I'm currently doing a project that involves beer-lambert's law and am confused as to what it actually calculates. So far, my intuition goes as follows: The molar extinction coefficient is for the solvent at a specific concentration and wavelength. In this case, it is blood. And if you have to calculate the concentration of a solute, then you have to get a wavelength that is primarily absorbed by the solute. So the question is: if I have another wavelength that primarily absorbs something in the blood, then will the molar extinction coefficient be that of blood at that wavelength?