Define the Beer's Law - Nutritional  Biochemistry?

Beer's law states that the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of the transmitted light.

Mathematically, Beer's law is expressed as

A = abc

Where,

A = Absorbance

a = Proportionality constant defined as absorptivity

b = Light path in centimeters

c = Concentration of the absorbing compound, usually expressed in grams per liter

This equation forms the basis of quantitative analysis by absorption photometry.

Absorbance values have no units; hence, the units for a are the reciprocal of those for b and c. When b is 1 cm and c is expressed in moles per liter, the symbol ∈ (epsilon) is substituted for the constant a. The value for  ∈ is a constant for a given compound at a given wavelength under prescribed conditions of solvent, temperature, pH, etc., and is called the molar absorptivity. Values for ∈ are useful to characterize compounds, establish their purity, and compare sensitivities of measurements obtained on derivatives.