Identification of phenolic compounds in Equisetum giganteum by LC-ESI-MS/MS and a new approach to total flavonoid quantification

► Twelve phenolic compounds were identified by LC-DAD and LC-ESI-MS/MS in E. giganteum. ► The acid hydrolysis of flavonoid glycosides was statistically optimized. ► A LC-UV method was validated for flavonoid aglycones determination. ► The method was suitable for the assay of flavonoid aglycones in Equisetum species.