Situations where Beer-Lambert Law may not hold include:
Chemical Deviations:
Association/Dissociation: At high concentrations, molecules may associate or dissociate, altering the absorbing species.
Reactions with Solvent: Chemical interactions between solute and solvent can change the nature of the absorber.
Instrumental Deviations:
Stray Light: Light outside the selected bandwidth can cause overestimated absorbance.
Polychromatic Radiation: Non-monochromatic light may lead to errors, especially for samples with sharp absorption peaks.
Physical Deviations from Beer-Lambert Law:
High Concentrations: Changes in refractive index can affect absorption at very high solute concentrations.
Temperature/Solvent Effects: Variations in solvent or temperature can alter peak shape and position.
Light Scattering: Particles or droplets scatter light, distorting absorbance readings.