| In present study, a new sample pretreatment method based on the
combination of stirring-assisted ferrofluid-based liquid phase
microextraction and dispersive liquid–liquid microextraction has
been developed for the extraction of some pesticides (diazinon,
deltamethrin, fenpropathrin, phosalone, prometryn, simazine, and
terbutryn) from herbal distillate samples. In this method, a few
microlitre of a synthesised ferrofluid as an extraction solvent is
added into the sample solution containing the analytes and the
mixture is stirred at a high rate to increase the contact area between
the ferrofluid and sample solution. Then the stirring procedure is
stopped and the ferrofluid droplets containing the analytes are
collected on the surface of stir bar. In the next step, the stir bar is
washed with acetonitrile. In the following, the obtained mixture of
acetonitrile and ferrofluid is rapidly injected into deionised water.
The ferrofluid droplets are settled down at the bottom of a conical
test tube and after back-extraction of the analytes into n-hexane, an
aliquot of the extractant phase is injected into gas chromatography–
mass spectrometry. Under optimum conditions, the introduced
method offered high enrichment factors (1643−1884) and
extraction recoveries (82–94%), low limits of detection (3.1–7.3 ng
L–1) and quantification (10.3–24.3 ng L–1), and an acceptable repeatability
(relative standard deviation ≤ 7.9%). |