Bruker Daltonik GmbH
Instrument Layout
3.1.5 TOF/TOF Analyzer
The peculiarity of the ultraflex III analyzer is the LIFT device located in the flight tube,
which allows acquiring a full fragment ion spectrum with one single scan.
3.1.5.1 Precursor Ion Selector
The precursor ion selector (PCIS) as shown in Figure 3-6 works like a mass filter to
separate a particular parent ion and related fragments from all the other ions for
MS/MS analysis.
It consists of deflector plates arranged in vertical layers below each other. Consecutive
electrodes are coupled to a high voltage supply with alternating polarity, according to
the Bradbury-Nielsen principle. The potential difference between the plates generates
an electrostatic field perpendicular to the ion flight direction. This field deflects all the
ions entering this electrode arrangement.
Although the plates are coupled to the supply voltage due to the Bradbury-Nielsen
principle the ion selector is operated as an improved Barowsky precursor ion selector
to take advantage of this selection mode. Just in the moment when the selected ions
enter the deflection field the deflection is switched off. The potential between the
plates is kept to zero until the ions leave the deflector. In this moment the deflection is
switched on again, however with the reverse polarity. This mode results in a
compensation of the partial deflection, which occurs in the stray areas at both front
ends of the electrodes. This technique allows applying extraordinary short selection
times, which contributes to improve resolving power.
The
ultraflex III
is equipped with a second deflection unit
PLMS
(Post Lift Metastable
Suppressor) located between LIFT and the reflector. This assembly can be used to
remove daughter ions that are formed after the LIFT procedure by deflecting the parent
ion. Now only the fragments formed between the source and the LIFT continue their
journey to the reflector where they are separated by mass.
ultraflex III User Manual, Version 1.0
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