Fig. 6

a Mass spectrum of alizarin (which exactly matches that of the isomeric compound 2,6-dihydroxyanthraquinone); b tandem mass spectrum (30 V) of the parent ion at m/z = 239.0 corresponding to 2,6-dihydroxyanthraquinone, along with its DAD spectrum; c tandem mass spectrum (30 V) of the parent ion at m/z = 239.0 corresponding to alizarin, along with its DAD spectrum. Spectra collected from the chromatogram of the extract of sample P.25, “Laque de Garance N^o 101”