Agriculture Reference
In-Depth Information
application of IT acquisition modes for screening (a single product ion) or con
rma-
tion (multiple product ions). They developed a screening method for nonpolar VDs
(
(five ionophores and two macrolides) in eggs. The proposed screening method was
validated by analysis of control, forti
ed, and incurred eggs (when the hens were
dosed with the parent drugs). In this way, it was able to screen and con
rm these
residues below 10
μ
g/kg (Table 6.3). Two years later,
the same authors [111]
developed a method for the screening and con
rmation of 29 polar VD residues
(sulfonamides,
MS
(employing two generations of ion trap instruments). This study was based on the
method described previously, employing a single product ion for screening and
multiple product ions for con
tetracyclines, and
fluoroquinolones)
in eggs by HPLC
-
IT
-
rmation purposes. LODs ranged from 10 to 50
μ
g/kg
(with LCQ Classic IT
MS)
(Table 6.3). The method was applied to the analysis of eggs from dosed hens, and the
ability to detect incurred residues was demonstrated. Smith et al. [59] also proposed
the use of LC
-
MS) and from 10 to 20
μ
g/kg (with Deca XP Plus
-
IT
-
-
IT
-
MS to screen and con
rm 38 compounds from a variety of VD
sh. MS
2
or MS
3
classes in four species of
spectra were monitored for each
compound, allowing screening and con
rmation simultaneously. The method was
able to con
rm all quinolones and
fluoroquinolones, macrolides, malachite green, and
most of the imidazoles at 0.01
μ
g/kg and
florfenicol amine, metronidazole, sulfona-
mides, tetracyclines, and most of the
β
-lactams at 0.1
μ
g/kg, while ivermectin and
penicillin G were detectable only at 1
ed samples (Table 6.3).
Additionally, the authors demonstrated that an easy modi
μ
g/kg in forti
cation of the method
could be used to analyze metabolites, detecting the presence of metabolite hydrox-
ymetronidazole and the metabolites of albendazole (sulfone, sulfoxide, and
aminosulfone).
The hybrid QLIT instrument has also been used for screening purposes using the
MS/MS mode. Hammel et al. [113] employed HPLC
MS/MS using SRM
mode to carry out a multiscreening of 42 VDs in honey (Table 6.3). The two most
intense fragment ions were selected for each compound, being the most intense SRM
used for quantitative analysis and the second SRM for analyte con
-
QLIT
-
rmation. This
proposed screening method utilized an internal limit at 20
g/kg, without specifying if
such limit can be considered as the cutoff concentration of the method. Finally, it was
validated and good performance data were obtained for 37 analytes out of the 42
studied.
μ
6.4.2 Confirmation and Quantification Methods
HRMS analyzers have also been applied for the quantitative analysis of VDs,
although they have not been easily accepted as quanti
cation tools due to the
predominance of QqQ or IT as the only analyzers capable of obtaining accurate
trace-level quanti
cations, as evidenced by the following quote:
“
Obviously, a
Q
TOF mass spectrometer instrument will most probably never take the place of
our trusted QqQ or IT instruments
-
[63]. However, numerous improvements in
HRMS techniques have increased selectivity, sensitivity, and dynamic range to be
adequate for quantitative purposes and some published work has demonstrated their
”
