A Colormetric Study Of Alizarin Red S

Spectrophotometry refers to the relative measurement of radiant energy or radiant flux as a function of wavelength. It applies not only to visual measurements, but also to photographic and photoelectric methods of measurement in the ultraviolet, infrared, and visible regions of the spectrum. The word relative is important in this descriptive definition of spectrophotometry because the measurements are always made relative to some standard. All spectrophotometers have the following essential features in common: a light source, a system for dispersing the light, a cell containing the sample and a cell containing the standard, and a device for comparing the intensity of the light transmitted by the sample and the intensity of the light transmitted by the standard. The method of comparing these intensities is the basis of a three-fold classification of spectrophotometers: visual, photoelectric, and photographic. Since only the photoelectric spectrophotometer was used in gathering the experimental data for this paper, it alone will be discussed