· Measures the color concentration of a substance in a solution by deteecting the color light intensity passing through a sample containing the substance and a reagent
· Optical color filters are used to detect the color wavelength of interest. E.g., urine passes yellow light and absorbs blue and green
· Laser LEDs are preferred if their wavelength is suitable due to purity of the monochromatic color.
T= I1/I0 * 100%
A= - log I1/ I0
If the path length or concentration increases, the transmittance decreas es and absorbance increases, a phenomenon expres sed by Beer’s Law.
Absorbtivity related to the nature of the A=aCL absorbing substance and optical wavelength (known for a standar d solutionconcentration).
L: Cuvette path length