Negative ion mode DESI-MS spectra of PTFE leaf imprints. Spray solvent was 1% concentrated aqueous ammonia in methanol at a flow rate of 3 μL/min. (A) DESI-MS spectrum of a Katsura tree (C. japonicum) leaf imprint. (B, C) DESI-MS/MS spectra of the deprotonated molecules, m/z 643 and 627, corresponding to the two known chlorophyll catabolites in C. japonicum.7,45 Characteristic fragmentations due to the losses of methanol, and ring A are highlighted in the depicted structures. (D) DESI-MS spectrum of a hophornbeam (O. virginiana) leaf imprint. (E, F) DESI-MS/MS spectra of the deprotonated molecules, m/z 677 and 839, corresponding to the two chlorophyll catabolites found in O. virginiana. Characteristic fragmentations due to the losses of methanol, and ring A are highlighted in the inserted structures (proposed considering data for constitutionally identical compounds described in the literature3,48,57,58).