One of the most important parameters that can
influence extraction efficiency and selectivity in
USE is the solvent nature, which is a critical parameter
in multiresidue analysis. Since the target
list of pesticides included highly a-polar and midpolar
compounds and even degradation products
the extraction solvent should have polarity properties
compatible with all analytes.
In the optimization of ultrasonic extraction
different solvents with a broad range of polarity
were used for sonication. The ultrasonic extraction
efficiency of the solvents was checked by
calculating of recoveries. Table 2 summarizes recovery
results of the 17 OCPs obtained with nhexane,
acetone, dichloromethane, methanol, and
ethyl acetate.
Methanol, though known as a traditional polar
solvent, showed the lowest recovery efficiencies
of all the solvents studied. In general the recovery
values obtained with this solvent were
unacceptable for many of the target compounds,
ranging from 30.32 to 92.33%. It was also evident
that n-hexane which is a non polar solvent,