Triton X-114 solution was added into a 15 mL
calibrated centrifuge tube, and the mixture was buffered
to pH 5.0 with acetic-acetate, and then diluted to 15 mL
with double distilled water. The resultant solution
was kept in a thermostatic water bath at 50 oC for 15 min,
separation of the aqueous and surfactant-rich phase
was accomplished by centrifugation for 5 min at 3500 rpm.
After cooling in an ice bath, the surfactant-rich phase
becomes viscous and the supernatant aqueous phase
was then separated completely by a syringe centered in the tube.
To decrease the viscosity of the surfactant-rich phase,
the surfactant-rich phase was diluted to 0.5 mL by nitric acid
in methanol(0.1 mol L-1) solution, and then the resultant
solution was directly introduced into FAAS for
determination of copper.