The static valve was closed and the pump kept on pumping until
the pressure of the extraction cell reached 102.1 atm. The cell
was preheated at 40 C for 5 min, followed by a 5 min static extraction
step. After 5 min static extraction, the extracts were pumped
into 250 ml of collection vials. Fresh solvent (60% of the cell volume)
was pumped again into the cell and nitrogen gas purged
for 100 s. The extracts collected in vials were transferred into a
250 ml of volumetric flasks and the total volume was adjusted to
250 ml with water. One extraction cycle was applied for the determination
of the effective extraction factors. Particle size, temperature,
static time, and flush volume were investigated as
independent factors. Effects of independent factors on system responses
were determined by changing the level of each factor
and keeping the other factors constant. After determination of
the optimum levels of independent factors, the number of optimum
extraction cycles was determined at optimum extraction
conditions.