3.4. Validation of the methods
The results obtained for cadmium in the CRM using the standard
calibration technique with aqueous standard solutions are
summarized in Table 3. There is no statistic difference between
the results obtained by SS-ET AAS and SlS-ET AAS and the certified
value for the wheat flour CRM, and between the results obtained by
SS-ET AAS and the certified value for the other CRM on a 95% con-
fidence level, based on a Student t-test. This result demonstrates
that cadmium in wheat flour samples can be directly determined
using the standard calibration technique. The other CRM have not been investigated using SlS-ET AAS because of their significantly
different physical structure, which would have necessitated further
optimization of the slurry preparation procedure. SS-ET AAS,
in contrast, is not affected by these differences in the physical structure
and can therefore be considered the more rugged technique.