3.8. Analytical performance
Under the optimized conditions, calibration curves were constructed
for the determination of cadmium and copper ions,
according to the general procedure. Linearity was maintained 1–100 ng mL−1 for cadmium and 1–150 ng mL−1 for copper in initial
solution. The correlation of determination (r2) was 0.998 for cadmium
and 0.997 for copper ions. The limits of detection, defined
as CLOD = 3Sb/m, where Sb is the standard deviation of 10 replicate
blank signals and m is the slope of the calibration curve after preconcentration,
for a sample volume of 500 mL, were found to be
0.15 and 0.45 ng mL−1 for cadmium and copper ions, respectively. The relative standard deviation for 10 separate column experiments
for the determination of 5.0 g cadmium and copper ions
in 100 mL water was 3.4 and 3.8%, respectively. The corresponding
limit of detection (LOD), regression equation, dynamic linear range
(DLR), correlation of determination (r2), preconcentration factor
(PF), recovery, and maximum sorption capacity were calculated
under optimized conditions and summarized in Table 4.