In DLLME, extraction time is defined as interval time between
injection the mixture of disperser (acetone) and extraction solvent
(octanol) into the aqueous sample and starting to centrifuge.
It is noted that after formation of the cloudy solution, the
contact area between extraction solvent and aqueous phase
(sample) is infinitely large. Thereby, transition of the analytes
from aqueous phase (sample) to the extraction solvent is very
fast. Subsequently, the equilibrium state is achieved quickly so
the extraction time is very short. This is an advantage of the
DLLME technique, i.e., low extraction time. In this method,
the time-consuming step is the centrifuging of sample solution
in extraction procedure. The effect of extraction time was
examined in the range of 1–25 min while the other experimental
conditions remained constant. The obtained results are shown in Fig 6. As a result, 5 min was selected for further
studies.