Département de chimie moléculaire

Collision induced dissocn. tandem mass spectrometry expts. were performed to unequivocally sep. compds. from an isobaric mixt. of two products. The Survival Yield curve was obtained and is shown to consist in a linear combination of the curves corresponding to the two components sep. For such a mixt., a plateau appears on the diagram in lieu of the continuous decrease expected allowing for the structural study of the two components sep. The width of the plateau critically relates to the fragmentation parameters of the two mol. ions, which need to be sufficiently different structurally for the plateau to be obsd. However, at const. fragmentation parameters, the authors obsd. the width significantly increases at large m/z. This makes the sepn. more and more efficient as isobars have larger m/z and the technique complementary to those applicable at low m/z only. The vertical position of the plateau relates linearly to the relative concn. of the two compds. that may be useful for quantification. Repeatability was estd. at 2{%} on a quadrupole ion trap. An advantage of using survival yield curves only, is that a priori knowledge of the resp. fragmentation patterns of the two isobars becomes unnecessary. Consequently, similar performances were obtained if fragments are isobaric, which is also demonstrated in the authors' study. The crit. case of reverse peptides, at low m/z and similar fragmentation parameters, is also presented as a limitation of the method. [on SciFinder(R)]