Amantadine (MW 151.25) hydrochloride and acetaminophen are often added to cold medicine as main components. The protonated amantadine molecular ion and the fragment ions at m/z 152 and 135 can be observed in the full-scan mass spectrum (Supplementary Figure S-3h). The fragment ion at m/z 135 is consistent with that obtained by MPT-LTQ MS (Supplementary Figure S-1h). At the beginning of desorption and ionization, amantadine hydrochloride loses hydrochloric acid under the effect of microwave plasma. The fragment pathway of amantadine is relatively simple (Supplementary Figure S-2h). The peak at m/z 135 corresponds to the ion that formed by the loss of an ammonia molecule from protonated amantadine.