“…In the literature many coumarins in A. dahurica have been investigated by HPLC, HPLC‐NMR‐MS, and HPLC ESI‐MS (Kang et al ., ; Kang et al ., ; Zheng et al ., ; Park et al ., ; Zhang et al ., ). However, there is no report on the characterization of trace amounts of coumarins in A. dahurica by using off‐line 2D‐HPLC–ESI/MS n .…”