Use of methanol as the extraction reagent in MAE could
provide a higher percent recovery than acetonitrile. It might be
due to polar compounds being more soluble in methanol than
acetonitrile. Ten polar compounds among the 21 compounds
could not be extracted using acetonitrile alone or acetonitrile–
water (95:5). By using acetonitrile–water (7:3) or acetonitrile–
water (1:1), low recovery was observed, for example from 10 to
60 % for the ten compounds. The use of methanol as the
extraction reagent the better recovery was obtained. The effect
of methanol–water composition on recovery of the compounds
was demonstrated for MAE at 60 °C. Using methanol–water
(95:5) the recovery of 64–110 % was achieved for the 21
compounds. It is clear that the addition of a small amount of
water enhances the extraction efficiency, but which for some
compounds decreased when water content was higher. As the
water content increases, the dielectric constant of mixture