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Optimization of QuEChERS procedure coupled to GC-ECD for organochlorine pesticide determination in carrot samples
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Advisor(s)
Abstract(s)
An optimised version of the Quick, Easy, Cheap,
Effective, Rugged and Safe (QuEChERS) method for simultaneous
determination of 14 organochlorine pesticides in carrots
was developed using gas chromatography coupled with
electron-capture detector (GC-ECD) and confirmation by gas
chromatography tandem mass spectrometry (GC-MS/MS). A
citrate-buffered version of QuEChERS was applied for the
extraction of the organochlorine pesticides, and for the extract
clean-up, primary secondary amine, octadecyl-bonded silica
(C18), magnesium sulphate (MgSO4) and graphitized carbon
black were used as sorbents. The GC-ECD determination of
the target compounds was achieved in less than 20 min. The
limits of detection were below the EUmaximum residue limits
(MRLs) for carrots, 10–50 μg kg−1, while the limit of quantification
did exceed 10 μg kg−1 for hexachlorobenzene (HCB).
The introduction of a sonication step was shown to improve
the recoveries. The overall average recoveries in carrots, at the
four tested levels (60, 80, 100 and 140 μg kg−1), ranged from
66 to 111% with relative standard deviations in the range of 2–
15 % (n03) for all analytes, with the exception of HCB. The
method has been applied to the analysis of 21 carrot samples
from different Portuguese regions, and β-HCH was the
pesticide most frequently found, with concentrations oscillating
between less than the limit of quantification to
14.6 μg kg−1. Only one sample had a pesticide residue
(β-HCH) above the MRL, 14.6 μg kg−1. This methodology
combines the advantages of both QuEChERS and
GC-ECD, producing a very rapid, sensitive and reliable
procedure which can be applied in routine analytical
laboratories.
Description
Keywords
QuEChERS Carrots Organochlorine pesticides GC-ECD Tandem mass spectrometry
