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I have completed a whole set of FITR-ATR spectra analysing 6 solutions of ethanol-water mixtures, all at different concentrations of each.

I have now been instructed to use the method of differential absorption to determine the concentration of ethanol. I am subtracting the absorbance at the base of the C-H stretch of ethanol from the maximum absorbance of the same stretch so now I have a difference in absorbance value. At this stage, I am a little confused as to how I use this value to obtain the concentration of ethanol. All I know is that the Beer-Lambert law is involved somehow.

Any help with this would be appreciated. Thanks.

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    $\begingroup$ The absorbance is proportional to the concentration of ethanol. $\endgroup$ – Maurice Oct 10 '20 at 19:13
  • $\begingroup$ See Beer–Lambert law $\endgroup$ – MaxW Oct 10 '20 at 19:57
  • $\begingroup$ @Dave, Can you add more details? Are you correcting the baseline? $\endgroup$ – M. Farooq Oct 11 '20 at 1:55
  • $\begingroup$ A starter: researchgate.net/post/… $\endgroup$ – Buttonwood Oct 11 '20 at 17:28