts) and 2-butanone - ethyl acetate - formic acid - water 3:5:1:1. Detection under UV 254 nm. Although quantitative analysis was not performed, peak areas served for comparative evaluation.

Chromatographi 68 (1-2), 129-133 (2008). Description of a simple, rapid, specific and sensitive method for the quantitative estimation of mevalonic acid in leaves of Artemisia annua, Psorelia corylifolia, Vinca rosea, Withania somnifera and Barleria proinites. TLC of leaf extracts on silica gel with benzene - acetone 3:2 which involved conversion of mevalonic acid to its lactone, mevalonolactone. Detection by treatment with anisaldeyde reagent. Quantitative determination of mevalonolactone by absorbance measurement at 600 nm. Linearity was between 100 and 500 ng per spot. Recovery (by standard addition) was higher than 98 % for mevalonolactone. The limit of detection was 50 ng per spot.

J. Chromatogr. A 1216 (7) , 1035-1052 (2009). A review on two-dimensional TLC in the analysis of secondary plant metabolites. Plant extracts are usually very complex mixtures, therefore chromatographic methods are one of the most popular analysis techniques. The separation power of one-dimensional techniques is usually inadequate, therefore in this paper multidimensional planar chromatographic methods are reviewed. General aspects of multidimensionality are discussed. Attention is drawn to the potential of two-dimensional planar chromatography in the field of phytochemistry.

J. Liq. Chromatogr. Relat. Technol. 31, 819-827 (2008). TLC of MDMA (3,4-methylenedioxymethamphetamine, ,ecstasy’) and impurities on silica gel with chloroform - methanol - acetonitrile 5:2:3. Detection under UV 254 and 366 nm after drying the plates at 110 °C for 15 min.

J. AOAC Int. 91, 1203-1209 (2008). HPTLC of atrazine, clofentezine, chlorfenvinphos, hexaflumuron, terbuthylazine, lenacyl, neburon, bitertanol, and metamitron on silica gel with ethyl acetate - n-heptane 1:4, 3:7, 2:3, or 7:3 in a horizontal chamber. Detection by scanning in the range of 200 to 600 nm with a TLC-DAD scanner.