3.9. Effect of CCl4 volume
The volume of extraction solvent is another crucial parameter that
could affect the extraction efficiency, enrichment factor, and sensitivity,
due to its effect on the volume of the sedimented phase. In
order to examine the effect of this parameter, different volumes of
CCl4 (180–500 mL) containing Aliquat 336 (0.67% w/v) were subjected
to the same DLLME procedure. The obtained results in Fig. 6 show
that the absorbance of organic phase is decreased by increasing the
volume. Due to the dilution effect which decreases the concentration
of the extracted colored product in the sedimented phase. Thus, in
order to achieve high enrichment factor and low detection limit,
180 mL of CCl4 containing 0.67% (w/v) of Aliquat 336 was selected as
the optimum volume. Using injection volumes less than 180 mL of the
solution, low volume of organic phase was obtained, so that the
absorption signal could not be measured by spectrophotometer even
fitted with micro-cells