J. Planar Chromatogr. 2, 65-70 (1989). For qualitative analysis monodansyl cadaverine (MDC) was employed without further purification. Column-chromatographic purification is recommended for the quantification of short chain carboxylic acids. For in situ derivatization the carboxylic acid sample solutions were applied to the HPTLC plates as bands with a maximum length of 10 mm. These were then „overlayed“ with MDC solution containing N,N’-dicyclohexylcarbodiimide to activate the acids. Short-chain carboxylic acids were separated on normal silicagel phases with toluene - ethyl acetate - ammonia mixtures as mobile phase. Stepwise and gradient developments allow the baseline separation. Long-chain carboxylic acids are better separated on RP-18 phases with acetonitrile-tetrahydrofuran mixtures and methanol as mobile phase.

Chromatographia 32, 307-316 (1991). HPTLC on NH2-bonded silica with different solvent systems. Detection by heating at 150 °C. Quantification by densitometry in fluorescence mode at 366 nm. The detection limits in any case, below the physiological range.

Chromatographia 35, 627-630 (1993). TLC separation of free fatty acids into two fractions, a more mobile group of saturated and monounsaturated fatty acids and a less mobile group containing polyunsaturated fatty acids, on silica with hexane - acetic acid - water 50:2:1. Detection by exposure to iodine vapor, and under UV 254 nm. Determination of polyunsaturated fatty acids by HPLC.

by thin-layer chromatography.) (Chinese). Chinese J. Pharm. Anal. (Yaowu Fenxi Zazhi) 15, 30-32 (1995). TLC of ursolic acid on silica with toluene - ethyl acetate. acetic acid 60:25:3. Detection by spraying with 10% sulfuric acid in ethanol and heating at 105 °C for 5 min. Quantification by fluorodensitometry at 365 nm.

J. Chin. Trad. Med. (Zhongguo Zhongyao Zazhi) 20, 216-217 (1995). TLC on silica with chloroform - methanol - formic acid 40:1:1. Detection by spraying with 10 % sulfuric acid and heating at 90 °C for 10 min. Quantification by densitometry at 510 nm.

Acta Chromatographica 8, 5-12 (1998). HPTLC of EHMC on RP-18 with preadsorbent spotting area (prewashed with dichloromethane - methanol 1:1 and equilibrated with the mobile phase for 15 min) with methanol - tetrahydrofuran - deionized water 50:35:15. Detection under UV 254 nm. Quantitation by densitometry at 302 nm. Validation of accuracy, determination of precision. The relative standard deviation was 6.80% with a range 1.40 - 9.87% (n = 4). Average recoveries were 101.7 and 104.0%.

J. Planar Chromatogr. 13, 426-431 (2000). TLC of FAME (cis-7,10,13,16-docosatetraenoic acid methyl ester, cis-11,14-eicosadienoic acid methyl ester, cis-13,16,19-docosatrienoic acid methyl ester, nervonic acid methyl ester, cis-11,14,17-eicosatrienoic acid methyl ester, linoleic acid methyl ester, erucic acid methyl ester, oleic acid methyl ester, arachidic acid methyl ester, behenic acid methyl ester, stearic acid methyl ester, palmitic acid methyl ester) on silica gel. Plates were either impregnated by manual immersion or home-made plates were prepared from a suspension of silica gel in 10% aq. or ammoniacal AgNO3 solution. Chromatography was performed in horizontal chambers, with toluene - acetonitrile 97:3, petroleum ether - ether 1:1 and benzene - petroleum ether 1:1. For comparison TLC was also carried out on silica gel with chloroform - heptane 4:1, acetone - heptane 3:7, ethyl acetate-heptane 1:9, ethyl methyl ketone - heptane 1:4, tetrahydrofuran - heptane 1:9. Visualization under UV 366 nm after spraying with 0.1% Rhodamin B in methanol for argentated plates, or in visible light after exposure to iodine vapor and stabilization with starch solution, for silica plates.

J. Agric. Food Chem. 49, 4646-4655 (2001). TLC and preparative TLC of chlorogenic acid 3'-methyl ether [3-O-(3'-methylcaffeoyl)quinic acid] on silica gel and RP-18 with butanol - methanol - water 4:1:2 and methanol - water 3:7. Visualization under UV.