Agriculture Reference
In-Depth Information
334.1562), a known metabolite that
results from the loss of ethylene from
enro
oxacin.
Even though the application of TOF
MS analyzers was suc-
cessful for the screening of VDs in food samples, the requirement of high resolution
for the correct assignment of analyte masses in complex samples becomes a key factor
when these methods are applied. In consequence, after the successful applications of
other HRMS, such as single-stage Orbitrap
-
MS and QqTOF
-
-
MS or LTQ
-
Orbitrap
-
MS in biological
matrices [106,107], they were applied in food safety applications.
One of these
first studies evaluated the mass resolution required for trace analysis
in different food commodities. Kellmann et al. [103] evaluated the resolution power
for the screening and quanti
cation of 151 pesticides, VDs, mycotoxins, and plant
toxins using UHPLC coupled with single-stage Orbitrap
25min. In this
work, the authors evaluated the application of the full scan mass spectrometry for
generic screening assays and showed the importance of the resolving power require-
ments for accurate mass measurements. Analyses were performed with resolving
power settings varying from 10,000 to 100,000 FWHM in two different matrices:
honey as a representative matrix of intermediate complexity, and horse feed as a
realistic worst-case sample of high complexity. The results showed that 50,000
FWHM or higher were suggested for low concentrations of analytes in complex
matrices such as animal feed, whereas a resolving power of 25,000 FWHM was
sufficient for less complex matrices such as honey. Additionally, the authors high-
lighted that although a maximum resolving power can provide the best qualitative and
quantitative performance (Table 6.2), the use of the minimum-required resolving
power allows the use of faster scan rates (better compatibility with fast LC separation).
More recently, new approaches for Orbitrap
-
MS in
<
MS have been reported for the
screening of target VD residues, such as the development of a screening method
for the detection of 63 VDs in muscle tissues using UHPLC
-
-
LTQ
-
Orbitrap
-
MS [68].
Target compounds were identi
ed by their accurate masses and LC retention time,
employing a narrow mass window of 5 ppm and a resolving power of 60,000 FWHM
(Table 6.2). This screening method was also applied to the identi
cation of nontarget
compounds. For instance, apart from sulfadimethoxine,
N
-4-acetyl-sulfadimethoxine
is another of its metabolites, which was identi
ed in beef muscle. It was further
con
rmed by acquisition of product ions with CID fragmentation experiments, and by
comparison with a chemical standard. Despite the fact that MRLs are only set for the
parent compound and metabolites are not considered, this type of
finding can be
interesting for the improvement of MRLs and tolerance de
nitions. It has been
reported that in many cases, metabolites or transformation products of the parent
compound can be more toxic than the original drug [108].
Another report detailed the development of a screening method for the detection of
29 VDs in milk- and powdered milk-based formula samples by UHPLC coupled with
single-stage Orbitrap
4min) was used and the
samples could be tested regarding the presence or absence of the compounds below
the established cutoff values of
-
MS [64]. A rapid screening method (
<
g/kg for the majority of the studied compounds
(Table 6.2). The cutoff values were evaluated as the concentration at which the
sensitivity rate is 95%, when the
5
μ
<
β
-type error has been set at 5%. For nonnegative
