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Abstract
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In the present work, a new magnetic solid phase extraction method performed in a narrow-bore tube
using synthesized Fe3O4@SiO2@C8 magnetic nanoparticles has been developed. The method was
designed to extract and preconcentrate trace amounts of some pesticides in fruit and vegetable
samples. To obtain low limits of detection, a dispersive liquid–liquid microextraction method was performed
after magnetic solid phase extraction. In the practical procedure, small amounts of the sorbent
were added and moved down through the aqueous solution of the analytes placed in the tube under
force of gravity instead of passing the solution from a cartridge, as performed in traditional solid phase
extraction. Subsequently, the sorbent which collected at the bottom of the tube was transferred to the
top of the solution using an external magnet and was released to move down through the solution. This
step was repeated four times in order to increase the extraction efficiency. Then, the adsorbed analytes
were desorbed using methanol. The extract was subjected to dispersive liquid–liquid microextraction.
Under the optimum extraction conditions, the method showed wide linear ranges with low limits of
detection (0.03 to 0.17 mg kg1
). Enrichment factors and extraction recoveries were in the ranges of
2133 to 2733 and 64% to 82%, respectively. The relative standard deviations for 5, 20, and 100 mg L1 of
each analyte were equal to or less than 8% for intra-day (n = 6) and inter-day (n = 4) precisions.
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