Fig. 4

UHPLC-DAD chromatograms of extracts from ATR and its adulterants. a UHPLC-DAD chromatograms of 16 samples (number 1–16 for different samples, shown in Table 1) at 270 nm were shown. Upper panel shows the markers, α-asarone and β-asarone. b Score plots for ATR and its adulterants, using peak areas of α-asarone and β-asarone as input data, were shown. c Hierarchical clustering analysis for the 16 samples. The loading plot was performed with the original peak areas of α-asarone and β-asarone as input data