1056 Anal. Chem. 1987, 59. 1056-1059 be done selectively, and any ions that are not completely ejected can be removed by background subtraction. This is not true for electron impact excitation, since any ions trapped in the electron beam may undergo fragmentation, regardless of mass. Hence, electron impact excitation will require a more careful use of ion ejection for parent ion selection. For this reason, the use of a “notch ejection”(IO), or ...
