Application of HPTLC-MS for the identification of flavonoids in herbal extracts

Only recently, a very convenient and universal HPTLC-MS Interface became available, which semi-automatically can extract zones of interest and direct them into a LC-MS system [1]. Substances are directly extracted from a TLC/HPTLC plate and mass spectra are obtained within a minute. So far, the method has hardly been applied for the analysis of plant extracts [2]. We now have tested the HPTLC-MS Interface for investigation of flavonoid containing herbal drugs. Extracts and pure compounds have been applied as bands onto HPTLC plates using an automatic TLC sampler. Chromatography was performed in an automatic developing chamber with humidity control. Separated zones were eluted from the plate with the TLC-MS Interface using acetonitrile as solvent delivered by an HPLC pump at 100µl/min. The interface was hyphenated to a Finnigan LCQ Deca XP Plus ion trap mass spectrometer equipped with an electro spray ionization (ESI) source. Rutoside, hyperoside, vitexin, quercetin and rosmarinic acid as pure substances were used to optimize extraction, detection and identification by HPTLC-MS. It was possible to identify hyperoside, vitexin, quercetin and rosmarinic acid also in an extract of Thymus vulgaris. Therefore, the HPTLC-MS interface proved to be a quick and powerful tool for the on-line identification of flavonoids in TLC separations. It can complement the classical TLC detection tools.

References: 1. Luftmann, H. et al. (2007) Rapid Commun Mass Spectrom 21: 3772–3776.

2. Reich E, Widmer V. (2009) Planta Med. 75(7):711–718.