Under the optimized conditions, calibration curves were
sketched for the determination of cadmium and lead ions
according to the general procedure. Linearity was maintained
0.5–110 lg L1 for cadmium and 2–300 lg L1 for lead in initial
solution. The coefficient of determination (r
2
) was 0.995 for cadmium
and 0.997 for lead ions. The limit of quantification was 0.5
for cadmium and 2 lg L1 for lead ions, respectively. The limit of
detection which is defined as CLOD = 3Sb/m, where Sb is the
standard deviation of ten replicate blank signals, and m is the slope
of the calibration curve after preconcentration, for a sample volume
of 50 mL, was found to be 0.2 lg L1 for cadmium and 1.2 lg L1 for
lead ions, respectively. Also, the preconcentration factors calculated
as the ratio between the slopes of the calibration curves acquired by
the proposed method (Y = 16.76X + 0.001 (cadmium ions) and
Y = 3.84X + 0.019 (lead ions)) and through the direct analysis of cadmium
and lead ions by FAAS (Y = 0.056X 0.002 (cadmium ions)
and Y = 0.028X 0.022 (lead ions)), were found to be 299.3
(16.76/0.056 = 299.3) and 137.1 (3.84/0.028 = 137.1) for cadmium
and lead ions, respectively. The relative standard deviations for
eight separate extraction experiments for determination of
50 lg L1 of cadmium and lead ions was 2.8% and 2.2%, respectively.
Table 2 shows a comparison between the proposed method
and other previously reported methods.
3.10.