A spectrophotometer is an instrument that measures the amount of light absorbed by a sample. Spectrophotometer techniques are mostly used to measure the concentration of solutes in solution by measuring the amount of the light that is absorbed by the solution in a cuvette placed in the spectrophotometer. Scientist Arnold J. Beckman and his colleagues at the National Technologies Laboratory (NTL) invented the Beckman DU spectrophotometer in 1940.

The spectrophotometer technique is to measure light intensity as a function of wavelength. It does this by diffracting the light beam into a spectrum of wavelengths, detecting the intensities with a charge-coupled device, and displaying the results as a graph on the detector and then on the display device.

  1. In the spectrophotometer, a prism (or) grating is used to split the incident beam into different wavelengths.
  2. By suitable mechanisms, waves of specific wavelengths can be manipulated to fall on the test solution. The range of the wavelengths of the incident light can be as low as 1 to 2nm.
  3. The spectrophotometer is useful for measuring the absorption spectrum of a compound, that is, the absorption of light by a solution at each wavelength.

Some of the major applications of spectrophotometers include the following:

  • Detection of concentration of substances
  • Detection of impurities
  • Structure elucidation of organic compounds
  • Monitoring dissolved oxygen content in freshwater and marine ecosystems
  • Characterization of proteins
  • Detection of functional groups
  • Respiratory gas analysis in hospitals
  • Molecular weight determination of compounds
  • The visible and UV spectrophotometer may be used to identify classes of compounds in both the pure state and in biological preparations.

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