3.5. Analytical features
The analytical features of merit of the proposed method were
established by using aqueous standards (4% HF, 6% PTFE) and the furnace program shown in Table 2. The calibration curves were
established with a blank and five calibration solutions in the
concentration range of 2.5–50 μg/L. In order to compare the slopes of
the calibration and standard addition graphs for slurries of NIST 2709
the t-test was applied. No significant differences at a confidence level of
95% between the slopes of the additions and calibration graphs for the
antimony were found, which suggests that both calibrations were
statistically similar. The absence of significant matrix effects affords
direct calibration with aqueous standards when using blank sample.
The detection limit (LOD, calculated as the average of 5 blank
samples' signals plus three times the standard deviation of the signals
obtained from 5 blank samples) and the quantification limit (LOQ,
calculated as the average of 5 blank samples' signals plus ten times the
standard deviation of the signals obtained from 5 blank samples) for a
5% slurry sample were 0.04 and 0.13 μg/g, respectively. The
characteristic mass, based on integrated absorbances (amounts, in
picograms, providing a signal of 0.0044 s), was 10.6.