The effect of sample volume on the extraction efficiency was
also examined by using model solutions prepared in the range of
10–40 mL and keeping other conditions constant. When the
volume of sample was greater than 15 mL, the recovery of Cu(II)
ions was not quantitative.Therefore,15 mL was selected as the
greatest working sample volume.The calculated preconcentration
factor was 60 when the final volume was 0.25 mL.