Previous experiments were performed with one extraction cycle.
To study the number of extraction cycles, 65–212 lm particle
size of pomegranate peels extracted with water at 40 C and
102.1 atm for 5 min. The extraction cell was then rinsed with fresh
water (5%) and purged with nitrogen gas flow for 100 s. Each extract
of five cycles was separately collected in five different collection
bottles. Each extract was transferred to a 250 ml volumetric
flask and the total volume was adjusted to 250 ml with water.
81.7% of TPC in total five cycles were extracted in the first cycle
(Fig 2). Two, three, and four extraction cycles were enough to extract
more than 90%, 95%, and 99% of the phenolics, respectively.
Theoretically infinite number of extraction cycles must be applied
to obtain 100% of the analytes in the sample matrix. Convenient
number of extraction cycle should be selected according to the
purpose. We selected two extraction cycles for subsequent experiments
for meaningful comparison of the present PWE method
with existing methods.