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Specific absorption coefficient

Definition

noun

A factor that measures the absorbance of light per unit of path length (of the spectrophotometer cuvette, usually expressed in centimeter) and per unit of mass concentration (usually expressed in grams/liter)


Supplement

Specific absorption coefficient is used in absorbance measurements. One of its applications in biology is for estimating the concentration, for example, of the chlorophyll pigment when the absorbance of the pigment sample is determined through a spectrophotometer1, and using the formula2,:

Concentration of Pigment (mg/L) = [Absorbance units/Specific Absorption Coefficient (L g-1 cm-1)] *1000

The concentration of the pigment in a sample can be estimated when the specific absorption coefficient is known. To obtain the specific absorption coefficient, the pigment is first purified from contaminants and then dissolved in a specific solvent. After the pigment is purified, its absorbance is measured using a spectrophotometer. This value would then serve as the universal standard when quantifying pigment concentrations from absorbance measurements. 2


Compare:

Reference(s):
1Stewart, W. D. P.. "Chlorophylls: Analysis." Algal physiology and biochemistry. Berkeley: University of California Press, 1974. 165-166. Print.
2"Absorbance Theory & Application."Turnerdesigns.com. N.p., n.d. Web. 28 Feb. 2014. Turnerdesigns.com/t2/doc/appnotes/S-0075.pdf.


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