An unexpected ion-molecule adduct in negative-ion collision-induced decomposition ion-trap mass spectra of halogenated benzoic acids.
The ion observed at m/z 145 when product ion spectra of iodobenzoate anions are recorded using ion-trap mass spectrometers corresponds to the adduct ion [I(H(2)O)](-). The elements of water required for the formation of this adduct do not originate from the precursor ion but from traces of moisture present in the helium buffer gas. A collision-induced decomposition (CID) spectrum recorded from the [M-H](-) ion (m/z 251) derived from 3-iodo[2,4,5,6-(2)H(4)]benzoic acid also showed an ion at m/z 145. This observation confirmed that the m/z 145 is not a product ion resulting from a direct neutral loss from the carboxylate anion. (79)Bromobenzoate anions produce similar results showing an ion at m/z 97 for [(79)Br(H(2)O)](-). The ion-molecule reaction observed here is unique to ion-trap mass spectrometers since a corresponding ion was not observed under our experimental conditions in spectra recorded with in-space tandem mass spectrometers such as triple quadrupole or quadrupole time-of-flight instruments.
Attygalle
Athula B
AB
Center for Mass Spectrometry, Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, NJ 07030, USA. athula.attygalle@stevens.edu
Kharbatia
Najeh
N
Bialecki
Jason
J
Ruzicka
Josef
J
Svatos
Ales
A
Stauber
Einar J
EJ