Beer-Bouguer Law (Beer-Lambert Law)

n Combined laws expression absorption of radiant energy of a single wavelength as a function of concentration and optical path length of absorbing material:

$$ - {\rm Log\ Ti/cl = K}$$

where T_i is the internal transmittance, c is the concentration, l is the path length, and K is the unit absorption coefficient. The value −Log T_i is sometimes called the optical density, OD, or simply the density, d; it is sometimes called the absorption, the absorbency, or the extinction. The unit absorption coefficient, K, is sometimes designated A, a, α, E, or є. The units of concentration and path length must be specified. See Absorption Coefficient. Note − In Europe, it is called the Law of Lambert-Beer. (DeLevie R (1996) Principles of quantitative analysis. Mc-Graw-Hill Higher Education, New York; Willard HH, Merritt LL, Dean JA (1974) Instrumental methods of analysis, D Van Nostrand, Company, New York).