Uncertainty of atomic absorption spectrometry: Application to the determination of lead in blood

The major sources of uncertainty of a method for determination of Pb in whole blood by atomic absorption spectrometry were identified. The combined uncertainty was compared to the experimentally determined variation and a satisfactory agreement was found, indicating that no significant sources of uncertainty have been overlooked and that the method is in a state of statistical control. The findings suggest that the major source of uncertainty at low concentrations are random fluctuations (noise) of the atomic signal. Therefore, if improvement of the method performance is needed, only actions directed towards enhancing the signal-to-noise ratio are suitable.