Agriculture Reference
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operated at 12,000 FWHM) versus a unit mass resolution-based MS/MS (QqQ
technology) detection was compared. The comparison covered a limited set of 36
analyte residues present at trace concentrations in honey. Complete validation was
performed for the honey matrix on single-stage Orbitrap
-
MS operated at 50,000
FWHM, TOF
MS/MS. Low recoveries at high-spiked concentrations
could be observed for several compounds when they were monitored by TOF
-
MS, and QqQ
-
-
MS.
In addition,
the low recovery rate was indicated by a poor determination
coef
cient covering the two orders of magnitude dynamic range (corresponding to
10
g/kg). This phenomenon was attributed to the saturation of the TDC
detector used in the TOF
-
1000
μ
MS instrument, which limits the dynamic range, as was
previously explained (Section 6.3.2.1). Furthermore, in many cases, recovery appar-
ently increased at the lowest concentration with TOF
-
MS and to a lesser degree with
MS/MS. Most of these cases could be explained by the increasing relative importance
of coeluting endogenous and exogenous compounds appearing at the same accurate
mass MS/MS trace. However, single-stage Orbitrap
-
MS analyzer did not show this
behavior at 50,000 FWHM. On the other hand, the results showed that determination
coef
-
cients and relative standard deviation (RSD) values were poorest for the utilized
12,000 FWHM TOF
-
MS instrument, whereas performance was slightly better using
single-stage Orbitrap
MS instead of MS/MS instruments. As a result, the authors
concluded that an equal or even a slightly better quantitative performance was
observed for the single-stage Orbitrap-MS-based approach referring to precision,
trueness, and dynamic range. A direct comparison of the sensitivity was not possible
because the sensitivity of MS/MS strongly depends on the number of transitions to
be monitored and in this work only 36 analytes were studied. Hence, although the
sensitivity was higher for unit mass resolution MS/MS, it is not true when a large
number of analytes have to be detected and quanti
-
ed.
rmatory capabilities of HRMS versus MS/MS were also
compared [117]. This included the critical evaluation of precision and accuracy of ion
ratios obtained by the use of MS/MS collision chambers, which includes precursor
selection versus nonprecursor-selected fragmentation as obtained by HRMS technol-
ogy. Two different nonprecursor-selected fragmentation techniques, as provided by the
single-stageOrbitrap
Additionally, the con
MS instrument, were evaluated: fragmentation in the electrospray
ionization (ESI) interface and fragmentation in the higher collision-induced dissociation
cell (HCD). It was observed that many ESI-fragmented compounds produced ion ratios
where the second ion was hardly visible and such ratios provided poor diagnostic
information, while the ratios obtained by ions produced in HCD were higher, and most
compounds showed acceptable ion ratios. Hence, the precision of fragmentations in
single-stage Orbitrap
-
cantly better than those in the ESI
interface. HCD even appeared to produce better ion ratio precision than a classical
collision chamber of anMS/MS instrument. However, poorer accuracy (forti
-
MS with HCD was signi
edmatrix
extracts versus pure standard solution) of ion ratios was observed when comparing data
obtained by Orbitrap
MS versus MS/MS. Additionally, the observed higher absolute
ion ratio deviations demonstrated that fragmentation ratios based on nonprecursor-
selected experiments (Orbitrap utilizing ESI or HCD fragmentations) seemed to be
affected to a certain degree by matrix effects.
-
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