analysis by emission would also be expected to exhibit a linear relationship between concentration and observed intensity . however, for the reasons listed above plus self-absorption, the relationship between concentration and intensity is also nonlinear in many cases. figure 7.2 shows the relationship between concentration and intensity for sodium.
in the pass , it was necessary to plus an absorbance vs. concentration curve for several standards to get an accurate reading of elemental content when samples were out of the linear range. one could also dilute the samples to be analyzed so that they would fall in the linear range.