Search results
Results From The WOW.Com Content Network
The extinction law's primary application is in chemical analysis, where it underlies the Beer–Lambert law, commonly called Beer's law. Beer's law states that a beam of visible light passing through a chemical solution of fixed geometry experiences absorption proportional to the solute concentration .
The absorbance of a material that has only one absorbing species also depends on the pathlength and the concentration of the species, according to the Beer–Lambert law =, where ε is the molar absorption coefficient of that material; c is the molar concentration of those species; ℓ is the path length.
Variable pathlength absorption spectroscopy uses a determined slope to calculate concentration. As stated above this is a product of the molar absorptivity and the concentration. Since the actual absorbance value is taken at many data points at equal intervals, background subtraction is generally unnecessary.
To normalize the concentration to a 10mm equivalent, the following is done: 0.6 OD X (10/3) * 50 μg/mL=100 μg/mL Most spectrophotometers allow selection of the nucleic acid type and path length such that resultant concentration is normalized to the 10 mm path length which is based on the principles of Beer's law.
An absorption spectrum can be quantitatively related to the amount of material present using the Beer–Lambert law. Determining the absolute concentration of a compound requires knowledge of the compound's absorption coefficient. The absorption coefficient for some compounds is available from reference sources, and it can also be determined by ...
The amount of light transmitted through a material diminishes exponentially as it travels through the material, according to the Beer–Lambert law (A = (ε)(l)). Since the absorbance of a sample is measured as a logarithm, it is directly proportional to the thickness of the sample and to the concentration of the absorbing material in the sample.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Both Beer's Law and Planck's Law can be derived from Schwarzschild's equation. [14] In a sense, they are corollaries of Schwarzschild's equation. When the spectral intensity of radiation is not changing as it passes through a medium, dI λ = 0. In that situation, Schwarzschild's equation simplifies to Planck's law: