Thin layer chromatography combined with electrospray ionization mass spectrometry for characterizing herbal compounds

Abstract

Characterizing the active ingredients and toxins in herbal products has important health implications in traditional Chinese medicine. Thin layer chromatography (TLC) is the most widely used technique for separating phytochemical compounds in plant extracts and has been coupled with mass spectrometry to provide sensitive and specific analysis. However, several analytical issues affect these methods, making them non-viable for long term and high-throughput analysis. We therefore developed a simple TLC/MS approach termed sawtooth thin layer chromatography-electrospray ionization/mass spectrometry (sawtooth TLC-ESI/MS) to directly scan and characterize herbal compounds on developed TLC plates that were modified into sawtooth pieces to facilitate rapid analysis. We directly induced electrospray ionization at each tip along the sawtooth edges to avoid detaching gel particles during analysis and to characterize both visualizable and non-visualizable analytes. Sawtooth TLC-ESI/MS was used to characterize the active ingredients and toxic compounds in Aconitum carmichaelii Debx and Panax ginseng root extracts. Sugar molecules and 16 alkaloids such as aconitine, mesaconitine, and hypaconitine were detected in the A. carmichaelii Debx extract, whereas 6 major ginsenosides were detected in the P. ginseng extract.