Therefore, due to the interferences present,
the lead content of the samples has to be measured
by the standard addition method. The precision
of the method calculated as coefficient of
variation (ten replicate determinations, mean
concentration of 60 rig/ml) was 5.9%.
For the instrumental conditions used in the
analysis of the samples, the analytical detection
limits calculated, defined as the concentration of
Pb corresponding to three times the standard