are diluted in the same manner, the salicylate concentrations in
the unknown solutions can be extracted directly from the calibration
curve without any dilution calculations. This method is
valid for concentration determination, but the plot will underestimate
the extinction coefficient for the iron–salicylate complex
by approximately two orders of magnitude. The experiment
may be modified to require a plot of absorbance versus actual
salicylate concentration (after dilution in the reaction mixture)
to properly determine the extinction coefficient.