Dispersive liquid-liquid microextraction procedure 
based on ionic liquid
In a typical experiment, 5.0 mL of aqueous solution 
containing 50 µg/L Pd(II) in a 10-mL test tube with 
conical bottom, 1 mL phosphate buffer (0.01 mol/L, 
pH 3) and 0.5 mL of 10
-4
mol/L PAN solution were 
mixed. Then, by using a 5-mL syringe, 1 mL 
ethanol containing 100 μL [Hmim][PF6] was added to 
the above mentioned solution. The mixture was centrifuged
for 5 min at 3000 rpm. The volume of the 
sedimented phase was determined by use of a 100-μL 
Hamilton syringe. The sedimented phase (ionic liquid) 
was transferred to another test tube and allowed 
to evaporate at room temperature. Finally, the residue 
was dissolved into 0.5 mL ethanol and the Pd(II) 
ion concentration was determined by flame atomic 
absorption spectrometry. Pd(II) standard solutions 
(0.2-2.2 µg/mL), obtained by the serial dilutions 
of the stock solution with double distilled water, 
were prepared daily and their absorbances were read along
with the samples.