2.3.3. Solvent and centrifuge temperature
The grapefruit juice (3 mL) was mixed with 3 mL solvent (MeOH,
ACN and DMSO) and vortexed for 5 s and centrifuged at 6720×g
and extracted separately by maintaining the rotor temperature at
0, 10 and 20
◦
C for 10 min.
These centrifuge temperatures were selected for explaining any
possible trends in the top and bottom 1 mL of extracts. Since EtOH
and DMF showed similar extraction patterns as MeOH and DMSO,
they were not used in this experiment. The samples were prepared
by filtering 1 mL from the top and bottom of the centrifuge tube
without disturbing the extracts. The samples were later analyzed
in HPLC.
2.3.4. Extraction cycles
Grapefruit juice (3 mL) was extracted with 3 mL of DMSO in
a centrifuge tube. The sample mixture was vortexed for 5 s, centrifuged at 6720×gfor 10 min and the supernatant was analyzed
in HPLC. The residue was extracted two times with 3 mL DMSO,
filtered through 0.45m acrodisc filter and analyzed separately