The main parameters that affect CPE and signal measurements
were evaluated by using an iron(III) reference solution (Fig. 2) and
the evaluated intervals and selected values are shown in Table 2Triton X-114 concentration is a critical parameter because both
blank and analytical signals increased with the surfactant amount
Fig. 2a). While low Triton X-114 concentrations hindered the
extraction efficiency, high amounts caused dilution of the SRP and
increased the blank values due to light scattering. The analytical
response was not significantly different from 1.5 to 3.0% Triton
X-114 and the lowest value was selected to minimize the blank
values and waste generation. The optimized concentration is 26fold
higher than the critical micelle concentration (0.35 mmolL−1)[22], then assuring the surfactant excess required for CPE. In the
proposed procedure, the surfactant was added to the reagent solution
to avoid the additional sample treatment required in previous
works [4,5,7].