High-performance thin-layer chromatography and high-performance thin-layer chromatography–mass spectrometry methods for the analysis of phenolic acids

High-performance thin-layer chromatography (HPTLC) and HPTLC–mass spectrometry (MS)/(MSn) methods for analyses of phenolic acids (chlorogenic acid, rosmarinic acid, protocatechuic acid, gallic acid, syringic acid, ellagic acid, trans-cinnamic acid, o-coumaric acid, m-coumaric acid, p-coumaric acid, caffeic acid, ferulic acid, sinapic acid) were developed. Separation was performed on HPTLC silica gel plates with and without fluorescent indicator (F254) in a saturated twin-trough chamber using n-hexane–ethyl acetate–formic acid (12:8:2, v/v) as the developing solvent. The developed HPTLC method is also suitable for the preliminary screening of some flavonoids (flavone, apigenin, luteolin, chrysin, quercetin, myricetin, kaempferide, kaempferol, hesperetin, naringenin, pinocembrin), although some interferences of phenolic acids with flavonoids were observed. The effect of pre-development on the HPTLC analysis of phenolic acids on the detection by densitometry and mass spectrometry was also explored. Pre-devel...