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Abstract
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In this work, a novel layered sorbent for microextraction by packed
sorbent (MEPS) was introduced, which has been prepared by coating
graphene oxide/polyamide (GO/PA) nanocomposite (NC) onto
cellulose paper through solvent exchange method. Scanning electron
microscopy (SEM) was applied to investigate the surface
characteristic and morphology of PA and GO/PA NC coated on
cellulose paper. The prepared MEPS device was used for extraction
of organophosphorous pesticides (OPPs) including chlorpyrifos,
fenthion, fenithrothion, ethion, edifenphos and phosalone in
environmental aqueous samples followed by detection using gas
chromatography-flame ionisation detector (GC-FID). Important
parameters affecting the MEPS method including pH of sample
solution, extraction draw-discard cycles, sorbent layers, desorption
solvent volume and desorption draw-eject number were studied
and optimised using central composite design (CCD). Based on the
method validation, limits of detection (LODs) were in the range of
0.2–1 μg L−1. The calibration graphs for chlorpyrifos, fenthion and
edifenphos are linear in the concentration range of 1 to 500 μg
L−1; for ethion and phosalone are linear in the range of 1–1000 μg
L−1 and for fenithrothion is linear in the range of 3–1000 μg L−1.
The method precision (RSD %) with six replicates determinations
was in the range of 3 to 9.4 % and 3.9 to 11.9% for distilled water
and spiked river water sample, respectively, at the concentration
level of 300 μg L−1 . The developed method was applied successfully
to determine OPP compounds in river, dam and tap water
samples; accordingly, the relative recoveries (RR%) were obtained
in the range of 77.8 to 113.3%.
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