(Layer impregnated with ammonium molybdate for TLC of water contaminated with phenols.) Z. Wasser-Abwasser-Forsch. 23, 113-115 (1990). TLC of phenols on silica impregnated with 5% ammonium molybdate using toluene-acetone-chloroform 49:35:25 as mobile phase. Detection limit for qualitative determination 0.6-1 µg per spot and for semiquantitative determinations between 2 and 10 µg.

J. China Assoc. Instr. Anal. (Fenxi Ceshi Tongbao) 11, 78-81 (1992). Description of the use of aqueous solutions of ß-cyclodextrin as the mobile phase in TLC of pyrocatechol, resorcinol and paradioxybenzene on polyamide. Investigation of the effect of temperature, concentration of ß-cyclodextrin and organic modifiers in mobile phase on the retention of the solutes.

Chromatographia 39, 564-568 (1994). Reversed-phase TLC of phenol mixtures on RP-8 and RP-18 silica with 1) chloroform - isopropanol 98:3, 2) benzene - methanol 8:1, 3) benzene - isopropanol 50:4, 4) methanol - water 2:1, and methanol - 0.2 M NaOH 2:1. Determination of the relationship between RM values and the composition of the mobile phase. Demonstration of the effect of hydrophobicity and the chemical structure of the phenols and their retention times.

J. Agric. Food Chem. 45, 1229-1233 (1997). HPTLC of pentachlorophenol on silica with toluene. Detection after nitric acid-mediated oxidation of PCB to tetrachloro-1,4-benzoquinone by spraying with 2.5 g tetramethyl-p-diaminodiphenylmethane containing 10 g citric acid in 500 mL of distilled water followed by heating at 100°C for 5 min. Detection limit 1 ppm/100 mg of wood.

J. Planar Chromatogr. 11, 330-335 (1998). HPTLC of phenol and 10 derivatives (included in the list of priority pollutants of the US EPA) on silica gel and polyamide. Analytes were separated in horizontal (DS) and vertical (AMD) chromatographic chambers. The best separation was obtained by isocratic elution with chloroform - dichloromethane - hexane - ethyl acetate 10:10:12:1 in a saturated, vertical chamber. In situ quantitation was performed by absorption UV or VIS light measurements. VIS absorption measurements were performed after developing the color reaction with W¸rsters salts (N,N,N,N-tetramethyl-1,4-phenylenediamine).

Planta med. 66, 396-398 (2000). TLC of curcumin, demethoxycurcumin, bis-demethoxycurcumin on phosphate impregnated silica gel (by immersion in a 5% aqueous solution of sodium dihydrogen phosphate, drying, and activation at 110°C for 15 min). Details of a separation on a gram scale see S.W. Pelletier et al., J. Nat. Prod. 49, 982-900 (1986), and J.C. Coll, B.F. Bowded, J. Nat. Prod. 49, 934-936 (1986).

(Laminaceae) leaves. J. Planar Chromatogr. 17, 18-21 (2004). TLC of polyphenols and rosmarinic acid on silica gel with 1) toluene - methyl acetate - formic acid 5:4:1; 2) ethyl acetate - methanol - water 77:13:10; 3) ethyl acetate - diethyl ether 8:2. Detection a) at 254 nm, b) in fluorescence after spraying with Neu-PEG reagent, and c) in visible light after spraying with 10 % iron(III) chloride solution. Quantitative determination by densitometry at 254 nm and spectra recording from 200 to 500 nm for identification.

Retention Behaviour on Polar Adsorbents (Silica gel, Aluminia, Polyamide) with Non-Aqueous Mobile Phase. Acta Chromatographica 9, 38-54 (1999). TLC of salicylic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, gentisic acid, protocatechuic acid, alpha-resorcylic acid, beta-resorcylic acid, gamma-resorcylic acid, gallic acid, vanillic acid, syringic acid, 3,5-dimethoxybenzoic acid, homoprotocatechuic acid, homogentisic acid, 4-coumaric acid, 2-coumaric acid, 3-coumaric acid, caffeic acid, ferulic acid, 3,4-dimethoxycinnamic acid, 2,5-dimethoxycinnamic acid, phloretic acid, hydrocaffeic acid, cinnamic acid on silica gel, alumina and polyamide layers with non-aqueous ternary mobile phases comprising a non-polar diluent (n-heptane), a polar modifier (2-propanol, dioxane, tetrahydrofuran or ethyl acetate) and 2 % glacial acetic acid to suppress the ionization of the solutes after preconditioning for 15 min in the mobile phase vapor. Detection at UV 254 nm and after derivatization by spraying with diazotized sulphanilic acid in 10 % sodium bicarbonate solution, or with a 2 % solution of iron chloride. The separation selectivity for benzoic acid derivatives was best on alumina for all the mobile phases investigated, especially for hydroxy derivatives. When methoxy derivatives of benzoic acid or cinnamic acid derivatives are separated the best selectivity was usually obtained on polyamide layers.