In
this work, a new mega-method of sample preparation called “QuEChERSER”
(more than QuEChERS) is being presented for the first time. Fast,
efficient, and cost-effective analysis of chemical contaminants in
meat is useful for international trade, domestic monitoring, risk
assessment, and other purposes. The goal of this study was to develop
and validate a simple high-throughput mega-method for residual analysis
of 161 pesticides, 63 veterinary drugs, 24 metabolites, and 14 legacy
environmental contaminants (polychlorinated biphenyls) in bovine muscle
for implementation in routine laboratory analyses. Sample preparation
of 2 g test portions entailed QuEChERS-based extraction with 10 mL
of 4:1 (v/v) acetonitrile/water, and then 204 μL was taken,
diluted, and ultracentrifuged prior to analysis of veterinary drugs
and pesticides by ultra-high-performance liquid chromatography−tandem
mass spectrometry. The remaining extract was salted out with 4:1 (w/w)
anhydrous MgSO4/NaCl, and 1 mL was transferred to an autosampler
vial for automated mini-cartridge solid-phase extraction (Instrument
Top Sample Preparation) cleanup with immediate injection using fast
low-pressure gas chromatography−tandem mass spectrometry analysis.
The automated cleanup and both instruments were all operated in parallel
in 13−15 min cycle times per sample. Method validation according
to United States Department of Agriculture requirements demonstrated
that 221 (85%) of the 259 analytes gave average recovery between 70
and 120% and interday relative standard deviation of ≤25%.
Analysis of a certified reference material for veterinary drugs in
freeze-dried bovine muscle was also very accurate, further demonstrating
that the QuEChERSER mega-method can be implemented to save time, labor,
and resources compared to current practices to use multiple methods
to cover the same analytical scope.
The goal of this study was to develop
and validate a new method
for simultaneous determination of 106 veterinary drugs and 227 pesticides
and their metabolites plus 16 polychlorinated biphenyls (PCBs) at
and below their regulatory levels established for catfish muscle in
the European Union and U.S.A. To do this, two different QuEChERS-based
methods for veterinary drugs and pesticides and PCBs were modified
and merged into a single mega-method dubbed “QuEChERSER”
(more than QuEChERS), which is presented here for the first time.
The mega-method was validated in catfish at four different spiking
levels with 10 replicates per level. Sample extraction of 2 g test
portions was made with 10 mL of 4:1 (v/v) acetonitrile/water, and
then an aliquot was taken for ultra-high-performance liquid chromatography–tandem
mass spectrometry (UHPLC–MS/MS) analysis of 106 veterinary
drugs and 125 pesticides, including metabolites. The remaining extract
after salting out was subjected to automated mini-solid-phase extraction
cleanup (Instrument Top Sample Preparation) for immediate injection
in low-pressure gas chromatography–tandem mass spectrometry
(LPGC–MS/MS). The cleanup was conducted in parallel with the
10 min LPGC–MS/MS analysis for 167 PCBs, pesticides, and metabolites,
which was conducted in parallel with the 10 min UHPLC–MS/MS
analysis for 231 analytes to increase sample throughput (49 analytes
were included in both techniques). In MS/MS, three ion transitions
were monitored for nearly all targeted analytes to provide unambiguous
identification as well as quantification. Satisfactory recoveries
(70–120%) and relative standard deviations of ≤20% were
achieved for 98 (92%) of the veterinary drugs and their metabolites
and for 222 (91%) of pesticides, metabolites, and PCBs, demonstrating
that the developed method is applicable for the analysis of these
contaminants in fish as part of regulatory monitoring programs and
other purposes.
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