The sample mass was transmitted to the instrument's computer to calculate the integrated absorbance normalised to a sample
mass of 1.0 mg after each measurement. The aqueous standards were
injected manually onto the platform using a micropipette. Argon with
a purity of 99.996% (White Martins, São Paulo, Brazil) has used as a
purge gas with a flow rate of 2.0 L min − 1 during all stages, except during
atomisation, when the flow was stopped for the determination of Pb
and Cr, respectively. The optimum parameters for the graphite furnace
temperature for both elements are shown in Table 1.