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Effect of method of ion preparation on low‐energy collision‐induced dissociation mass spectra
Author(s) -
Nacson Sabatino,
Harrison Alex. G.,
Davidson William R.
Publication year - 1986
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210210604
Subject(s) - protonation , chemistry , dissociation (chemistry) , fragmentation (computing) , proton affinity , mass spectrum , acetic acid , collision induced dissociation , medicinal chemistry , ion , photochemistry , analytical chemistry (journal) , mass spectrometry , organic chemistry , tandem mass spectrometry , chromatography , computer science , operating system
The collision‐induced dissociation (CID) mass spectra of protonated cocaine and protonated heroin have been measured using a triple quadrupole mass spectrometer at 50 eV ion/neutral collision energy for protonated molecules prepared by different protonating agents. The CID mass spectra of protonated cocaine using H + (H 2 O) n , H + (NH 3 ) n and H + ((CH 3 ) 2 NH) n as protonating agents are essentially identical and it is concluded that, regardless of the initial site of protonation, the fragmentation reactions occurring on collisional activation are identical. By contrast, protonated heorin prepared with H + (H 2 O) n and H + (NH 3 ) n as protonating agents show substantial differences. That formed by reaction of H + (H 2 O) n shows a much more abundant peak corresponding to loss of CH 3 CO 2 H. From a comparison with model compounds, and from a consideration of the three‐dimensional structure of heroin, it is concluded that with H + (H 2 O) n as protonating agent significant protonation occurs at the acetate group attached to the alicyclic ring, leading to acetic acid loss on collisional activation, but that reaction of H + (NH 3 ) n leads to protonation at the nitrogen function. The proton attached to nitrogen cannot interact with the acetate group and, consequently, the probability of loss of acetic acid on collislional activation is greatly reduced.