Calculation of non-linearities of the calibration curves in atomic absorption flame spectroscopy

The deviations from the linear relationship between absorbance and concentration in atomic absorption measurements are calculated. Besides the chemical reactions there are four groups of interferences: (a) profiles of emission- and absorption lines (b) hyperfine structure (c) optics around the flame (d) non resonant light detected by the amplifier due to the optical arrangement and/or resolution of the monochromator.

The calculations show that curvature of experimental curves as obtained by apparatus for atomic absorption spectroscopy is caused partly by optical compromises and partly by the emission profile of the source. With a narrow simple emission line profile of the source and a precision monochromator a linear relationship within a few percent is possible up to 95 per cent absorption in a flame at atmospheric pressure.