J. Planar Chromatogr. 26, 21-25 (2013). Online HPTLC of 2,2-Diphenyl-1-picrylhydrazyl (DPPH; 1) and ascorbic acid (2) on silica gel with methanol - water 17:3. Quantitative determination by absorbance measurement at 517 nm. The hRf values for (1) and (2) were 81 and 86, respectively. Linearity was in the range of 2-6 µg/zone for (1) and 1-5 µg/zone for (2). The LOD and LOQ were 3.9 and 13 ng for (1) and 4.5 and 15 ng for (2), respectively. The method allowed for estimation of reduction of DPPH by ascorbic acid. To investigate the applicability of the online reaction, in one set of experiments the reaction of DPPH and ascorbic acid was carried out in test tubes (external reaction), and in another set the reaction was carried out on TLC plates (online reaction) by spiking through application by overspraying of DPPH and ascorbic acid on the same track.

Food Chem. 210, 99-103 (2016). HPTLC of jasmonic acid in gamma-irradiated cabbage on silica gel with isopropanol – ammonia – water 10:1:1. Quantitative determination by absorbance measurement at 295 nm. The hRF values for jasmonic acid was 63. Linearity was in the range of 20-80 µg/zone. The LOD and LOQ were 6 µg/zone and 90 µg/zone, respectively. Recoveries were in the range 95.4-106.3 %.

J. Chromatogr. 347, 303-309 (1985). Study on HPTLC behaviour of phenylethylamines and phenolic acids on silanized silica impregnated with N-dodecylpyridinium chloride, or with dodecylbenzenesulfonic acid. The presence of KCl makes the spots more compact. The presence of 1 or more OH groups in the molecule decreases the retention of the compounds, whereas an opposite behaviour occurs with replacement of a phenolic group with an OCH3 group. Secondary amines are more strongly retained than primary amines. The N-CH3, groups increase the affinity of the compounds towards the exchanges in the order: primary amine secondary amine tertiary amine. Phenylethylamines, phenolic acids, silanized silica, ammonium tungstophosphate

J. Agric. Food Chem. 34, 633-638 (1986). Separation of -hydroxybutyric acid, succinic acid, beta-phenylacetic acid on silica with toluene - ethyl formate - formic acid 5:4:1. Detection by UV 254 nm. After extraction HPLC determination.

J. China Assoc. Inst. Anal. 6, 19-22 (1987) (Fenxi Ceshi Tongbao). TLC on silica with chloroform - methanol - acetic acid - water 80:10:8:2. Detection by exposing to iodine vapour. Quantification by densitometry at 520 nm.

Analyst 112, 1663-1665 (1987). TLC on silica with chloroform - methanol 85:15. Detection under UV 366 nm. Quantification by densitometry.

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.