Improved structural annotation of triterpene metabolites of traditional Chinese medicine in vivo based on quantitative structure-retention relationships combined with characteristic ions: Alismatis Rhizoma as an example

•A strategy was proposed to annotate metabolites of traditional Chinese medicine.•The candidate structures of prototype compounds and metabolites were determined.•A QSRR model was established to predict the retention time of candidate structures.•61 unknown prototypes and in vivo metabolites of AR triterpenes were annotated.•Typical compound identified by this strategy was successfully validated using triterpene standard.