DETERMINATION OF COLLISION-INDUCED DISSOCIATION MECHANISMS AND CROSS-SECTIONS IN ORGANOPHOSPHORUS COMPOUNDS BY ATMOSPHERIC-PRESSURE IONIZATION TANDEM MASS-SPECTROMETRY
Cs. Harden et al., DETERMINATION OF COLLISION-INDUCED DISSOCIATION MECHANISMS AND CROSS-SECTIONS IN ORGANOPHOSPHORUS COMPOUNDS BY ATMOSPHERIC-PRESSURE IONIZATION TANDEM MASS-SPECTROMETRY, Organic mass spectrometry, 28(5), 1993, pp. 585-592
Nineteen organophosphorus compounds (OPCs) of the generic classes (dia
lkyl alkyl'-phosphonates (twelve compounds) and tri-alkyl phosphates (
seven compounds) were investigated by atmospheric pressure ionization
(API) tandem mass spectrometry (MS/MS). All OPCs showed consistent and
comparable collision-induced dissociation (CID) pathways allowing for
a generalized scheme for dissociation. When the alkyl groups are equa
l to or larger than ethyl, CID mechanisms are dominated by McLafferty
rearrangements and neutral losses are stable molecules in all cases ex
cept cleavage of P-C or O-C bonds to form alkyl fragment ions. CID cro
ss-sections for the OPCs were determined with excellent reproducibilit
y and a good correlation was found with a simple model. Inferences wit
h respect to ionic structures were made from observed trends in the cr
oss-section measurements. Limitations in API-MS/MS instruments of this
design are found in the energy distribution of the ionization and ion
sampling events.