J. Liq. Chromatogr. Relat. Technol. 42, 249-257 (2019). Review of HPTLC methods published after 2000 for the analysis of vegetables, including bioactive compounds such as indoles, glycolipids, carotenoids and anthocyanins. TLC methods for the identification and quantification of pesticide residues such as iprodione, vinclozolin, cymoxanil, deltamethrin and parathion were reviewed. TLC coupled with other non-chromatographic techniques for the analysis of inorganic species, mycotoxins, glycoalkaloids and polyamides was described.  

J. Liq. Chromatogr. Relat. Technol. 42, 274-281 (2019). HPTLC of caffeine in caffeine-containing botanicals and caffeinated products on silica gel with toluene - acetone - formic acid 9:9:2. Detection by dipping into NP reagent (1 g of diphenylborinic acid aminoethylester in 200 mL of ethyl acetate), followed by derivatization with anisaldehyde reagent, then heating at 100 ºC for 3 min. Quantitative determination by absorbance measurement at 273 nm. The hRF value of caffeine was 70. Linearity was between 30 and 120 ng/zone. The intra-day and inter-day precision was below 5 % (n=3). The LOD and LOQ were 10 and 30 ng/zone, respectively. Recovery rate was between 101 and 118 %.

J. Planar Chromatogr. 32, 191-196 (2019). HPTLC of phenolic compounds in 11 dark beers, 25 light beers, 10 non-alcoholic beers and 4 malt beers on silica gel with ethyl acetate - formic acid - acetic acid - water 50:55:55:13. Detection by dipping into a (1) 0.5 % methanolic solution of 2-aminoethyl diphenylborinate (natural product reagent or Neu’s reagent), followed by dipping into a 5 % methanolic polyethylene glycol (PEG) 400 solution for enhancement and stabilization of the fluorescent zones, or (2) 0.2 % methanolic DPPH radical solution. Documentation under white light and UV 366 nm. Zones at hRF values of 8, 13, 36, 45, 52 and 85 had the most impact on the principal component (PC) analysis and were recognized as markers for discrimination between dark and non-alcoholic beers. HPTLC-ESI-HRMS/MS² analysis allowed the identification of desdimethyl-octahydro-iso-cohumulone (hRF 85) and iso-n/ad-humulone (hRF 95) as the most active bands with radical scavenging property.

Food Chem. 91, 757-764 (2005). HPTLC of dihydrosanguinarine (1), after its conversion to sanguinarine (2) as an index of argemone oil adulteration in edible mustard oil, on silica gel with hexane – acetone – methanol 16:3:1. The plate was irradiated under long wave UV light for 15 min to oxidize (1) to (2). Quantitative determination by absorbance measurement at 366 nm. The hRf values for (1) and (2) were 82 and 36, respectively. Linearity was between 5 and 300 ng/zone for (2). The limit of detection and quantification was 1 and 3 ng/zone. Recovery was between 79 and 82 %.

J. Planar Chromatogr. 21, 89-96 (2008). TLC of dyes in normal-phase systems on silica gel, diol phase, cyano phase, and amino phase, and in reversed-phase systems on cyano phase, Diol phase, amino phase, and RP-18. RP chromatography with different mobile phase modifiers (THF, dioxan, methanol, acetonitrile, and acetone) at different concentrations, containing different amines, cationic and anionic ion-pair reagents, buffers, and ammonia, again at different concentrations. Based on the results the best system was selected: HPTLC of tartrazine, sunset yellow FCF, allura red AC, ponceau 4R, brilliant blue FCF, indigotine, brilliant black PN, quinoline yellow, patent blue V, brilliant green BS, azorubin, and brown HT on RP-18 with acetate buffer pH 3.5 containing 15-25 % modifier and 0.025 M propylamine or diethylamine. Detection in white light and under UV 254 and 366 nm. Quantitation by diode array densitometry in the range of 191 to 1033 nm.

J. Liq. Chromatogr. Relat. Technol. 30, 2941-2951 (2007). TLC of 6-gingerol and 6-shogaol in commercial Ginger on silica gel with n-hexane - diethyl ether 2:3. Detection by spraying with anisaldehyde - sulfuric acid reagent. Evaluation under white light and quantitative determination by absorbance measurement at 577 nm.

Part I: Graft TLC of selected coumarins. J. Planar Chromatogr. 21, 237-241 (2008). HPTLC of coumarins (present in extracts of Archangelica officinalis, Pastinaca sativa and Heracleum sphondylium fruits) on cyano phase with acetonitrile - water 3:7 (triple development) in the first dimension, and on silica gel with ethyl acetate - n-heptane 7:13 (triple development) in the second dimension. Good selectivity differences were also obtained on silica gel with ethyl acetate - n-heptane 7:13 (triple development) in the first dimension and on RP-18 phase with methanol - water 11:9 (triple development) in the second dimension. Detection and quantitative determination by fluorescence measurement at 366 nm.

CBS Publishers & Distributors Pvt Ltd, New Dehli, 2010. Short review on planar chromatography in food analysis. Certain well-known applications are mentioned but important publications and recent scientific data is lacking.