J. Planar Chromatogr. 20, 303-306 (2007). TLC of p-hydroxybenzoic acid, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, salicylic acid, butylated hydroxyanisol, and butylated hydroxytoluene on stannic silicate with n-hexane - ethyl methyl ketone - acetic acid 80:20:3. Quantitation by scanning densitometry at 270 nm. The limit of detection and quantitation for p-hydroxybenzoic acid was 0.05 and 0.51 µg/zone, respectively.

Dtsch. Apoth. Ztg. 127, 1867-1869 (1987). TLC of thiomersal, thiosalicylic acid, dithiosalicylic acid on silica with chloroform - methanol NH3 (25%) 60:30:10. Visualization with dithizon.

Chromatographia 45, 145-148 (1997). TLC on silica with butylacetate - formic acid - 2-propanol 5:2:3. Quantification by densitometry at 250 nm. Comparison with HPLC method. Detection limit ca. 25 ng for both methods.

Chromatographia 70 (7-8), 1277-1282 (2009). HPTLC of preservatives on three stationary phases of different polarity: RP-18, RP-18W and cyano phase, with methanol – water mixtures in different volume proportions. The resulting RM values showed a linear decrease with increasing methanol concentration of the mobile phase (determination coefficients for all stationary phases were >0.98). The retention behavior of the preservatives on RP phase is in good agreement with their polarity. Principal component analysis showed that for all three stationary phases the same lipophilic interactions take place.

J. Chromatogr. 437, 59-82 (1988). TLC of 54 amines on silica with benzene and benzene - ethyl acetate - acetone 100:5:1. Detection by spraying with N-chloro-2,6-dichloro-P-benzoquinone monoimine in buffered alkaline medium. Identification of several imprecisely defined products. Establishment of theoretical correlations between chemical structures, Rf values and colors of spots.

J. Planar Chromatogr. 10, 463-464 (1997). TLC on silica with hexane (12 cm), and, after drying - in the same direction - with petrol ether (10 cm). Detection by spraying with 20% ethanolic phosphomolybdic acid and heating at 105°C. Quantification by densitometry at 600 nm.

J. Planar Chromatogr. 23, 250-254 (2010). TLC of 30 food additives (aldehydes, organic acids, esters and alcohols, and various sodium salts) on titanium(IV)silicate ion-exchanger with 10 different mobile phases: e. g. methanol, heptane - diethylether 4:1, aqueous ammonia - methanol - ethyl acetate 1:3:6, methanol - aqueous ammonia 9:1, methanol - ethanol 17:3, 0.5 M ammonium sulfate solution, 0.25 M, 0.5 M and 0.1 M potassium bromide solution, and phosphate buffer pH 2.5 in a twin-trough chamber without chamber saturation. Detection by spraying with 1 % iron chloride solution, 0.5 % potassium permanganate and 3 % barium chloride solution 1:1, 1 % ninhydrin in ethanol, 2 % phosphomolybdic acid in ethanol, and 5 % potassium dichromate in concentrated sulfuric acid. The study shows that the quality of separation depends to a large extent on the mobile phase, and selectivity is achieved by varying the composition of the mobile phase.

Thin-layer chromatographic procedure for the identification of preservatives in cosmetic products. J. Chromatogr. 410, 395-411 (1987). TLC of 88 preservatives on silica and alumina with ethyl acetate - diisopropyl ether - 96% ethanol - 25% NH3 55:30:10:2. Detection under UV 254 nm and by spraying with six reagents. Investigation of the retention behavior and the detectability of the preservatives, of which 74 were characterized. Detection limit, in the concentration range of 0.1%.