B/E linked scan method

The B/E linked scan method may be applied with different ionization techniques, such as El, Cl, FD, SIMS, FAB, LDMS, under positive or negative mode [139], The success enjoyed by this type of technique is related above all to the large number of detection possibilities and to the reproducibility of spectra, due to the development of thermostatically controlled Hall probes. 

In order to increase the possibility of collisional activation, the current trend is to develop this mode (on universally accessible conventional geometry instruments), utilizing the detection of decomposition produced in the first FFR by the B/E linked scan method. Nevertheless, although the resolution of fragment ions is better in this mode, that of precursor ion resolution remains mediocre and does not lead to as good a separation of isobaric ions as in the case of MIKE mode. ... 

The situation is less complicated when MS/MS is used. It is occasionally possible, however, to perform isotopic assays on fragment ions, providing their mechanism of formation is known and one is sure that no specific exchange of H or D atoms occurs in the positions assayed. It is sufficient to know a fragment ion (no longer labeled) which is produced at least from the molecular ion. The search for these precursors with the HV scan and B /E linked scan methods leads to the direct determination of isotope distribution (sensitivity and reproducibility are good). 

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