Agriculture Reference
In-Depth Information
Figure 6.1.
Example of use of the high resolving power of single-stage Orbitrap for the determination of
norfloxacin and its isobaric interference.
Source
: Ref. [90], Figure 3, p. 1239. Reproduced with permission
of Springer.
IT analyzers consist of a metal ring electrode between two hyperbolic end-cap
electrodes to form a three-dimensional ion trap. The oscillating potential difference
established between the ring and end-cap electrodes creates a
field to store or pass ions
in and out of the traps. The trapped ions precess in the trapping
field with a frequency
that is dependent on their
m
/
z
. The IT mass analyzer allows working in multiple stage
mass fragmentation (MS
n
) mode and product ion scan MS/MS [88] mode, obtaining
good quality full scan spectra with relatively low amounts of analyte. It is the so-called
tandem-in-time MS. Only a limited number of ions can be monitored simultaneously
due to the occurrence of space charge effects and ion
-
molecule reactions, which
negatively affect sensitivity [91].
These drawbacks were overcome by LITs, which are also known as 2D ion traps.
They consist of a mass analyzer based on a four-rod quadrupole and end electrodes
that con
ne ions radially by a two-dimensional quadrupole ion trap [92]. The
advantages of a LIT versus a 3D IT include enhanced ion trapping capacity and
reduced space charge effects due to increased ion storage volume. More ions can be
introduced into the LIT, resulting in increased sensitivity and a larger dynamic range
compared with a 3D ion trap [79].
Signi
cant improvements in LIT technology have been achieved by the implemen-
tation of the hybrid QqQLIT platform where two quadrupoles precede a LIT mass
