Fig. 1

a Base peak chromatogram obtained by HPLC-ESI-Q-ToF of the DMSO extract of sample P.8 (“N^o 8 Laque Geranium 2 B. 131. N^o 816 III April 1926”). Peaks labelled with an asterisk are also present in the analytical blank; b isotopic cluster relative to the peak assigned to phloxine B (Acid Red 92) in the chromatogram (negative ionization); c tandem mass spectrum (30 V) of the parent ion at m/z = 784.5, showing the mass fragments assigned to phloxine B. The structure of the pigment in its phenolic form is provided in the inset