J. Planar Chromatogr. 18, 290-293 (2005). TLC of gallic acid in tea extracts (gallic acid, caffeine, (+)-catechin, and tannic acid as standards) on silica gel in an unsaturated chamber with chloroform - ethyl acetate - formic acid 5:4:1. Densitometric measurement at 289 nm. Limit of detection 0.1 µg per spot.

J. Planar Chromatogr. 19, 449-453 (2006). HPTLC of caffeic, p-coumaric, and ferulic acid on silica gel with dichloromethane - acetonitrile - 90 % formic acid 95:5:1. Quantitative determination by absorbance measurement at 320 nm. The method is precise and accurate.

J. Planar Chromatogr. 20, 57-60 (2007). TLC of 5-methylcytosine, tryptamine, melatonin, tryptophan, indole-3-acetic acid, and indole on silica gel with 1-butanol - glacial acetic acid - water 12:3:5 and isopropanol - 25 % ammonia - water 8:1:1. Densitometry at 280 nm.

J. Chromatogr. A 1188 (2), 295-300 (2008). Determination of food dyes (tartrazine, azorubine and sunset yellow) in different products by HPTLC combined with image processing of scanned chromatograms, on 3-aminopropyl modified silica gel with isopropanol - diethyl ether - ammonia 2:2:1. Quantification by using digital processing of images with special-purpose software. The limit of detection was between 5 and 9 ng/spot and the limit of quantification was between 10 and 18 ng/spot. Recovery was between 96.4 and 102.7 %.

J. Food Comp. Anal. 21, 577-581 (2008). HPTLC of a novel fluorescent compound of nutmeg (Myristica fragrance) on silica gel with hexane – diethyl eter – acetic acid 50:50:1. Detection under UV at 265 nm or by spraying with sulphuric acid 50% followed by heating at 180 °C. The major fluorescent band at hRf 63 was further purified on silica gel using dioxane – acetonitrile – acetic acid 70:30:1. The hRf value of the novel compound was 61. Quantitative determination by absorbance measurement at 376 nm. Linearity was between 1 to 50 µg/spot. The compound was identified as 2-methyl-1,4,4a,8a-tetrahydro-endo-1,4-methanonaphthalene-5,8-dione.

J. Planar Chromatogr. 22, 59-63 (2009). HPTLC of paraquat, diquat, difenzoquat, mepiquat, and chloromequat on LiChrospher silica gel with 1-propanol - methanol - 2.5 M aqueous sodium chloride 1:1:3. Detection by immersion for 2 s in a solution of 50 mg sodium tetraphenyl borate in 50 mL of water containing 50 µL concentrated hydrochloric acid. The wet plate was illuminated for 5 min with UV light at 254 nm which resulted in the formation of fluorescing spots corresponding to mepiquat, chloromequat, and difenzoquat. Immediately after illuminating at 254 nm all spots were illuminated for 10 min with UV light at 365 nm, which converted all compounds into fluorescent derivatives. Then the dry plate was dipped into ethylene glycol - methanol 1:1 for 2 s, which enhanced the fluorescence by a factor of two. Detection by fluorescence measurement and averaged densitograms were obtained in the emission wavelength range from 440 to 480 nm.

J. AOAC Int. 92, 745-756 (2009). HPTLC of 25 dyes (brilliant black BN, tartrazine, ponceau 6 R, resorcin yellow, fast yellow AB, orcein, allura red, green S, amaranth, quinoline yellow, acid blue, erythrosine, sunset yellow FCF, indigo carmine, ponceau 4R, azorubine, brilliant blue FCF, carmine, scarlet GN, copper chlorophyll, enocyanine, chlorophyllin trisodium copper salt, curcumin, riboflavin-5-phosphate, riboflavin) on silica gel in a horizontal developing chamber with ethyl acetate - methanol - water - acetic acid 65:23:11:1 for 40 samples in 12 min. Relative humidity was 21 +/- 3 % at a temperature of 20 +/- 3 °C. Alternatively, a twin trough chamber or automatic developing chamber can be used. Quantitative determination by absorbance measurement at 11 different wavelengths. Repeatabilities (%RSD, n = 4) near the limit of quantification showed precisions of mostly <2.7 %, ranging between 0.2 and 5.2 %. Correlation coefficients (R >0.9987) and RSD values (<4.2 %) of the calibration curves were highly satisfactory using classical quantification. However, digital evaluation of the plate image was also used for quantification, which resulted in RSD values of the calibration curves of mostly <3.0%, except for two <6.0%. The method was applied for the analysis of some energy drinks and bakery ink formulations, directly applied after dilution. By recording of absorbance spectra in the visible range, the identities of the dyes found in the samples were ascertained by comparison with the respective standard bands (correlation coefficients >0.9996). If necessary for confirmation, online mass spectra were recorded within a minute.

J. Liq. Chromatogr. Relat. Technol. 33, 903-921 (2010). A variety of TLC-plates impregnated with oils (paraffin, olive, sunflower, corn, castor, cod liver) and fats (margarine butter, pig, sheep, pullet, human) were indirectly evaluated regarding lipophilicity by employing a series of experimental parameters estimated for a representative group of natural sweeteners from retention data. TLC of 13 sugars on oil- and fat-impregnated silica gel layers using five organic solvents as organic modifiers. Best results were obtained with mixtures of acetonitrile and water with chamber saturation for 10 min. Detection of the sugars by treatment with silver nitrate and sodium hydroxide followed by heating at 105 °C for 5 min.