# Lambert Beer's law deviations

Can somebody explain as concrete as possible, how the change of temperature and the change of pH leads to deviations of this law?

• I don't understand what you mean. Lambert Beer law apply for fixed temperature and pH. – user1420303 Mar 18 '15 at 15:41

A compound S follows the Lambert-Beer law if the absorbance $E_\lambda$ at a particular wavelength $\lambda$ is proportional to the concentration $c$ of S.
$E_\lambda = \left(\frac{I_0}{I} \right) = \epsilon\cdot c \cdot d$
A "deviation" is observed when the real concentration $c$ is different from the expected/assumed.
• variation of the pH leads to (de)protonation and forms another species with a completely different absorption spectrum, or at least a different $\epsilon$ at the wavelength under observation