Representative HPLC–MS chromatograms of mixed standards and extract of Platycodi Radix in negative ion ESI mode. (A) mixed standards; (B) extract of Platycodi Radix; (C) selected ion monitoring of extract from Platycodi Radix. Selected ions as intact molecular ions of platycosides (m/z 1415, 1547, 1253, 1385, 1091, 1223, 1207, 1265, 1249) with the retention times of corresponding constituents presented in a chromatogram (C). The numbers indicate each platycoside in Fig. 1.