A 5 mL of a standard solution or real sample was placed
into an extraction vessel. Acetone (2.00 mL) as a disperser
containing 300 lL octanol (as an extraction solvent) was
rapidly injected into the solution using a syringe. A cloudy
solution (water/acetone/octanol) was formed in the extraction
vessel. In this step, the RB in water sample was extracted
into the fine droplets of octanol. The mixture was
then centrifuged for 5 min at 4000 rpm. After this process,
the dispersed fine droplets of octanol were collected and
were dissolved in methanol and were transported to a
UV–Vis spectrophotometer to measure its absorbance at
kmax (530 nm).