Uncertainty of atomic absorption spectrometer

The uncertainty of the flame atomic absorption spectrometer was studied. Drift of signal, noise, and nonlinearity of the calibration curve were found to be main sources of uncertainty for the absorbance measurement, and factors affecting these sources of uncertainty were evaluated using Cd as a typical element. The combined uncertainty was 0.00133 absorbance units at a Cd concentration of 0.5 mg/l (0.078 absorbance units). The relationship between the flame conditions and the burner optics contributed strongly to the uncertainty. Therefore, the matrix effect of the sample must to be taken into consideration in actual analyses.