a two-level full factorial design was performed
with the following variables: aluminium modifier mass, pyrolysis
time, pyrolysis temperature and atomization temperature. In the
step second, a Box–Behnken design was also used to determine
the critical conditions for these factors
The two-level full factorial design (24) was established, with
four additional experiments at the central point. The experimental
variables as coded and real values for the four factors and several
chemometric responses are shown in Table 2.